AUTHOR COMMENT 1

3 1 Also, the first line in the Table 3 key says SC is the critical saturation (sc = SC + 1) in STN 2 and is comparable to SCk (=sck -1) in HYB.It should say SC is the critical supersaturation 3 (sc =SC +1) in STN and is comparable to SCk (=sck -1) in HYB. 4 Thank you for your correction. Yes, you are right. We will correct it in the revised 5

manuscript.

AUTHOR COMMENT 1

3 1 Also, the first line in the Table 3 key says SC is the critical saturation (sc = SC + 1) in STN 2 and is comparable to SCk (=sck -1) in HYB.It should say SC is the critical supersaturation 3 (sc =SC +1) in STN and is comparable to SCk (=sck -1) in HYB. 4 Thank you for your correction. Yes, you are right. We will correct it in the revised 5

manuscript.

INTERACTIVE COMMENT ON “OZONOLYSIS OF Α-PINENE: BY R. K ACPD 7, S1601–S1604, 2007 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper EGU Atmos. Chem. Phys. Discuss., 7, S1601–S1604, 2007

AUTHOR COMMENT 1

3 1 Also, the first line in the Table 3 key says SC is the critical saturation (sc = SC + 1) in STN 2 and is comparable to SCk (=sck -1) in HYB.It should say SC is the critical supersaturation 3 (sc =SC +1) in STN and is comparable to SCk (=sck -1) in HYB. 4 Thank you for your correction. Yes, you are right. We will correct it in the revised 5

manuscript.

AUTHOR COMMENT 1

3 1 Also, the first line in the Table 3 key says SC is the critical saturation (sc = SC + 1) in STN 2 and is comparable to SCk (=sck -1) in HYB.It should say SC is the critical supersaturation 3 (sc =SC +1) in STN and is comparable to SCk (=sck -1) in HYB. 4 Thank you for your correction. Yes, you are right. We will correct it in the revised 5

manuscript.

AUTHOR COMMENT 1

3 1 Also, the first line in the Table 3 key says SC is the critical saturation (sc = SC + 1) in STN 2 and is comparable to SCk (=sck -1) in HYB.It should say SC is the critical supersaturation 3 (sc =SC +1) in STN and is comparable to SCk (=sck -1) in HYB. 4 Thank you for your correction. Yes, you are right. We will correct it in the revised 5

manuscript.

INTERACTIVE COMMENT ON “OZONOLYSIS OF Α-PINENE: BY R. K ACPD 7, S1601–S1604, 2007 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper EGU Atmos. Chem. Phys. Discuss., 7, S1601–S1604, 2007

AUTHOR COMMENT 1

3 1 Also, the first line in the Table 3 key says SC is the critical saturation (sc = SC + 1) in STN 2 and is comparable to SCk (=sck -1) in HYB.It should say SC is the critical supersaturation 3 (sc =SC +1) in STN and is comparable to SCk (=sck -1) in HYB. 4 Thank you for your correction. Yes, you are right. We will correct it in the revised 5

manuscript.

ATMOSPHERIC INTERACTIVE COMMENT ON “TEMPERATURE ANDAND PHYSICS ACPD 11, C1065–C1067, 2011 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Page 3675 3 line 3.0 g l-1 should be 3.0 ng l-1 ACPD - AVERAGE MOLECULAR WEIGHT OF SURFACTANTS IN AEROSOLS9 Abstract. Surfactants in atmospheric aerosols determined as methylene blue active substances (MBAS) and ethyl violet active substances (EVAS). The MBAS and EVAS concentrations can THE RATIO OF NO2/NOX DIRECTLY EMITTED FROM VEHICLES ACPD 5, 12723–12740, 2005 The ratio of NO2/NOx directly emitted from vehicles X. Yao et al. Title Page Abstract Introduction Conclusions References Tables Figures ATMOSPHERIC INTERACTIVE CHEMISTRY INTERACTIVE COMMENT ON ACPD 11, C15005–C15007, 2012 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Atmos. Chem. Phys. Discuss., 11, C15005–C15007, 2012 ATMOSPHERIC INTERACTIVE COMMENT ON “OZONE PRODUCTION IN ACPD 10, C9465–C9470, 2010 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Atmos. Chem. Phys. Discuss., 10, C9465–C9470, 2010 ATMOSPHERIC INTERACTIVE COMMENT ON “SIMULATION OF PARTICLE ACPD 11, C7984–C7998, 2011 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Page 14661, line 25: Change “is the major publically” to “is a

publically”.

ATMOSPHERIC INTERACTIVE COMMENT ON “TEMPERATURE ANDAND PHYSICS ACPD 11, C1065–C1067, 2011 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Page 3675 3 line 3.0 g l-1 should be 3.0 ng l-1 ACPD - AVERAGE MOLECULAR WEIGHT OF SURFACTANTS IN AEROSOLS9 Abstract. Surfactants in atmospheric aerosols determined as methylene blue active substances (MBAS) and ethyl violet active substances (EVAS). The MBAS and EVAS concentrations can THE RATIO OF NO2/NOX DIRECTLY EMITTED FROM VEHICLES ACPD 5, 12723–12740, 2005 The ratio of NO2/NOx directly emitted from vehicles X. Yao et al. Title Page Abstract Introduction Conclusions References Tables Figures ATMOSPHERIC INTERACTIVE CHEMISTRY INTERACTIVE COMMENT ON ACPD 11, C15005–C15007, 2012 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Atmos. Chem. Phys. Discuss., 11, C15005–C15007, 2012 ATMOSPHERIC INTERACTIVE COMMENT ON “OZONE PRODUCTION IN ACPD 10, C9465–C9470, 2010 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Atmos. Chem. Phys. Discuss., 10, C9465–C9470, 2010 ATMOSPHERIC INTERACTIVE COMMENT ON “SIMULATION OF PARTICLE ACPD 11, C7984–C7998, 2011 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Page 14661, line 25: Change “is the major publically” to “is a

publically”.

ATMOSPHERIC INTERACTIVE COMMENT ON “TEMPERATURE ANDAND PHYSICS ACPD 11, C1065–C1067, 2011 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Page 3675 3 line 3.0 g l-1 should be 3.0 ng l-1 ACPD - AVERAGE MOLECULAR WEIGHT OF SURFACTANTS IN AEROSOLS9 Abstract. Surfactants in atmospheric aerosols determined as methylene blue active substances (MBAS) and ethyl violet active substances (EVAS). The MBAS and EVAS concentrations can THE RATIO OF NO2/NOX DIRECTLY EMITTED FROM VEHICLES ACPD 5, 12723–12740, 2005 The ratio of NO2/NOx directly emitted from vehicles X. Yao et al. Title Page Abstract Introduction Conclusions References Tables Figures ATMOSPHERIC INTERACTIVE CHEMISTRY INTERACTIVE COMMENT ON ACPD 11, C15005–C15007, 2012 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Atmos. Chem. Phys. Discuss., 11, C15005–C15007, 2012 ATMOSPHERIC INTERACTIVE COMMENT ON “OZONE PRODUCTION IN ACPD 10, C9465–C9470, 2010 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Atmos. Chem. Phys. Discuss., 10, C9465–C9470, 2010 ATMOSPHERIC INTERACTIVE COMMENT ON “SIMULATION OF PARTICLE ACPD 11, C7984–C7998, 2011 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Page 14661, line 25: Change “is the major publically” to “is a

publically”.

ATMOSPHERIC INTERACTIVE COMMENT ON “TEMPERATURE ANDAND PHYSICS ACPD 11, C1065–C1067, 2011 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Page 3675 3 line 3.0 g l-1 should be 3.0 ng l-1 ACPD - AVERAGE MOLECULAR WEIGHT OF SURFACTANTS IN AEROSOLS9 Abstract. Surfactants in atmospheric aerosols determined as methylene blue active substances (MBAS) and ethyl violet active substances (EVAS). The MBAS and EVAS concentrations can THE RATIO OF NO2/NOX DIRECTLY EMITTED FROM VEHICLES ACPD 5, 12723–12740, 2005 The ratio of NO2/NOx directly emitted from vehicles X. Yao et al. Title Page Abstract Introduction Conclusions References Tables Figures ATMOSPHERIC INTERACTIVE CHEMISTRY INTERACTIVE COMMENT ON ACPD 11, C15005–C15007, 2012 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Atmos. Chem. Phys. Discuss., 11, C15005–C15007, 2012 ATMOSPHERIC INTERACTIVE COMMENT ON “OZONE PRODUCTION IN ACPD 10, C9465–C9470, 2010 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Atmos. Chem. Phys. Discuss., 10, C9465–C9470, 2010 ATMOSPHERIC INTERACTIVE COMMENT ON “SIMULATION OF PARTICLE ACPD 11, C7984–C7998, 2011 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Page 14661, line 25: Change “is the major publically” to “is a

publically”.

ACPD - AVERAGE MOLECULAR WEIGHT OF SURFACTANTS IN AEROSOLS Abstract. Surfactants in atmospheric aerosols determined as methylene blue active substances (MBAS) and ethyl violet active substances (EVAS). The MBAS and EVAS concentrations can “CHEMICAL COMPOSITION, MICROSTRUCTURE, AND HYGROSCOPIC ACPD 15, C4466–C4479, 2015 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Atmos. Chem. Phys. Discuss., 15, C4466–C4479, 2015 INTERACTIVE COMMENT ON “TEMPORAL AND SPATIAL SCALING ACPD 15, C241–C244, 2015 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Atmos. Chem. Phys. Discuss., 15, C241–C244, 2015 BY O. L. HADLEY ET AL. ACPD 10, C4206–C4208, 2010 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Atmos. Chem. Phys. Discuss., 10, C4206–C4208, 2010 “SCATTERING AND ABSORPTION PROPERTIES OF NEAR-SURFACE ACPD 14, C8995–C9006, 2014 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Atmos. Chem. Phys. Discuss., 14, C8995–C9006, 2014 AEROSOL-CLOUD INTERACTION DETERMINED BY BOTH IN SITU AND Aerosol-cloud interaction determined by both in situ and satellite data over a northern high-latitude site H. Lihavainen1, V.-M. Kerminen1 and L.A. Remer2 1Finnish Meteorological Institute, P.O. Box 503, FI-00101, Helsinki, Finland 2 NASA Goddard Space Flight Center, Greenbelt, MD, 20771, USA Abstract The first aerosol indirect effect over a clean, northern high-latitude site was investigated A CELL-FREE SOLUTION H. SHEN ET AL. PEROXIDE FROM SAN and not necessarily accurately represented by simple solutions. A: We believe that our quantitative approach is more useful than

correlations in de-

INTERACTIVE COMMENT ON “LOADING-DEPENDENT Α-PINENE SOA ACPD 8, S9761–S9769, 2008 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper experiments were conducted at higher mass loadings (700 µg m−3 to 30 µg m−3, see for example Figure 1 and Figure 3 in Grieshop et al.), and the general trend observed in

C3972

is put to third power and not GF. I'msorrybutinonlinediscussionversionofthismanuscriptthenumberfractionsnf1,2,3 are not put to third power, but the growth factors GF1 AUTHOR RESPONSE TO D. TARABORRELLI (REFEREE) Author Response to D. Taraborrelli (Referee) We thank Dr. Taraborrelli for taking the time to carefully review our manuscript and provide critical feedback and valuable insights. ACPD - AVERAGE MOLECULAR WEIGHT OF SURFACTANTS IN AEROSOLS9 Abstract. Surfactants in atmospheric aerosols determined as methylene blue active substances (MBAS) and ethyl violet active substances (EVAS). The MBAS and EVAS concentrations can ATMOSPHERIC CHEMISTRY INTERACTIVE COMMENT ON “PARTICULATE ACPD 9, C791–C793, 2009 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Atmos. Chem. Phys. Discuss., 9, C791–C793, 2009 THE RATIO OF NO2/NOX DIRECTLY EMITTED FROM VEHICLES ACPD 5, 12723–12740, 2005 The ratio of NO2/NOx directly emitted from vehicles X. Yao et al. Title Page Abstract Introduction Conclusions References Tables Figures ATMOSPHERIC INTERACTIVE COMMENT ON “TEMPERATURE ANDAND PHYSICS ACPD 11, C1065–C1067, 2011 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Page 3675 3 line 3.0 g l-1 should be 3.0 ng l-1 ATMOSPHERIC CHEMISTRY INTERACTIVE COMMENT ON ACPD 12, C5207–C5211, 2012 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Atmos. Chem. Phys. Discuss., 12, C5207–C5211, 2012 ACPD - AVERAGE MOLECULAR WEIGHT OF SURFACTANTS IN AEROSOLS9 Abstract. Surfactants in atmospheric aerosols determined as methylene blue active substances (MBAS) and ethyl violet active substances (EVAS). The MBAS and EVAS concentrations can ATMOSPHERIC CHEMISTRY INTERACTIVE COMMENT ON “PARTICULATE ACPD 9, C791–C793, 2009 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Atmos. Chem. Phys. Discuss., 9, C791–C793, 2009 THE RATIO OF NO2/NOX DIRECTLY EMITTED FROM VEHICLES ACPD 5, 12723–12740, 2005 The ratio of NO2/NOx directly emitted from vehicles X. Yao et al. Title Page Abstract Introduction Conclusions References Tables Figures ATMOSPHERIC INTERACTIVE COMMENT ON “TEMPERATURE ANDAND PHYSICS ACPD 11, C1065–C1067, 2011 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Page 3675 3 line 3.0 g l-1 should be 3.0 ng l-1 ATMOSPHERIC CHEMISTRY INTERACTIVE COMMENT ON ACPD 12, C5207–C5211, 2012 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Atmos. Chem. Phys. Discuss., 12, C5207–C5211, 2012 ATMOSPHERIC INTERACTIVE CHEMISTRY INTERACTIVE COMMENT ON ACPD 11, C11635–C11643, 2011 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Atmos. Chem. Phys. Discuss., 11, C11635–C11643, 2011 ACPD - AVERAGE MOLECULAR WEIGHT OF SURFACTANTS IN AEROSOLS9 Abstract. Surfactants in atmospheric aerosols determined as methylene blue active substances (MBAS) and ethyl violet active substances (EVAS). The MBAS and EVAS concentrations can THE RATIO OF NO2/NOX DIRECTLY EMITTED FROM VEHICLES ACPD 5, 12723–12740, 2005 The ratio of NO2/NOx directly emitted from vehicles X. Yao et al. Title Page Abstract Introduction Conclusions References Tables Figures ATMOSPHERIC INTERACTIVE COMMENT ON “TEMPERATURE ANDAND PHYSICS ACPD 11, C1065–C1067, 2011 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Page 3675 3 line 3.0 g l-1 should be 3.0 ng l-1 ATMOSPHERIC CHEMISTRY INTERACTIVE COMMENT ON ACPD 12, C5207–C5211, 2012 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Atmos. Chem. Phys. Discuss., 12, C5207–C5211, 2012 ATMOSPHERIC INTERACTIVE CHEMISTRY INTERACTIVE COMMENT ON ACPD 11, C11635–C11643, 2011 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Atmos. Chem. Phys. Discuss., 11, C11635–C11643, 2011 “NIGHTTIME OBSERVATION AND CHEMISTRY OF HO IN THE PEARL ACPD 13, C13094–C13102, 2014 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Atmos. Chem. Phys. Discuss., 13, C13094–C13102, 2014 INTERACTIVE COMMENT ON “ATMOSPHERIC BROWN CLOUDS REACH THE ACPD 14, C9811–C9812, 2014 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Atmos. Chem. Phys. Discuss., 14, C9811–C9812, 2014 AEROSOL-CLOUD INTERACTION DETERMINED BY BOTH IN SITU AND Aerosol-cloud interaction determined by both in situ and satellite data over a northern high-latitude site H. Lihavainen1, V.-M. Kerminen1 and L.A. Remer2 1Finnish Meteorological Institute, P.O. Box 503, FI-00101, Helsinki, Finland 2 NASA Goddard Space Flight Center, Greenbelt, MD, 20771, USA Abstract The first aerosol indirect effect over a clean, northern high-latitude site was investigated

AUTHOR COMMENT 1

3 1 Also, the first line in the Table 3 key says SC is the critical saturation (sc = SC + 1) in STN 2 and is comparable to SCk (=sck -1) in HYB.It should say SC is the critical supersaturation 3 (sc =SC +1) in STN and is comparable to SCk (=sck -1) in HYB. 4 Thank you for your correction. Yes, you are right. We will correct it in the revised 5

manuscript.

RESPONSE TO COMMENTS BY ANONYMOUS REFEREE #1 R#1-2 “PM2.5 element data (i.e. Silicon) used in this study was obtained from the Teflon filters through analysis using an energy dispersive X-ray fluorescence spectrometer (ED-XRF, Epsilin 5, ACPD - AVERAGE MOLECULAR WEIGHT OF SURFACTANTS IN AEROSOLS9 Abstract. Surfactants in atmospheric aerosols determined as methylene blue active substances (MBAS) and ethyl violet active substances (EVAS). The MBAS and EVAS concentrations can THE RATIO OF NO2/NOX DIRECTLY EMITTED FROM VEHICLES ACPD 5, 12723–12740, 2005 The ratio of NO2/NOx directly emitted from vehicles X. Yao et al. Title Page Abstract Introduction Conclusions References Tables Figures ATMOSPHERIC INTERACTIVE COMMENT ON “TEMPERATURE ANDAND PHYSICS ACPD 11, C1065–C1067, 2011 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Page 3675 3 line 3.0 g l-1 should be 3.0 ng l-1 ATMOSPHERIC CHEMISTRY INTERACTIVE COMMENT ON ACPD 12, C5207–C5211, 2012 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Atmos. Chem. Phys. Discuss., 12, C5207–C5211, 2012 ATMOSPHERIC INTERACTIVE CHEMISTRY INTERACTIVE COMMENT ON ACPD 11, C11635–C11643, 2011 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Atmos. Chem. Phys. Discuss., 11, C11635–C11643, 2011 “NIGHTTIME OBSERVATION AND CHEMISTRY OF HO IN THE PEARL ACPD 13, C13094–C13102, 2014 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Atmos. Chem. Phys. Discuss., 13, C13094–C13102, 2014 INTERACTIVE COMMENT ON “ATMOSPHERIC BROWN CLOUDS REACH THE ACPD 14, C9811–C9812, 2014 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Atmos. Chem. Phys. Discuss., 14, C9811–C9812, 2014 AEROSOL-CLOUD INTERACTION DETERMINED BY BOTH IN SITU AND Aerosol-cloud interaction determined by both in situ and satellite data over a northern high-latitude site H. Lihavainen1, V.-M. Kerminen1 and L.A. Remer2 1Finnish Meteorological Institute, P.O. Box 503, FI-00101, Helsinki, Finland 2 NASA Goddard Space Flight Center, Greenbelt, MD, 20771, USA Abstract The first aerosol indirect effect over a clean, northern high-latitude site was investigated

AUTHOR COMMENT 1

3 1 Also, the first line in the Table 3 key says SC is the critical saturation (sc = SC + 1) in STN 2 and is comparable to SCk (=sck -1) in HYB.It should say SC is the critical supersaturation 3 (sc =SC +1) in STN and is comparable to SCk (=sck -1) in HYB. 4 Thank you for your correction. Yes, you are right. We will correct it in the revised 5

manuscript.

RESPONSE TO COMMENTS BY ANONYMOUS REFEREE #1 R#1-2 “PM2.5 element data (i.e. Silicon) used in this study was obtained from the Teflon filters through analysis using an energy dispersive X-ray fluorescence spectrometer (ED-XRF, Epsilin 5, ACPD - AVERAGE MOLECULAR WEIGHT OF SURFACTANTS IN AEROSOLS9 Abstract. Surfactants in atmospheric aerosols determined as methylene blue active substances (MBAS) and ethyl violet active substances (EVAS). The MBAS and EVAS concentrations can ACPD - ABSORPTION, SCATTERING AND SINGLE SCATTERING ALBEDO8 Abstract. In situ measurements of aerosol optical properties were made in summer 2008 at the ALOMAR station facility (69°16 N, 16°00 E), located at a rural site in the North of THE RATIO OF NO2/NOX DIRECTLY EMITTED FROM VEHICLES ACPD 5, 12723–12740, 2005 The ratio of NO2/NOx directly emitted from vehicles X. Yao et al. Title Page Abstract Introduction Conclusions References Tables Figures ATMOSPHERIC INTERACTIVE COMMENT ON “TEMPERATURE ANDAND PHYSICS ACPD 11, C1065–C1067, 2011 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Page 3675 3 line 3.0 g l-1 should be 3.0 ng l-1 ATMOSPHERIC CHEMISTRY INTERACTIVE COMMENT ON ACPD 12, C5207–C5211, 2012 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Atmos. Chem. Phys. Discuss., 12, C5207–C5211, 2012 ATMOSPHERIC INTERACTIVE CHEMISTRY INTERACTIVE COMMENT ON ACPD 11, C11635–C11643, 2011 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Atmos. Chem. Phys. Discuss., 11, C11635–C11643, 2011 “NIGHTTIME OBSERVATION AND CHEMISTRY OF HO IN THE PEARL ACPD 13, C13094–C13102, 2014 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Atmos. Chem. Phys. Discuss., 13, C13094–C13102, 2014 ACPD - AVERAGE MOLECULAR WEIGHT OF SURFACTANTS IN AEROSOLS9 Abstract. Surfactants in atmospheric aerosols determined as methylene blue active substances (MBAS) and ethyl violet active substances (EVAS). The MBAS and EVAS concentrations can ACPD - ABSORPTION, SCATTERING AND SINGLE SCATTERING ALBEDO8 Abstract. In situ measurements of aerosol optical properties were made in summer 2008 at the ALOMAR station facility (69°16 N, 16°00 E), located at a rural site in the North of THE RATIO OF NO2/NOX DIRECTLY EMITTED FROM VEHICLES ACPD 5, 12723–12740, 2005 The ratio of NO2/NOx directly emitted from vehicles X. Yao et al. Title Page Abstract Introduction Conclusions References Tables Figures ATMOSPHERIC INTERACTIVE COMMENT ON “TEMPERATURE ANDAND PHYSICS ACPD 11, C1065–C1067, 2011 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Page 3675 3 line 3.0 g l-1 should be 3.0 ng l-1 ATMOSPHERIC CHEMISTRY INTERACTIVE COMMENT ON ACPD 12, C5207–C5211, 2012 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Atmos. Chem. Phys. Discuss., 12, C5207–C5211, 2012 ATMOSPHERIC INTERACTIVE CHEMISTRY INTERACTIVE COMMENT ON ACPD 11, C11635–C11643, 2011 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Atmos. Chem. Phys. Discuss., 11, C11635–C11643, 2011 “NIGHTTIME OBSERVATION AND CHEMISTRY OF HO IN THE PEARL ACPD 13, C13094–C13102, 2014 Interactive Comment Full Screen / Esc Printer-friendly Version Interactive Discussion Discussion Paper Atmos. Chem. Phys. Discuss., 13, C13094–C13102, 2014

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The following lists the preprints and final revised papers published within the last 30 days. All papers Final revised papers only Preprints only 24 Apr 2020 Influx of African biomass burning aerosol during the Amazonian dry season through layered transatlantic transport of black

carbon-rich smoke

Bruna A. Holanda, Mira L. Pöhlker, David Walter, Jorge Saturno, Matthias Sörgel, Jeannine Ditas, Florian Ditas, Christiane Schulz, Marco Aurélio Franco, Qiaoqiao Wang, Tobias Donth, Paulo Artaxo, Henrique M. J. Barbosa, Stephan Borrmann, Ramon Braga, Joel Brito, Yafang Cheng, Maximilian Dollner, Johannes W. Kaiser, Thomas Klimach, Christoph Knote, Ovid O. Krüger, Daniel Fütterer, Jošt V. Lavrič, Nan Ma, Luiz A. T. Machado, Jing Ming, Fernando G. Morais, Hauke Paulsen, Daniel Sauer, Hans Schlager, Johannes Schneider, Hang Su, Bernadett Weinzierl, Adrian Walser, Manfred Wendisch, Helmut Ziereis, Martin Zöger, Ulrich Pöschl, Meinrat O. Andreae, and Christopher

Pöhlker

Atmos. Chem. Phys., 20, 4757–4785, https://doi.org/10.5194/acp-20-4757-2020,https://doi.org/10.5194/acp-20-4757-2020,

2020 Short summary

Short summary

Biomass burning smoke from African savanna and grassland is transported across the South Atlantic Ocean in defined layers within the free troposphere. The combination of in situ aircraft and ground-based measurements aided by satellite observations showed that these layers are transported into the Amazon Basin during the early dry season. The influx of aged smoke, enriched in black carbon and cloud condensation nuclei, has important implications for the Amazonian aerosol and cloud cycling.

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24 Apr 2020 The acidity of atmospheric particles and clouds Havala O. T. Pye, Athanasios Nenes, Becky Alexander, Andrew P. Ault, Mary C. Barth, Simon L. Clegg, Jeffrey L. Collett Jr., Kathleen M. Fahey, Christopher J. Hennigan, Hartmut Herrmann, Maria Kanakidou, James T. Kelly, I-Ting Ku, V. Faye McNeill, Nicole Riemer, Thomas Schaefer, Guoliang Shi, Andreas Tilgner, John T. Walker, Tao Wang, Rodney Weber, Jia Xing, Rahul A. Zaveri, and Andreas Zuend Atmos. Chem. Phys., 20, 4809–4888, https://doi.org/10.5194/acp-20-4809-2020,https://doi.org/10.5194/acp-20-4809-2020,

2020 Short summary

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Acid rain is recognized for its impacts on human health and ecosystems, and programs to mitigate these effects have had implications for atmospheric acidity. Historical measurements indicate that cloud and fog droplet acidity has changed in recent decades in response to controls on emissions from human activity, while the limited trend data for suspended particles indicate acidity may be relatively constant. This review synthesizes knowledge on the acidity of atmospheric particles and clouds.

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24 Apr 2020 Trends and emissions of six perfluorocarbons in the Northern Hemisphere and Southern Hemisphere Elise S. Droste, Karina E. Adcock, Matthew J. Ashfold, Charles Chou, Zoë Fleming, Paul J. Fraser, Lauren J. Gooch, Andrew J. Hind, Ray L. Langenfelds, Emma Leedham Elvidge, Norfazrin Mohd Hanif, Simon O'Doherty, David E. Oram, Chang-Feng Ou-Yang, Marios Panagi, Claire E. Reeves, William T. Sturges, and Johannes C. Laube Atmos. Chem. Phys., 20, 4787–4807, https://doi.org/10.5194/acp-20-4787-2020,https://doi.org/10.5194/acp-20-4787-2020,

2020 Short summary

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We update the tropospheric trends and emissions of six perfluorocarbon (PFC) gases, including separate isomers. Trends for these strong greenhouse gases are still increasing, but at slower rates than previously. The lack of natural sinks results in the global accumulation of 833 million metric tonnes of CO2 equivalent for these six PFCs by 2017. Modelling results indicate potential source regions and types in East Asia, but we find that many emissions are unaccounted for in emission reports.

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24 Apr 2020 Effects of global ship emissions on European air

pollution levels

Jan Eiof Jonson, Michael Gauss, Michael Schulz, Jukka-Pekka Jalkanen,

and Hilde Fagerli

Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-293,https://doi.org/10.5194/acp-2020-293,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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We have calculated the effects of air pollution in Europe from shipping on levels of PM2.5 and ozone, and deposition of oxidised nitrogen and sulfur from individual sea areas and from all global shipping. Model results are shown for Europe as a whole but also focusing on selected, mainly coastal, countries. Calculations are made using 2017 emissions, supplemented by calculations reducing sulfur emissions from ships by about 80 % following the implementation of the 2020 global sulfur cap.

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24 Apr 2020 On the role of trend and variability of hydroxyl radical (OH) in the global methane budget Yuanhong Zhao, Marielle Saunois, Philippe Bousquet, Xin Lin, Antoine Berchet, Michaela I. Hegglin, Josep G. Canadell, Robert B. Jackson, Makoto Deushi, Patrick Jöckel, Douglas Kinnison, Ole Kirner, Sarah Strode, Simone Tilmes, Edward J. Dlugokencky, and Bo Zheng Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-308,https://doi.org/10.5194/acp-2020-308,

2020

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Decadal trends and variations in the OH are critical for understanding the atmospheric CH4 evolution. We quantify the impacts of OH trends and variations on the CH4 budget by conducting CH4 inversions on decadal-scale with an ensemble of OH fields. We find the negative OH anomalies due to enhanced fires can reduce the optimized CH4 emissions by up to 10 Tg yr−1 during El Niño years, and the positive OH trend from 1986 to 2010 results in ~ 23 Tg yr−1 additional increase in optimized CH4 emissions.

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24 Apr 2020 Linking global terrestrial CO2 fluxes and environmental drivers using OCO-2 and a geostatistical inverse model Zichong Chen, Junjie Liu, Daven K. Henze, Deborah N. Huntzinger, Kelley C. Wells, and Scot M. Miller Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-285,https://doi.org/10.5194/acp-2020-285,

2020

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NASA's Orbiting Carbon Observatory 2 (OCO-2) satellite observes atmospheric CO2 globally. We explore whether we can use these observations to make connections between CO2 fluxes and environmental variables. We find a combination of temperature, precipitation, and photosynthetically active radiation can substantially describe the variability in CO2 fluxes. However, additional environmental variables are not selected because many variables are correlated when passed through an atmospheric model.

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24 Apr 2020 Understanding Processes that Control Dust Spatial Distributions with Global Climate Models and Satellite Observations Mingxuan Wu, Xiaohong Liu, Hongbin Yu, Hailong Wang, Yang Shi, Kang Yang, Anton Darmenov, Chenglai Wu, Zhien Wang, Tao Luo, Yan Feng, and

Ziming Ke

Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-160,https://doi.org/10.5194/acp-2020-160,

2020

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The spatiotemporal distributions of dust aerosol simulated by global climate models (GCMs) are highly uncertain. In this study, we evaluate dust extinction profiles, optical depth, and surface concentrations simulated in four GCMs, including one reanalysis model, against multiple satellite retrievals and surface observations to gain process-level understanding. Our results highlight the importance of correctly representing dust emission, dry/wet deposition, and size distribution in GCMs.

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24 Apr 2020 Large-scale ion generation for precipitation of atmospheric aerosols Shaoxiang Ma, He Cheng, Jiacheng Li, Maoyuan Xu, Dawei Liu, and Kostya

Ostrikov

Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-23,https://doi.org/10.5194/acp-2020-23,

2020

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Our work suggests that the large corona discharge system is an efficient and possibly economically sustainable way to increase the ion density in the open air and control precipitation of atmospheric aerosols. Once the system is installed on the mountain top, it will generate lots of charged nuclei, which may trigger water precipitation or fog elimination within a certain region in the downwind directions.

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23 Apr 2020 Revisiting global satellite observations of stratospheric

cirrus clouds

Ling Zou, Sabine Griessbach, Lars Hoffmann, Bing Gong, and Lunche Wang Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-304,https://doi.org/10.5194/acp-2020-304,

2020

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Cirrus clouds appearing in the upper troposphere and lower stratosphere have important impacts on the radiation budget and climate change. We revisited global stratospheric cirrus clouds from CALIPSO and for first time with MIPAS satellite observations. Stratospheric cirrus clouds related to deep convection are frequently detected in the tropics. At middle latitudes, MIPAS detects more than twice as many stratospheric cirrus clouds due to higher detection

sensitivity.

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23 Apr 2020 Kinetics of dimethyl sulfide (DMS) reactions with isoprene-derived Criegee intermediates studied with direct UV

absorption

Mei-Tsan Kuo, Isabelle Weber, Christa Fittschen, and Jim Jr-Min Lin Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-326,https://doi.org/10.5194/acp-2020-326,

2020

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Dimethyl sulfide (DMS) is the major sulfur-containing species in the troposphere. Previous work by Newland et al. reported very high reactivity of isoprene-derived Criegee intermediates (CIs) towards DMS. By monitoring CIs with direct UV absorption, we found CI + DMS reactions are very slow, in contrast to the results of Newland et al., suggesting these CIs would not oxidize atmospheric DMS at any substantial level.

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23 Apr 2020 North African mineral dust sources: new insights from a combined analysis based on 3D dust aerosols distributions, surface winds and ancillary soil parameters Sophie Vandenbussche, Sieglinde Callewaert, Kerstin Schepanski, and

Martine De Mazière

Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-130,https://doi.org/10.5194/acp-2020-130,

2020

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Mineral dust aerosols blown mostly from desert areas are a key player in the climate system. We use a new data set of desert dust aerosols low altitude concentration together with additional information on the surface state and low altitude winds to infer desert dust emission and source maps over north Africa. With 9 years of data, we observe a full seasonal cycle of dust emissions, differentiating morning and afternoon / evening emissions and providing a first glance at

long-term changes.

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22 Apr 2020 Overview of aerosol optical properties over southern West Africa from DACCIWA aircraft measurements Cyrielle Denjean, Thierry Bourrianne, Frederic Burnet, Marc Mallet, Nicolas Maury, Aurélie Colomb, Pamela Dominutti, Joel Brito, Régis Dupuy, Karine Sellegri, Alfons Schwarzenboeck, Cyrille Flamant, and

Peter Knippertz

Atmos. Chem. Phys., 20, 4735–4756, https://doi.org/10.5194/acp-20-4735-2020,https://doi.org/10.5194/acp-20-4735-2020,

2020 Short summary

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This paper presents aircraft measurements of aerosol optical properties over southern West Africa. We show that aerosol optical properties in the boundary layer were dominated by a persistent biomass burning loading from the Southern Hemisphere. Biomass burning aerosols were more light absorbing that those previously measured in other areas (Amazonia, North America). Our study suggests that lens-coated black carbon particles were the dominant absorber for these biomass burning aerosols.

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22 Apr 2020 Influence of vessel characteristics and atmospheric processes on the gas and particle phase of ship emission plumes: in situ measurements in the Mediterranean Sea and around the Arabian

Peninsula

Siddika Celik, Frank Drewnick, Friederike Fachinger, James Brooks, Eoghan Darbyshire, Hugh Coe, Jean-Daniel Paris, Philipp G. Eger, Jan Schuladen, Ivan Tadic, Nils Friedrich, Dirk Dienhart, Bettina Hottmann, Horst Fischer, John N. Crowley, Hartwig Harder, and Stephan

Borrmann

Atmos. Chem. Phys., 20, 4713–4734, https://doi.org/10.5194/acp-20-4713-2020,https://doi.org/10.5194/acp-20-4713-2020,

2020 Short summary

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Analysis of 252 ship emission plumes in the Mediterranean Sea and around the Arabian Peninsula examined particulate- and gas-phase characteristics. By identifying the corresponding ships, source features and plume age were determined. Emission factors (amount of pollutant per kilogram of fuel burned) were calculated and investigated for dependencies on source characteristics, atmospheric conditions, and transport time, providing insight into the most relevant influences on ship emissions.

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22 Apr 2020 Satellite-based radiative forcing by light-absorbing particles in snow across the Northern Hemisphere Jiecan Cui, Tenglong Shi, Yue Zhou, Dongyou Wu, Xin Wang, and Wei Pu Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-50,https://doi.org/10.5194/acp-2020-50,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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We make the first quantitative, remote-sensing-based and hemisphere-scale assessment of radiative forcing (RF) due to Light-absorbing particles (LAPs) in snow. We observed significant spatial variations in snow albedo reduction and RF due to LAPs throughout the Northern Hemisphere, with the lowest values occurring in the Arctic and the highest in northeastern China. We determined that the LAPs in snow play a critical role in spatial variability in Northern Hemisphere albedo reduction and RF.

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22 Apr 2020 The trend of the oxidants in boreal forest over 2007–2018: comprehensive modelling study with long-term measurements at SMEAR II, Finland Dean Chen, Putian Zhou, Tuomo Nieminen, Pontus Roldin, Ximeng Qi, Petri Clusius, Carlton Xavier, Lukas Pichelstorfer, Markku Kulmala, Pekka Rantala, Juho Aalto, Nina Sarnela, Pasi Kolari, Petri Keronen, Matti P. Rissanen, Metin Baykara, and Michael Boy Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-128,https://doi.org/10.5194/acp-2020-128,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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Atmospheric oxidants OH, O3 and NO3 dominate the atmospheric oxidation capacity, and sulfuric acid (H2SO4) is considered as a main driver for new particle formation events. We studied how the trends of these atmospheric oxidants and H2SO4 changed in southern Finland during the past 12 years and discussed how these trends related to decreasing emissions of air pollutants in Europe. Our results showed that OH increased by 1.56 % yr−1 at daytime and NO3 decreased by 3.92 % yr−1 at nighttime.

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22 Apr 2020 Rate coefficients for reactions of OH with aromatic and aliphatic volatile organic compounds determined by the Multivariate Relative Rate Technique Jacob T. Shaw, Andrew R. Rickard, Mike J. Newland, and Terry J. Dillon Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-281,https://doi.org/10.5194/acp-2020-281,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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This work expands upon the recently developed multivariate relative rate technique, presented in Shaw et al. (2019), for the measurement of rates of reaction between important aromatic and aliphatic VOCs and OH. Knowledge of the rates of such reactions are important for understanding air quality developments in urban environments. This work also provides an important validation for structure activity relationship models, which provide a theoretical method for estimating

OH + VOC kinetics.

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22 Apr 2020 Snow heterogeneous reactivity of bromide with ozone lost during snow metamorphism Jacinta Edebeli, Jürg C. Trachsel, Sven E. Avak, Markus Ammann, Martin Schneebeli, Anja Eichler, and Thorsten Bartels-Rausch Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-170,https://doi.org/10.5194/acp-2020-170,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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Earth’s snow cover is very dynamic and can change its physical properties within hours, as is well known by skiers. Snow is also known as a host for chemical reactions the products of which impact air composition and quality. Here, we present laboratory experiments that show how the dynamics of snow (metamorphism) make snow essential uncreative towards gas-phase ozone with time despite its content of reactive chemicals. Impacts on polar atmospheric chemistry are

discussed.

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21 Apr 2020 Characterization of organic aerosol across the global remote troposphere: a comparison of ATom measurements and global

chemistry models

Alma Hodzic, Pedro Campuzano-Jost, Huisheng Bian, Mian Chin, Peter R. Colarco, Douglas A. Day, Karl D. Froyd, Bernd Heinold, Duseong S. Jo, Joseph M. Katich, John K. Kodros, Benjamin A. Nault, Jeffrey R. Pierce, Eric Ray, Jacob Schacht, Gregory P. Schill, Jason C. Schroder, Joshua P. Schwarz, Donna T. Sueper, Ina Tegen, Simone Tilmes, Kostas Tsigaridis, Pengfei Yu, and Jose L. Jimenez Atmos. Chem. Phys., 20, 4607–4635, https://doi.org/10.5194/acp-20-4607-2020,https://doi.org/10.5194/acp-20-4607-2020,

2020 Short summary

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Organic aerosol (OA) is a key source of uncertainty in aerosol climate effects. We present the first pole-to-pole OA characterization during the NASA Atmospheric Tomography aircraft mission. OA has a strong seasonal and zonal variability, with the highest levels in summer and over fire-influenced regions and the lowest ones in the southern high latitudes. We show that global models predict the OA distribution well but not the relative contribution of OA emissions vs. chemical production.

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21 Apr 2020 The evolutionary behavior of chromophoric brown carbon during ozone aging of fine particles from biomass burning Xingjun Fan, Tao Cao, Xufang Yu, Yan Wang, Xin Xiao, Feiyue Li, Yue Xie, Wenchao Ji, Jianzhong Song, and Ping'an Peng Atmos. Chem. Phys., 20, 4593–4605, https://doi.org/10.5194/acp-20-4593-2020,https://doi.org/10.5194/acp-20-4593-2020,

2020 Short summary

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A particle-phase O3 oxidation of biomass burning (BB) smoke particles was conducted to investigate the evolution of brown carbon (BrC) therein. The O3 aging induced the decomposition of chromophores and fluorophores. EEM–PARAFAC showed a predominant decomposition of protein-like substances and a gradual increase proportion of humic-like substances for BB BrC during O3 aging. The dynamic spectral behavior of chromophores and functional groups within BrC was further

explored by 2D-COS.

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21 Apr 2020 The combined effect of two westerly jet waveguides on heavy haze in the North China Plain in November and December 2015 Xiadong An, Lifang Sheng, Qian Liu, Chun Li, Yang Gao, and Jianping Li Atmos. Chem. Phys., 20, 4667–4680, https://doi.org/10.5194/acp-20-4667-2020,https://doi.org/10.5194/acp-20-4667-2020,

2020 Short summary

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Severe haze occurred in the North China Plain (NCP) in November to December 2015. We found that the two Rossby waveguides within the westerly jet originating from the Mediterranean were responsible for the haze formation in the NCP. The weak East Asia winter monsoon and anomalous circulation with ascending motion over southern China and descending motion over the NCP related to the two Rossby waveguides, which modulated haze accumulation and favored the maintenance of

severe haze.

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21 Apr 2020 Soccer games and record-breaking PM2.5 pollution events

in Santiago, Chile

Rémy Lapere, Laurent Menut, Sylvain Mailler, and Nicolás Huneeus Atmos. Chem. Phys., 20, 4681–4694, https://doi.org/10.5194/acp-20-4681-2020,https://doi.org/10.5194/acp-20-4681-2020,

2020 Short summary

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Based on measurements and modeling, this study shows that recent record-breaking peak events of fine particles in Santiago, Chile, can be traced back to massive barbecue cooking by its inhabitants during international soccer games. Decontamination plans in Santiago focus on decreasing emissions of pollutants from traffic, industry, and residential heating. This study implies that cultural habits such as barbecue cooking also need to be taken into account.

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21 Apr 2020 Long-term profiling of aerosol light extinction, particle mass, cloud condensation nuclei, and ice-nucleating particle concentration over Dushanbe, Tajikistan, in Central Asia Julian Hofer, Albert Ansmann, Dietrich Althausen, Ronny Engelmann, Holger Baars, Sabur F. Abdullaev, and Abduvosit N. Makhmudov Atmos. Chem. Phys., 20, 4695–4711, https://doi.org/10.5194/acp-20-4695-2020,https://doi.org/10.5194/acp-20-4695-2020,

2020 Short summary

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For the first time, continuous, vertically resolved long-term aerosol measurements were conducted with a state-of-the-art multiwavelength lidar over a Central Asian site. Such observations are urgently required in efforts to predict future climate and environmental conditions and to support spaceborne remote sensing (ground truth

activities).

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21 Apr 2020 Stratocumulus cloud clearings: statistics from satellites, reanalysis models, and airborne measurements Hossein Dadashazar, Ewan Crosbie, Mohammad S. Majdi, Milad Panahi, Mohammad A. Moghaddam, Ali Behrangi, Michael Brunke, Xubin Zeng, Haflidi H. Jonsson, and Armin Sorooshian Atmos. Chem. Phys., 20, 4637–4665, https://doi.org/10.5194/acp-20-4637-2020,https://doi.org/10.5194/acp-20-4637-2020,

2020 Short summary

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Clearings in the marine-boundary-layer (MBL) cloud deck of the Pacific Ocean were studied. Remote sensing, reanalysis, and airborne data were used along with machine-learning modeling to characterize the spatiotemporal nature of clearings and factors governing their growth. The most significant implications of our results are linked to modeling of fog and MBL clouds, with implications for societal and environmental issues like climate, military operations, transportation, and coastal ecology.

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21 Apr 2020 Haze pollution under a high atmospheric oxidization capacity in summer in Beijing: insights into formation mechanism of atmospheric physicochemical processes Dandan Zhao, Guangjing Liu, Jinyuan Xin, Jiannong Quan, Yuesi Wang, Xin Wang, Lindong Dai, Wenkang Gao, Guiqian Tang, Bo Hu, Yongxiang Ma, Xiaoyan Wu, Lili Wang, Zirui Liu, and Fangkun Wu Atmos. Chem. Phys., 20, 4575–4592, https://doi.org/10.5194/acp-20-4575-2020,https://doi.org/10.5194/acp-20-4575-2020,

2020 Short summary

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Under strong atmospheric oxidization capacity, haze pollution in the summer in Beijing was the result of the synergistic effect of the physicochemical process in the atmospheric boundary layer (ABL). With the premise of an extremely stable ABL structure, the formation of secondary aerosols dominated by nitrate was quite intense, driving the outbreak of haze pollution.

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21 Apr 2020 Surface–atmosphere fluxes of volatile organic compounds

in Beijing

W. Joe F. Acton, Zhonghui Huang, Brian Davison, Will S. Drysdale, Pingqing Fu, Michael Hollaway, Ben Langford, James Lee, Yanhui Liu, Stefan Metzger, Neil Mullinger, Eiko Nemitz, Claire E. Reeves, Freya A. Squires, Adam R. Vaughan, Xinming Wang, Zhaoyi Wang, Oliver Wild, Qiang Zhang, Yanli Zhang, and C. Nicholas Hewitt Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-343,https://doi.org/10.5194/acp-2020-343,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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Air quality in Beijing is of concern to both policy makers and the general public. In order to address concerns about air quality it is vital that the sources of atmospheric pollutants are understood. This work presents the first top-down measurement of volatile organic compound (VOC) emissions in Beijing. These measurements are used to validate the emissions inventory and assess the impact of VOC emission from the city centre on atmospheric chemistry.

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21 Apr 2020 Errors in top-down estimates of emissions using a known

source

Wayne M. Angevine, Jeff Peischl, Alice Crawford, Christopher P. Loughner, Ilana B. Pollack, and Chelsea R. Thompson Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-169,https://doi.org/10.5194/acp-2020-169,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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Emissions of air pollutants must be known for a wide variety of application. Different methods of estimating emissions often disagree substantially. In this study, we apply standard methods to a well-known source, a power plant. We explore the uncertainty implied by the different answers that come from the different methods, different samples taken over several years, and different pollutants. We find that the overall uncertainty of emissions estimates is about

30 %.

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21 Apr 2020 Heterogeneous nucleation of water vapor on different types of black carbon particles Ari Laaksonen, Jussi Malila, and Athanasios Nenes Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-202,https://doi.org/10.5194/acp-2020-202,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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Aerosol particles containing black carbon are ubiquitos in the atmosphere, and originate from combustion processes. We examine their capability to act as condensation centers for water vapor. We make use of published experimental data sets for different types of black carbon particles, ranging from very pure particles to particles that contain both black carbon and water soluble organic matter, and show that a recently developed theory reproduces most of the experimental

results.

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21 Apr 2020 Investigating emission sources and transport of aerosols in Siberia using airborne and spaceborne LIDAR measurements Antonin Zabukovec, Gerard Ancellet, Iwan E. Penner, Mikhail Arshinov, Valery Kozlov, Jacques Pelon, Jean-Daniel Paris, Grigory Kokhanenko, Yuri S. Balin, Dmitry Chernov, and Boris D. Belan Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-195,https://doi.org/10.5194/acp-2020-195,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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Description of two aircraft campaigns results carried out over Siberia in 2013 and 2017 to characterize aerosol emission. A methodology is proposed to derive the aerosol types using transport model and satellite observations. The extinction to backscatter ratio for each aerosol types is reported as it is a key parameter to constrain their radiative impact. These results are compared to previous work conducted in other regions and to aerosol data products observed by spaceborne lidars.

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20 Apr 2020 Seasonal source variability of carbonaceous aerosols at the Rwanda Climate Observatory August Andersson, Elena N. Kirillova, Stefano Decesari, Langley DeWitt, Jimmy Gasore, Katherine E. Potter, Ronald G. Prinn, Maheswar Rupakheti, Jean de Dieu Ndikubwimana, Julius Nkusi, and Bonfils Safari Atmos. Chem. Phys., 20, 4561–4573, https://doi.org/10.5194/acp-20-4561-2020,https://doi.org/10.5194/acp-20-4561-2020,

2020 Short summary

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Large-scale biomass burning events seasonally cover sub-Saharan Africa with air particles. In this study, we find that the concentrations of these particles at a remote mountain site in Rwanda may increase by a factor of 10 during such dry biomass burning periods, with strong implications for the regional climate and human health. These results provide quantitative constraints that could contribute to reducing the large uncertainties regarding the environmental impact of these fires.

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20 Apr 2020 Comprehensive analyses of source sensitivities to and apportionments of PM2.5 and ozone over Japan via multiple numerical

techniques

Satoru Chatani, Hikari Shimadera, Syuichi Itahashi, and Kazuyo Yamaji Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-236,https://doi.org/10.5194/acp-2020-236,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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Source sensitivities and apportionments of PM2.5 and ozone concentrations over Japan for 2016 were evaluated using multiple numerical techniques including BFM, HDDM, and ISAM, embedded in regional chemical transport models. Influences of stringent emission controls recently implemented in Asian countries were reflected. Differences between sensitivities and apportionments greatly helped distinguishing various direct and indirect effects of emission sources on PM2.5 and ozone concentrations.

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20 Apr 2020 Rapid Evolution of Aerosol Particles and their Optical Properties Downwind of Wildfires in the Western U.S. Lawrence I. Kleinman, Arthur J. Sedlacek III, Kouji Adachi, Peter R. Buseck, Sonya Collier, Manvendra K. Dubey, Anna L. Hodshire, Ernie Lewis, Timothy B. Onasch, Jeffery R. Pierce, John Shilling, Stephen R. Springston, Jian Wang, Qi Zhang, Shan Zhou, and Robert J. Yokelson Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-239,https://doi.org/10.5194/acp-2020-239,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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Aerosols from wildfires effect the Earth's temperature by absorbing light or reflecting it back into space. This study investigates time-dependent chemical, microphysical, and optical properties of aerosols generated by wildfires in the Pacific Northwest, USA. Wildfire smoke plumes were traversed by an instrumented aircraft at locations near the fire and up to 3.5-hour travel time downwind. Although there was no net aerosol production, aerosol particles grew and became more efficient scatters.

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20 Apr 2020 A plasmachemical axially symmetric self-consistent model

of daytime sprite

Andrey Evtushenko, Fedor Kuterin, and Ekaterina Svechnikova Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2019-1196,https://doi.org/10.5194/acp-2019-1196,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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The paper presents the results of self-consistent axially symmetric modelling of a daytime sprite. Perturbations of the concentrations of ions, neutral compounds, excited atoms and molecules along with disturbances of the electric field are studied. The possibility of the initiation of a daytime sprite by an extremely intense lightning discharge leading to a significant long-term perturbation of atmospheric chemical balance is demonstrated.

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17 Apr 2020 Background heterogeneity and other uncertainties in estimating urban methane flux: results from the Indianapolis Flux

Experiment (INFLUX)

Nikolay V. Balashov, Kenneth J. Davis, Natasha L. Miles, Thomas Lauvaux, Scott J. Richardson, Zachary R. Barkley, and Timothy A. Bonin Atmos. Chem. Phys., 20, 4545–4559, https://doi.org/10.5194/acp-20-4545-2020,https://doi.org/10.5194/acp-20-4545-2020,

2020 Short summary

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An accurate independent verification methodology to estimate methane (a powerful greenhouse gas) emissions is essential for the effective implementation of policies that aim to reduce the impacts of climate change. In this paper, four uncertainties that complicate the independent estimation of urban methane emissions are identified: the definition of urban domain, background heterogeneity, emissions temporal variability, and missing sources. Ways to improve emission estimates are suggested.

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17 Apr 2020 Variability in cirrus cloud properties using a PollyXT Raman lidar over high and tropical latitudes Kalliopi Artemis Voudouri, Elina Giannakaki, Mika Komppula, and

Dimitris Balis

Atmos. Chem. Phys., 20, 4427–4444, https://doi.org/10.5194/acp-20-4427-2020,https://doi.org/10.5194/acp-20-4427-2020,

2020 Short summary

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In this paper we present the variability in cirrus cloud properties using a PollyXT Raman lidar over high and tropical latitudes. The kind of information presented here can be rather useful in the cirrus parameterisations required as input to radiative transfer models and can be a complementary tool for satellite products that cannot provide cloud vertical structure.

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17 Apr 2020 Effects of SO2 on optical properties of secondary organic aerosol generated from photooxidation of toluene under different relative humidity conditions Wenyu Zhang, Weigang Wang, Junling Li, Chao Peng, Kun Li, Li Zhou, Bo Shi, Yan Chen, Mingyuan Liu, and Maofa Ge Atmos. Chem. Phys., 20, 4477–4492, https://doi.org/10.5194/acp-20-4477-2020,https://doi.org/10.5194/acp-20-4477-2020,

2020 Short summary

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We investigated the effect of SO2 under different humidities on optical properties of toluene-derived SOA under four conditions with CRDs and PAX at 532 and 375 nm, respectively. Our results showed that SO2 under different humidities can change the refractive complex index of toluene SOA by influencing the multiphase processes and altering the aerosol chemical compositions. Different atmospheric conditions could affect the properties of toluene SOA, as well as the global radiative balance.

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17 Apr 2020 Global response of parameterised convective cloud fields to anthropogenic aerosol forcing Zak Kipling, Laurent Labbouz, and Philip Stier Atmos. Chem. Phys., 20, 4445–4460, https://doi.org/10.5194/acp-20-4445-2020,https://doi.org/10.5194/acp-20-4445-2020,

2020

17 Apr 2020 Evaluation of the CAMS global atmospheric trace gas reanalysis 2003–2016 using aircraft campaign observations Yuting Wang, Yong-Feng Ma, Henk Eskes, Antje Inness, Johannes Flemming, and Guy P. Brasseur Atmos. Chem. Phys., 20, 4493–4521, https://doi.org/10.5194/acp-20-4493-2020,https://doi.org/10.5194/acp-20-4493-2020,

2020 Short summary

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The paper presents an evaluation of the CAMS global reanalysis of reactive gases performed for the period 2003–2016. The evaluation is performed by comparing concentrations of chemical species gathered during airborne field campaigns with calculated values. The reanalysis successfully reproduces the observed concentrations of ozone and carbon monoxide but generally underestimates the abundance of hydrocarbons. Large discrepancies exist for fast-reacting radicals

such as OH and HO2.

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17 Apr 2020 On the annual variability of Antarctic aerosol size distributions at Halley Research Station Thomas Lachlan-Cope, David C. S. Beddows, Neil Brough, Anna E. Jones, Roy M. Harrison, Angelo Lupi, Young Jun Yoon, Aki Virkkula, and Manuel

Dall'Osto

Atmos. Chem. Phys., 20, 4461–4476, https://doi.org/10.5194/acp-20-4461-2020,https://doi.org/10.5194/acp-20-4461-2020,

2020 Short summary

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We present a statistical cluster analysis of the physical characteristics of particle size distributions collected at Halley (Antarctica) for the year 2015. Complex interactions between multiple ecosystems, coupled with different atmospheric circulation, result in very different aerosol size distributions populating the Southern

Hemisphere.

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17 Apr 2020 Atmospheric energy budget response to idealized aerosol perturbation in tropical cloud systems Guy Dagan, Philip Stier, Matthew Christensen, Guido Cioni, Daniel Klocke, and Axel Seifert Atmos. Chem. Phys., 20, 4523–4544, https://doi.org/10.5194/acp-20-4523-2020,https://doi.org/10.5194/acp-20-4523-2020,

2020 Short summary

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In order to better understand the physical processes behind aerosol effects on the atmospheric energy budget, we analyse numerical simulations of tropical cloud systems. Two sets of simulations, at different dates during the NARVAL 2 field campaign, are simulated with different dominant cloud modes. Our results demonstrate that under different environmental conditions, the response of the atmospheric energy budget to aerosol perturbation could be different.

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17 Apr 2020 Absorption closure in highly aged biomass burning smoke Jonathan W. Taylor, Huihui Wu, Kate Szpek, Keith Bower, Ian Crawford, Michael J. Flynn, Paul I. Williams, James Dorsey, Justin M. Langridge, Michael I. Cotterell, Cathryn Fox, Nicholas W. Davies, Jim M. Haywood,

and Hugh Coe

Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-333,https://doi.org/10.5194/acp-2020-333,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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Every year, huge plumes of smoke hundreds of miles wide travel over the south Atlantic Ocean from fires in central and southern Africa. These plumes absorb the sun’s energy and warm the climate. We measured the properties of the smoke using instruments on board an aircraft, to work out how absorbing the smoke is, and which components of the smoke warm the air the most. We also tested different ways of simulating these properties that could be used in a climate model.

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17 Apr 2020 Measurement report: Characteristics and sources of non-methane VOCs and their roles in SOA formation during autumn in a central Chinese city Haixu Zhang, Chunrong Chen, Weijia Yan, Nana Wu, Yu Bo, Qiang Zhang,

and Kebin He

Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-280,https://doi.org/10.5194/acp-2020-280,

2020

Preprint under review for ACP (discussion: open, 1 comment) Short

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In this work, we provide first-hand information on VOC characters in a central Chinese city. Although benzenoids has the largest SOA formation potential, their weight decline with the aggravation of pollution, while the role of VOCs as oxidant producers of SOA formation is critical, especially in hazy periods. Furthermore, solvent evaporation is estimated as the top source for SOA formation considering the above dual roles of VOCs, which would assist to mitigate pollution in China.

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16 Apr 2020 A revisiting of the parametrization of downward longwave radiation in summer over the Tibetan Plateau based on high-temporal-resolution measurements Mengqi Liu, Xiangdong Zheng, Jinqiang Zhang, and Xiangao Xia Atmos. Chem. Phys., 20, 4415–4426, https://doi.org/10.5194/acp-20-4415-2020,https://doi.org/10.5194/acp-20-4415-2020,

2020 Short summary

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This study uses 1 min radiation and lidar measurements at three stations over the Tibetan Plateau (TP) to parametrize downward longwave radiation (DLR) during summer months. Clear-sky DLR can be estimated from the best parametrization with a RMSE of 3.8 W m-2 and _R_2 > 0.98. Additionally cloud base height under overcast conditions is shown to play an important role in cloudy DLR parametrization, which is considered in the locally calibrated parametrization over the TP for the first time.

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16 Apr 2020 Ozone pollution over China and India: seasonality and

sources

Meng Gao, Jinhui Gao, Bin Zhu, Rajesh Kumar, Xiao Lu, Shaojie Song, Yuzhong Zhang, Beixi Jia, Peng Wang, Gufran Beig, Jianlin Hu, Qi Ying, Hongliang Zhang, Peter Sherman, and Michael B. McElroy Atmos. Chem. Phys., 20, 4399–4414, https://doi.org/10.5194/acp-20-4399-2020,https://doi.org/10.5194/acp-20-4399-2020,

2020 Short summary

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A regional fully coupled meteorology–chemistry model, Weather Research and Forecasting model with Chemistry (WRF-Chem), was employed to study the seasonality of ozone (O3) pollution and its sources in both China and India.

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16 Apr 2020 Climatological impact of the Brewer–Dobson Circulation on the N2O budget in WACCM, a chemical reanalysis and a CTM driven by four dynamical reanalyses Daniele Minganti, Simon Chabrillat, Yves Christophe, Quentin Errera, Marta Abalos, Maxime Prignon, Douglas E. Kinnison, and Emmanuel Mahieu Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-262,https://doi.org/10.5194/acp-2020-262,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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The climatology of the N2O transport budget in the stratosphere is studied in the Transformed Eulerian Mean framework across a variety of datasets: a Chemistry-Climate Model, a chemistry transport model driven by four reanalyses, and a chemical reanalysis. The impact of vertical advection on N2O agrees well in the datasets, but horizontal mixing presents large differences above the Antarctic and in the whole Northern Hemisphere.

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16 Apr 2020 2013–2019 increases of surface ozone pollution in China: anthropogenic and meteorological influences Ke Li, Daniel J. Jacob, Lu Shen, Xiao Lu, Isabelle De Smedt, and Hong

Liao

Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-298,https://doi.org/10.5194/acp-2020-298,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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Surface summer ozone has been increasing in China over 2013–2019, despite new governmental efforts targeting ozone pollution. We find the ozone increase is mostly due to anthropogenic drivers, although meteorology also plays a role. Further analysis for North China Plain shows that PM2.5 continued to decrease through 2019 while emissions of volatile organic compounds (VOCs) stayed flat. This can explain the anthropogenic increase in ozone because PM2.5 scavenges the radical precursors of ozone.

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16 Apr 2020 Models transport Saharan dust too low in the atmosphere compared to observations Debbie O'Sullivan, Franco Marenco, Claire L. Ryder, Yaswant Pradhan, Zak Kipling, Ben Johnson, Angela Benedetti, Melissa Brooks, Matthew McGill, John Yorks, and Patrick Selmer Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-57,https://doi.org/10.5194/acp-2020-57,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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Mineral dust is an important component of the climate system, and we assess how well it is predicted by two operational models. We have flown an aircraft in the dust layers in the Eastern Atlantic, and we also make use of satellites. We show that models predict the dust layer too low and that it predicts the particles to be too small. We believe that these discrepancies may be overcome if models can be constrained with better observations of the dust vertical and size-resolved distribution.

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16 Apr 2020 Formation and sink of glyoxal and methylglyoxal in a polluted subtropical environment: observation-based photochemical analysis and impact evaluation Zhenhao Ling, Qianqian Xie, Zhe Wang, Tao Wang, Hai Guo, and Xuemei

Wang

Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-212,https://doi.org/10.5194/acp-2020-212,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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The observation data from a receptor site in the Pearl River Delta region was analyzed by a photochemical box model with near-explicit chemical mechanisms (i.e., the master chemical mechanism, MCM), and improvements with reversible and irreversible heterogeneous processes of Glyoxal and Methylglyoxal, and the gas-particle partitioning of oxidation products in the present study.

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15 Apr 2020 The influence of residential wood combustion on the concentrations of PM2.5 in four Nordic cities Jaakko Kukkonen, Susana López-Aparicio, David Segersson, Camilla Geels, Leena Kangas, Mari Kauhaniemi, Androniki Maragkidou, Anne Jensen, Timo Assmuth, Ari Karppinen, Mikhail Sofiev, Heidi Hellén, Kari Riikonen, Juha Nikmo, Anu Kousa, Jarkko V. Niemi, Niko Karvosenoja, Gabriela Sousa Santos, Ingrid Sundvor, Ulas Im, Jesper H. Christensen, Ole-Kenneth Nielsen, Marlene S. Plejdrup, Jacob Klenø Nøjgaard, Gunnar Omstedt, Camilla Andersson, Bertil Forsberg, and

Jørgen Brandt

Atmos. Chem. Phys., 20, 4333–4365, https://doi.org/10.5194/acp-20-4333-2020,https://doi.org/10.5194/acp-20-4333-2020,

2020 Short summary

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Residential wood combustion can cause substantial emissions of fine particulate matter and adverse health effects. This study has, for the first time, evaluated the impacts of residential wood combustion in a harmonised manner in four Nordic cities. Wood combustion caused major shares of fine particle concentrations in Oslo (up to 60 %) and Umeå (up to 30 %) and also notable shares in Copenhagen (up to 20 %) and Helsinki (up to 15 %).

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15 Apr 2020 Satellite mapping of PM2.5 episodes in the wintertime San Joaquin Valley: a “static” model using column water vapor Robert B. Chatfield, Meytar Sorek-Hamer, Robert F. Esswein, and Alexei

Lyapustin

Atmos. Chem. Phys., 20, 4379–4397, https://doi.org/10.5194/acp-20-4379-2020,https://doi.org/10.5194/acp-20-4379-2020,

2020 Short summary

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There is a great need to define health-affecting pollution by small particles as “respirable aerosol”. The wintertime San Joaquin Valley experiences severe episodes that need full maps. A few air pollution monitors are set out by agencies in such regions. Satellite data on haziness and daily calibration using the monitors map out improved pollution estimates for the winter of 2012–2013. These show patterns of valuable empirical information about sources, transport, and cleanout of pollution.

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15 Apr 2020 Heterogeneous N2O5 reactions on atmospheric aerosols at four Chinese sites: improving model representation of uptake

parameters

Chuan Yu, Zhe Wang, Men Xia, Xiao Fu, Weihao Wang, Yee Jun Tham, Tianshu Chen, Penggang Zheng, Hongyong Li, Ye Shan, Xinfeng Wang, Likun Xue, Yan Zhou, Dingli Yue, Yubo Ou, Jian Gao, Keding Lu, Steven S. Brown, Yuanhang Zhang, and Tao Wang Atmos. Chem. Phys., 20, 4367–4378, https://doi.org/10.5194/acp-20-4367-2020,https://doi.org/10.5194/acp-20-4367-2020,

2020 Short summary

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This study provides a holistic picture of N2O5 heterogeneous uptake on ambient aerosols and the influencing factors under various climatic and chemical conditions in China, and it proposes an observation-based empirical parameterization. The empirical parameterization can be used in air quality models to improve the prediction of PM2.5 and photochemical pollution in China and similar polluted regions of the

world.

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15 Apr 2020 Response of dust emissions in southwestern North America to 21st century trends in climate, CO2 fertilization, and land use: Implications for air quality Yang Li, Loretta J. Mickley, and Jed O. Kaplan Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-311,https://doi.org/10.5194/acp-2020-311,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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Climate models predict a shift toward warmer and drier environments in southwestern North America. Under future climate, the two main drivers of dust trends play opposing roles, with CO2 fertilization enhancing vegetation and thus decreasing dust and with increasing land use enhancing dust emissions from northern Mexico. In the worst-case scenario, elevated dust concentrations spread widely over the domain by 2100 in spring, suggesting a large climate penalty on air quality

and human health.

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14 Apr 2020 Simulation of organic aerosol formation during the CalNex study: updated mobile emissions and secondary organic aerosol parameterization for intermediate-volatility organic compounds Quanyang Lu, Benjamin N. Murphy, Momei Qin, Peter J. Adams, Yunliang Zhao, Havala O. T. Pye, Christos Efstathiou, Chris Allen, and Allen L.

Robinson

Atmos. Chem. Phys., 20, 4313–4332, https://doi.org/10.5194/acp-20-4313-2020,https://doi.org/10.5194/acp-20-4313-2020,

2020 Short summary

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This research work investigates organic aerosol formation in California during the CalNex study. We update the chemical transport model with the most recent mobile-source emission data and introduce a simple parameterization for secondary organic aerosol formed from intermediate-volatility organic compounds. Our results highlight the important contribution of IVOCs to SOA production in the Los Angeles region but underscore that other uncertainties must be addressed to close the SOA mass balance.

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14 Apr 2020 Oligomer and highly oxygenated organic molecule formation from oxidation of oxygenated monoterpenes emitted by California sage

plants

Archit Mehra, Jordan E. Krechmer, Andrew T. Lambe, Chinmoy Sarkar, Farzaneh Khalaj, Alex Guenther, John Jayne, Hugh Coe, Douglas R. Worsnop, Celia Faiola, Manjula R. Canagaratna, and Leah Williams Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-267,https://doi.org/10.5194/acp-2020-267,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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Emissions of volatile organic compounds (VOCs) from plants are important for tropospheric ozone and secondary organic aerosol (SOA) formation. Real plant emissions are much more diverse than the few proxies widely used for studies of plant SOA. Here we present the first study of SOA from California Sage plants and oxygenated monoterpenes representing their major emissions. We identify SOA products and show the importance of formation of highly oxygenated organic molecules (HOM) and oligomers.

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14 Apr 2020 Biomass burning combustion efficiency observed from space using measurements of CO and NO2 by TROPOMI Ivar R. van der Velde, Guido R. van der Werf, Sander Houweling, Henk J. Eskes, J. Pepijn Veefkind, Tobias Borsdorff, and Ilse Aben Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-272,https://doi.org/10.5194/acp-2020-272,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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This paper compares the relative atmospheric enhancements of CO and NO2 measured by the new space-based instrument TROPOMI over different fire-prone ecosystems around the world. We find distinct spatial and temporal patterns in ΔNO2 / ΔCO ratio that correspond to regional differences in combustion efficiency. This joint analysis provides a better understanding of regional scale combustion characteristics and can help the fire modeling community to improve existing global emission inventories.

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14 Apr 2020 On the ice-nucleating potential of warm hydrometeors in

mixed-phase clouds

Michael Krayer, Agathe Chouippe, Markus Uhlmann, Jan Dušek, and

Thomas Leisner

Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-136,https://doi.org/10.5194/acp-2020-136,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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We address the phenomenon of ice enhancement in the vicinity of warm hydrometeors using highly-accurate flow simulation techniques. It is found that the transiently supersaturated zones induced by the hydrometeor's wake are by far larger than what has been previously estimated. The ice enhancement is quantified on the micro- and macroscale and its relevance is discussed. The provided results may contribute to a (currently unavailable) parametrization of the

phenomenon.

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14 Apr 2020 Mid-level clouds are frequent above the southeast Atlantic stratocumulus clouds Adeyemi A. Adebiyi, Paquita Zuidema, Ian Chang, and Sharon P. Burton Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-324,https://doi.org/10.5194/acp-2020-324,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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Over the southeast Atlantic, interactions between the low-level clouds and the overlying smoke aerosols have previously been highlighted, but no study has yet shown the presence of the mid-level clouds that complicates the aerosol–cloud interactions over the region. Here, we show that these super-cooled optically-thin mid-level clouds are relatively common, and they frequently occur at the top of the smoke layer between August–October, with significant radiative impacts on the low-level clouds.

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14 Apr 2020 Measurement report: Short-term variation of ammonia concentration in an urban area: contributions of mist evaporation and emissions from a forest canopy with bird droppings

Kazuo Osada

Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-244,https://doi.org/10.5194/acp-2020-244,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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Various sources and meteorological conditions affect the short-term variation of NH3 concentrations in the urban atmosphere. Analysis of 2 years of hourly data suggests that mist evaporation and stomata exchange of tree leaves after effects of bird droppings engender a rapid increase of NH3 concentrations. Emissions from urban tree canopies are a new mode of passing reactive nitrogen that has never been described as an important source in the literature.

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14 Apr 2020 Remote sensing of methane leakage from natural gas and petroleum systems revisited Oliver Schneising, Michael Buchwitz, Maximilian Reuter, Steffen Vanselow, Heinrich Bovensmann, and John P. Burrows Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-274,https://doi.org/10.5194/acp-2020-274,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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The switch from the use of coal to natural gas or oil for the energy generation potentially reduces the impact on global warming due to less CO2 emissions at the same energy content. However, this climate benefit is offset by fugitive methane emissions during the production and distribution process. We quantify the emissions and leakage rates relative to production for several large production regions based on satellite observations to evaluate the climate footprint of the gas

and oil industry.

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14 Apr 2020 The impact of ship emissions on air quality and human health in the Gothenburg area – Part II: Scenarios for 2040 Martin O. P. Ramacher, Lin Tang, Jana Moldanová, Volker Matthias, Matthias Karl, Erik Fridell, and Lasse Johansson Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-319,https://doi.org/10.5194/acp-2020-319,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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The effects of shipping emissions on air quality and health in the harbor city Gothenburg were simulated for different scenarios for the year 2040 with coupled regional and city-scale chemistry transport models, to evaluate the impact of regional emission regulations and on-shore electricity for ships at berth. The results show that contributions of shipping to exposure and associated health impacts from particulate matter and NO2 are significantly decreasing compared to 2012, in all scenarios.

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14 Apr 2020 Photooxidation of pinonaldehyde at ambient conditions investigated in the atmospheric simulation chamber SAPHIR Michael Rolletter, Marion Blocquet, Martin Kaminski, Birger Bohn, Hans-Peter Dorn, Andreas Hofzumahaus, Frank Holland, Xin Li, Franz Rohrer, Ralf Tillmann, Robert Wegener, Astrid Kiendler-Scharr, Andreas Wahner, and Hendrik Fuchs Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-310,https://doi.org/10.5194/acp-2020-310,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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The photooxidation of pinonaldehyde is investigated in a chamber study under natural sunlight and low NO conditions with and without an added hydroxyl radical (OH) scavenger. The experimentally determined pinonaldehyde photolysis frequency is faster by a factor of 3.5 than currently used parameterizations in atmospheric models. Yields of degradation products are measured in the presence and absence of OH. Measurements are compared to current atmospheric models and a theory-based mechanism.

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14 Apr 2020 The interaction between urbanization and aerosols during the typical haze event Miao Yu, Guiqian Tang, Yang Yang, Shiguang Miao, Yizhou Zhang, and

Qingchun Li

Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-303,https://doi.org/10.5194/acp-2020-303,

2020

Preprint under review for ACP (discussion: open, 1 comment) 14 Apr 2020 Using a global network of temperature lidars to identify temperature biases in the upper stratosphere in ECMWF reanalyses Graeme Marlton, Andrew Charlton-Perez, Giles Harrison, Inna Polichtchouk, Alain Hauchecorne, Philippe Keckhut, and Robin Wing Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-254,https://doi.org/10.5194/acp-2020-254,

2020

Preprint under review for ACP (discussion: open, 1 comment) Short

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A network of Rayleigh lidars have been used to infer the middle atmosphere temperature bias in ECMWF ERA-5 and ERA-interim reanalyses during 1990–2017. Results show that ERA-interim exhibits a cold bias of −3 to −4 K between 10 and 1 hPa. Comparisons with ERA-5 found a smaller bias of 1 K which varies between cold and warm between 10 and 3 hPa, indicating a good thermal representation of the atmosphere to 3 hPa. These biases must be accounted for in stratospheric studies using these reanalyses.

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14 Apr 2020 Non-target and suspect characterisation of organic contaminants in ambient air, Part I: Combining a novel sample clean-up method with comprehensive two-dimensional gas chromatography Laura Röhler, Pernilla Bohlin-Nizzetto, Pawel Rostkowski, Roland Kallenborn, and Martin Schlabach Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-263,https://doi.org/10.5194/acp-2020-263,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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A novel non-destructive, sulphuric acid free clean-up method of high-volume air samples was developed and evaluated with organic chemicals, covering a wide range of polarities (logP 2-11). This method, providing quantitative results of comparable quality to traditional methods, was combined with newly developed data treatment strategies for simultaneous suspect and non-target screening. The application on air samples from southern Norway revealed 90 new potential chemicals of emerging concern.

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14 Apr 2020 Optical properties of Central Asian aerosol relevant for spaceborne lidar applications and aerosol typing at 355 and 532 nm Julian Hofer, Albert Ansmann, Dietrich Althausen, Ronny Engelmann, Holger Baars, Ulla Wandinger, Sabur F. Abdullaev, and Abduvosit N.

Makhmudov

Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-258,https://doi.org/10.5194/acp-2020-258,

2020

Preprint under review for ACP (discussion: open, 1 comment) Short

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For the first time, a dense data set of particle extinction-to-backscatter ratios (lidar ratios), depolarization ratios, and backscatter- and extinction-related Ångström exponents for a Central Asian site are presented. The observations were performed with a continuously running multiwavelength polarization Raman lidar at Dushanbe, Tajikistan, during an 18-month campaign. The found optical properties reflect the large range of occurring aerosol

mixtures.

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14 Apr 2020 Laboratory studies of fresh and aged biomass burning aerosols emitted from east African biomass fuels – Part 2: Chemical properties and characterization Damon M. Smith, Tianqu Cui, Marc N. Fiddler, Rudra Pokhrel, Jason D. Surratt, and Solomon Bililign Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2019-1160,https://doi.org/10.5194/acp-2019-1160,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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There are many fuels used for domestic purposes in east Africa, producing a significant atmospheric burden of the resulting aerosols, which includes biomass burning particles. The chemical properties of these aerosols have not been investigated in the laboratory. In this work filter samples were collected from a smog chamber and methanol extracts from filters were analyzed to determine the light-absorption properties of biomass burning organic aerosol constituents.

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14 Apr 2020 Impact of biomass burning aerosols on radiation, clouds, and precipitation over the Amazon during the dry season: dependence of aerosol-cloud and aerosol-radiation interactions on aerosol loading Lixia Liu, Yafang Cheng, Siwen Wang, Chao Wei, Mira Pöhlker, Christopher Pöhlker, Paulo Artaxo, Manish Shrivastava, Meinrat O. Andreae, Ulrich Pöschl, and Hang Su Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-191,https://doi.org/10.5194/acp-2020-191,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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This modeling paper reveals how the aerosol-cloud interactions (ACI) and aerosol-radiation interactions (ARI) induced by biomass burning (BB) aerosols act oppositely on the radiation, cloud, and precipitation in Amazon during the dry season. The varying relative significance of the ACI and ARI with BB aerosol concentration leads to a nonlinear dependence of the total climate response on BB aerosol loading and features the growing importance of the ARI at high aerosol

loading.

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14 Apr 2020 Global-scale distribution of ozone in the remote troposphere from ATom and HIPPO airborne field missions Ilann Bourgeois, Jeffrey Peischl, Chelsea R. Thompson, Kenneth C. Aikin, Teresa Campos, Hannah Clark, Róisín Commane, Bruce Daube, Glenn W. Diskin, James W. Elkins, Ru-Shan Gao, Audrey Gaudel, Eric J. Hintsa, Bryan J. Johnson, Rigel Kivi, Kathryn McKain, Fred L. Moore, David D. Parrish, Richard Querel, Eric Ray, Ricardo Sánchez, Colm Sweeney, David W. Tarasick, Anne M. Thompson, Valérie Thouret, Jacquelyn C. Witte, Steve C. Wofsy, and Thomas B. Ryerson Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-315,https://doi.org/10.5194/acp-2020-315,

2020

Preprint under review for ACP (discussion: open, 0 comments) 09 Apr 2020 Technical note: Preparation and purification of atmospherically relevant _α_-hydroxynitrate esters of monoterpenes Elena Ali McKnight, Nicole P. Kretekos, Demi Owusu, and Rebecca Lyn

LaLonde

Atmos. Chem. Phys., 20, 4241–4254, https://doi.org/10.5194/acp-20-4241-2020,https://doi.org/10.5194/acp-20-4241-2020,

2020 Short summary

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This report describes a simple, safe and effective method to prepare nitrate esters of terpenes (carene, limonene, perillic alcohol, beta-pinene and alpha-pinene) which are key oxidation products in the atmosphere. These compounds are implicated in the formation of secondary organic aerosols. A compilation of the relevant spectroscopic data has been presented. The availability of these compounds and their characterization data will enable further study of the structure–reactivity relationships.

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09 Apr 2020 Oxygen and sulfur mass-independent isotopic signatures in black crusts: the complementary negative Δ33S reservoir of sulfate

aerosols?

Isabelle Genot, David Au Yang, Erwan Martin, Pierre Cartigny, Erwann Legendre, and Marc De Rafelis Atmos. Chem. Phys., 20, 4255–4273, https://doi.org/10.5194/acp-20-4255-2020,https://doi.org/10.5194/acp-20-4255-2020,

2020 Short summary

Short summary

Given their critical impact on radiative forcing, sulfate aerosols have been extensively studied using their isotope signatures (δ34S, ∆33S, ∆36S, δ18O, and ∆17O). A striking observation is that ∆33S > 0 ‰, implying a missing reservoir in the sulfur cycle. Here, we measured ∆33S < 0 ‰ in black crust sulfates (i.e., formed on carbonate walls) that must therefore result from distinct chemical pathway(s) compared to sulfate aerosols, and they may well represent this complementary reservoir.

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09 Apr 2020 Quantification and evaluation of atmospheric ammonia emissions with different methods: a case study for the Yangtze River

Delta region, China

Yu Zhao, Mengchen Yuan, Xin Huang, Feng Chen, and Jie Zhang Atmos. Chem. Phys., 20, 4275–4294, https://doi.org/10.5194/acp-20-4275-2020,https://doi.org/10.5194/acp-20-4275-2020,

2020 Short summary

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We estimated the ammonia emissions based on the constant emission factors and those characterizing the agricultural processes for the Yangtze River Delta, China. The discrepancies between the two estimates and their causes were analyzed. Based on ground and satellite observations, the two estimates were evaluated with air quality modeling. This work indicates ways to improve the emission estimation and helps better understand the necessity of multi-pollutant control strategy.

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09 Apr 2020 Influences of oceanic ozone deposition on tropospheric

photochemistry

Ryan J. Pound, Tomás Sherwen, Detlev Helmig, Lucy J. Carpenter, and

Mat J. Evans

Atmos. Chem. Phys., 20, 4227–4239, https://doi.org/10.5194/acp-20-4227-2020,https://doi.org/10.5194/acp-20-4227-2020,

2020 Short summary

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Ozone is an important pollutant with impacts on health and the environment. Ozone is lost to plants, land and the oceans. Loss to the ocean is slow compared to all other types of land cover and has not received as much attention. We build on previous work to more accurately model ozone loss to the ocean. We find changes in the concentration of ozone over the oceans, notably the Southern Ocean, which improves model performance.

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09 Apr 2020 Fossil fuel combustion, biomass burning and biogenic sources of fine carbonaceous aerosol in the Carpathian Basin Imre Salma, Anikó Vasanits-Zsigrai, Attila Machon, Tamás Varga, István Major, Virág Gergely, and Mihály Molnár Atmos. Chem. Phys., 20, 4295–4312, https://doi.org/10.5194/acp-20-4295-2020,https://doi.org/10.5194/acp-20-4295-2020,

2020 Short summary

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Major carbonaceous aerosol species were apportioned among FF combustion, BB and biogenic sources in various types of atmospheric environments of interest in the Carpathian Basin in different months representing different seasons. The conclusions present novel and valuable research contributions on a large area in central Europe.

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09 Apr 2020 A semi-empirical potential energy surface and line list for H216O extending into the near-ultraviolet Eamon K. Conway, Iouli E. Gordon, Jonathan Tennyson, Oleg L. Polyansky, Sergei N. Yurchenko, and Kelly Chance Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-286,https://doi.org/10.5194/acp-2020-286,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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Water vapor has a complex spectrum and absorbs from the microwave to the near UV where it dissociates. There is limited knowledge of the absorption features in the near UV and, of the available models and experiments, there is a large disagreement. We create a new ab initio model that is in good agreement with observation at 363 nm. At lower wavelengths, our calculations suggest the latest experiments over estimate absorption. This has implications on trace gas retrievals in

the near UV.

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09 Apr 2020 Airborne measurements and large-eddy simulations of small-scale Gravity Waves at the tropopause inversion layer over

Scandinavia

Sonja Gisinger, Johannes Wagner, and Benjamin Witschas Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-121,https://doi.org/10.5194/acp-2020-121,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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Gravity waves are an important coupling mechanism in the atmosphere. Measurements by two research aircraft during a mountain wave event over Scandinavia in 2016 revealed changes of the horizontal scales in the vertical velocity field and of momentum fluxes in the vicinity of the tropopause inversion. Idealized simulations revealed the presence of interfacial waves. They are found downstream of the mountain peaks meaning that they horizontally transport momentum/energy away from

their source.

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09 Apr 2020 A test of the ability of current bulk optical models to represent the radiative properties of cirrus cloud across the mid-and

far-infrared

Richard J. Bantges, Helen E. Brindley, Jonathan E. Murray, Alan E. Last, Cathryn Fox, Stuart Fox, Chawn Harlow, Sebastian J. O'Shea, Keith N. Bower, Bryan A. Baum, Ping Yang, and Juliet C. Pickering Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2019-1181,https://doi.org/10.5194/acp-2019-1181,

2020

Preprint under review for ACP (discussion: open, 1 comment) Short

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Understanding how ice clouds influence the Earth's energy balance remains a key challenge for predicting the future climate. These clouds are ubiquitous and are composed of ice crystals that have complex shapes which are incredibly difficult to model. This work exploits new measurements of the Earth's emitted thermal energy made from instruments flown on board an aircraft to test how well the latest ice cloud models can represent these clouds. Results indicate further developments are required.

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09 Apr 2020 Liquid–liquid phase separation in organic particles consisting of α-pinene and β-caryophyllene ozonolysis products and mixtures with commercially-available organic compounds Young-Chul Song, Ariana G. Bé, Scot T. Martin, Franz M. Geiger, Allan K. Bertram, Regan J. Thomson, and Mijung Song Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-318,https://doi.org/10.5194/acp-2020-318,

2020

Preprint under review for ACP (discussion: open, 1 comment) Short

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We report on LLPS of organic aerosol consisting of α-pinene- and β-caryophyllene-derived ozonolysis products and commercial organic compounds. Our results show that as compositional complexity increased from one to two organic species, LLPS occurred over a wider range of average O : C values of organic materials (increasing from 0.44 to 0.67). These results provide further evidence that LLPS is likely a frequent occurrence in OA particles in the troposphere, even in the absence of inorganic salt.

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08 Apr 2020 Influence of the dry aerosol particle size distribution and morphology on the cloud condensation nuclei activation. An experimental and theoretical investigation Junteng Wu, Alessandro Faccinetto, Symphorien Grimonprez, Sébastien Batut, Jérôme Yon, Pascale Desgroux, and Denis Petitprez Atmos. Chem. Phys., 20, 4209–4225, https://doi.org/10.5194/acp-20-4209-2020,https://doi.org/10.5194/acp-20-4209-2020,

2020 Short summary

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Soot particles released during anthropogenic activities may lead to positive direct or negative indirect climate forcing depending on their aging in the atmosphere. The latter occurs whenever soot particles act as cloud condensation nuclei (CCN) and trigger the formation of persistent clouds. Herein, we investigate the impact of the size distribution and morphology of freshly emitted soot particles on their aging process and propose a model to quantitatively predict their efficiency as CCN.

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08 Apr 2020 Shipborne measurements of Antarctic submicron organic aerosols: an NMR perspective linking multiple sources and bioregions Stefano Decesari, Marco Paglione, Matteo Rinaldi, Manuel Dall'Osto, Rafel Simó, Nicola Zanca, Francesca Volpi, Maria Cristina Facchini, Thorsten Hoffmann, Sven Götz, Christopher Johannes Kampf, Colin O'Dowd, Darius Ceburnis, Jurgita Ovadnevaite, and Emilio Tagliavini Atmos. Chem. Phys., 20, 4193–4207, https://doi.org/10.5194/acp-20-4193-2020,https://doi.org/10.5194/acp-20-4193-2020,

2020 Short summary

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Atmospheric aerosols in Antarctica contribute to regulate the delicate budget of cloud formation and precipitations. Besides the well-known biogenic production of sulfur-containing aerosol components such as methanesulfonate (MSA), the assessment of biological sources of organic particles in Antarctica remains an active area of research. Here we present the results of aerosol organic characterization during a research cruise performed in the Weddell Sea and in the Southern Ocean in Jan–Feb 2015.

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08 Apr 2020 Temporal Evolution of the Bromine Alpha Factor and Equivalent Effective Stratospheric Chlorine in Future Climate

Scenarios

J. Eric Klobas, Debra K. Weisenstein, Ross J. Salawitch, and David M.

Wilmouth

Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-276,https://doi.org/10.5194/acp-2020-276,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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The rates of important ozone-destroying chemical reactions in the stratosphere are likely to change in the future. We employ a computer model to evaluate how the rates of ozone destruction by chlorine and bromine may evolve in four climate change scenarios. We then show how these changing rates will impact a metric of the ozone-depleting power of the stratosphere known as Equivalent Effective Stratospheric Chlorine (EESC) and how projections of the date of ozone recovery using EESC are modified.

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08 Apr 2020 Improving NO2 and ozone simulations through global NO_x_

emission inversions

Zhen Qu, Daven K. Henze, Owen R. Cooper, and Jessica L. Neu Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-307,https://doi.org/10.5194/acp-2020-307,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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We use satellite observations and chemical transport modeling to quantify sources of NO_x_, a major air pollutant, over the past decade. We find improved simulations of the magnitude, seasonality and trends of NO2 and ozone concentrations using these derived emissions. Changes in ozone pollution driven by human and natural sources are identified in different regions. This work shows the benefits of remote sensing data and inverse modeling for more accurate ozone

simulations.

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08 Apr 2020 What have we missed when studying the impact of aerosols on surface ozone via changing photolysis rates? Jinhui Gao, Ying Li, Bin Zhu, Bo Hu, Lili Wang, and Fangwen Bao Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-140,https://doi.org/10.5194/acp-2020-140,

2020

Preprint under review for ACP (discussion: open, 1 comment) Short

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Light extinction of aerosols can decease surface ozone mainly via reducing photochemical production of ozone. However, it also leads high levels of ozone aloft being entrained down to the surface which partly counteracts the reduction in surface ozone. The impact of aerosols is more sensitive to local ozone, which suggests that while controlling the levels of aerosols, controlling the local ozone precursors is an effective way to suppress the increase of ozone over

China at present.

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07 Apr 2020 Supercooled liquid water cloud observed, analysed, and modelled at the top of the planetary boundary layer above Dome C,

Antarctica

Philippe Ricaud, Massimo Del Guasta, Eric Bazile, Niramson Azouz, Angelo Lupi, Pierre Durand, Jean-Luc Attié, Dana Veron, Vincent Guidard, and Paolo Grigioni Atmos. Chem. Phys., 20, 4167–4191, https://doi.org/10.5194/acp-20-4167-2020,https://doi.org/10.5194/acp-20-4167-2020,

2020 Short summary

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Thin (~ 100 m) supercooled liquid water (SLW, water staying in liquid phase below 0 °C) clouds have been detected, analysed, and modelled over the Dome C (Concordia, Antarctica) station during the austral summer 2018–2019 using observations and meteorological analyses. The SLW clouds were observed at the top of the planetary boundary layer and the SLW content was always strongly underestimated by the model indicating an incorrect simulation of the surface energy budget of the Antarctic Plateau.

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07 Apr 2020 Dehydration and low ozone in the tropopause layer over the Asian monsoon caused by tropical cyclones: Lagrangian transport calculations using ERA-Interim and ERA5 reanalysis data Dan Li, Bärbel Vogel, Rolf Müller, Jianchun Bian, Gebhard Günther, Felix Ploeger, Qian Li, Jinqiang Zhang, Zhixuan Bai, Holger Vömel,

and Martin Riese

Atmos. Chem. Phys., 20, 4133–4152, https://doi.org/10.5194/acp-20-4133-2020,https://doi.org/10.5194/acp-20-4133-2020,

2020 Short summary

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Low ozone and low water vapour signatures in the UTLS were investigated using balloon-borne measurements and trajectory calculations. The results show that deep convection in tropical cyclones over the western Pacific transports boundary air parcels with low ozone into the tropopause region. Subsequently, these air parcels are dehydrated when passing the lowest temperature region (< 190 K) during quasi-horizontal advection.

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07 Apr 2020 Formation mechanisms of atmospheric nitrate and sulfate during the winter haze pollution periods in Beijing: gas-phase, heterogeneous and aqueous-phase chemistry Pengfei Liu, Can Ye, Chaoyang Xue, Chenglong Zhang, Yujing Mu, and Xu

Sun

Atmos. Chem. Phys., 20, 4153–4165, https://doi.org/10.5194/acp-20-4153-2020,https://doi.org/10.5194/acp-20-4153-2020,

2020 Short summary

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A vast area in China is currently going through severe haze episodes with drastically elevated concentrations of PM2.5 in winter. Nitrate and sulfate are main constituents of PM2.5, but their formations via NO2 and SO2 oxidation are still not comprehensively understood. Our results found that the gas-phase reaction of NO2 with OH and the heterogeneous hydrolysis of N2O5 play key roles in nitrate formation, and SO2 aqueous-phase oxidation with H2O2 rather than NO2 contributed

greatly to sulfate.

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07 Apr 2020 Monitoring CO emissions of the metropolis Mexico City using TROPOMI CO observations Tobias Borsdorff, Agustín García Reynoso, Gilberto Maldonado, Bertha Mar-Morales, Wolfgang Stremme, Michel Grutter, and Jochen Landgraf Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-238,https://doi.org/10.5194/acp-2020-238,

2020

Preprint under review for ACP (discussion: open, 0 comments) 06 Apr 2020 Untangling causality in midlatitude aerosol–cloud

adjustments

Daniel T. McCoy, Paul Field, Hamish Gordon, Gregory S. Elsaesser, and

Daniel P. Grosvenor

Atmos. Chem. Phys., 20, 4085–4103, https://doi.org/10.5194/acp-20-4085-2020,https://doi.org/10.5194/acp-20-4085-2020,

2020 Short summary

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Incomplete understanding of how aerosol affects clouds degrades our ability to predict future climate. In particular, it is unclear how aerosol affects the lifetime of clouds. Does it increase or decrease it? This confusion is partially because causality flows from aerosol to clouds and clouds to aerosol, and it is hard to tell what is happening in observations. Here, we use simulations to tell us about how clouds affect aerosol and use this to interpret observations, showing increased lifetime.

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06 Apr 2020 Open cells exhibit weaker entrainment of free-tropospheric biomass burning aerosol into the south-east Atlantic

boundary layer

Steven J. Abel, Paul A. Barrett, Paquita Zuidema, Jianhao Zhang, Matt Christensen, Fanny Peers, Jonathan W. Taylor, Ian Crawford, Keith N. Bower, and Michael Flynn Atmos. Chem. Phys., 20, 4059–4084, https://doi.org/10.5194/acp-20-4059-2020,https://doi.org/10.5194/acp-20-4059-2020,

2020 Short summary

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In situ measurements of a free-tropospheric (FT) biomass burning aerosol plume in contact with the boundary layer inversion overriding a pocket of open cells (POC) and surrounding stratiform cloud are presented. The data highlight the contrasting thermodynamic, aerosol and cloud properties in the two cloud regimes and further demonstrate that the cloud regime plays a key role in regulating the flow of FT aerosols into the boundary layer, which has implications for the aerosol indirect effect.

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06 Apr 2020 Bromine from short-lived source gases in the extratropical northern hemispheric upper troposphere and lower

stratosphere (UTLS)

Timo Keber, Harald Bönisch, Carl Hartick, Marius Hauck, Fides Lefrancois, Florian Obersteiner, Akima Ringsdorf, Nils Schohl, Tanja Schuck, Ryan Hossaini, Phoebe Graf, Patrick Jöckel, and Andreas Engel Atmos. Chem. Phys., 20, 4105–4132, https://doi.org/10.5194/acp-20-4105-2020,https://doi.org/10.5194/acp-20-4105-2020,

2020 Short summary

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In this paper we summarize observations of short-lived halocarbons in the tropopause region. We show that, especially during winter, the levels of short-lived bromine gases at the extratropical tropopause are higher than at the tropical tropopause. We discuss the impact of the distributions on stratospheric bromine levels and compare our observations to two models with four different emission scenarios.

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06 Apr 2020 Dilution impacts on smoke aging: Evidence in BBOP data Anna L. Hodshire, Emily Ramnarine, Ali Akherati, Matthew L. Alvarado, Delphine K. Farmer, Shantanu H. Jathar, Sonia M. Kreidenweis, Chantelle R. Lonsdale, Timothy B. Onasch, Stephen R. Springston, Jian Wang, Yang Wang, Lawrence I. Kleinman, Arthur J. Sedlacek III, and

Jeffrey R. Pierce

Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-300,https://doi.org/10.5194/acp-2020-300,

2020

Preprint under review for ACP (discussion: open, 2 comments) Short

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Biomass burning emits particles and vapors that can impact both health and climate. Here, we investigate the role of dilution in the evolution of aerosol size and composition in observed US wildfire smoke plumes. Centers of plumes dilute more slowly than edges. We see differences in concentrations and composition between the centers and edges both in the first measurement and in subsequent measurements. Our findings support the hypothesis that plume dilution influences

smoke aging.

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06 Apr 2020 Discrepancies between MICS-Asia III Simulation and Observation for Surface Ozone in the Marine Atmosphere over the Northwestern Pacific Asian Rim Region Hajime Akimoto, Tatsuya Nagashima, Li Jie, Joshua S. Fu, and Zifa Wang Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-228,https://doi.org/10.5194/acp-2020-228,

2020

Preprint under review for ACP (discussion: open, 0 comments) 06 Apr 2020 Measurement report: Statistical modelling of long-term atmospheric inorganic gaseous species trends within proximity of the pollution hotspot in South Africa Jan-Stefan Swartz, Pieter G. Van Zyl, Johan P. Beukes, Corinne Galy-Lacaux, Avishkar Ramandh, and Jacobus J. Pienaar Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-166,https://doi.org/10.5194/acp-2020-166,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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Statistical modelling of interdependencies between local, regional and global parameters on long-term trends of atmospheric SO2, NO2 and O3 within the proximity of the pollution hotspot in South Africa, indicated that changes in meteorological conditions and/or variances in source influences contributed to temporal variability. The impact of increased anthropogenic activities and energy demand in this region was evident, while ENSO made a significant contribution to O3 levels.

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06 Apr 2020 Aerosol pH and chemical regimes of sulfate formation in aerosol water during winter haze in the North China Plain Wei Tao, Hang Su, Guangjie Zheng, Jiandong Wang, Chao Wei, Lixia Liu, Nan Ma, Meng Li, Qiang Zhang, Ulrich Pöschl, and Yafang Cheng Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-177,https://doi.org/10.5194/acp-2020-177,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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We simulated the thermodynamics and multiphase reactions in aerosol water during a wintertime haze event over the North China Plain. It was found that aerosol pH exhibited a strong spatio-temporal variability, and multiple oxidation pathways were predominant for particulate sulfate formation in different locations. Sensitivity tests further showed that ammonia, crustal particles and dissolved transition metal ions were important factors for multiphase chemistry during haze episodes.

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03 Apr 2020 Global sensitivity analysis of chemistry–climate model budgets of tropospheric ozone and OH: exploring model diversity Oliver Wild, Apostolos Voulgarakis, Fiona O'Connor, Jean-François Lamarque, Edmund M. Ryan, and Lindsay Lee Atmos. Chem. Phys., 20, 4047–4058, https://doi.org/10.5194/acp-20-4047-2020,https://doi.org/10.5194/acp-20-4047-2020,

2020 Short summary

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Global models of tropospheric chemistry and transport show a persistent diversity in results that has not been fully explained. We demonstrate the first use of global sensitivity analysis consistently across three independent models to explore these differences and reveal both clear similarities and surprising differences which have important implications for our assessment of future atmospheric

composition change.

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03 Apr 2020 Global dust cycle and uncertainty in CMIP5 models Chenglai Wu, Zhaohui Lin, and Xiaohong Liu Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-179,https://doi.org/10.5194/acp-2020-179,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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This study provides a comprehensive evaluation of global dust cycle in 15 models participating in the fifth phase of the Coupled Model Intercomparison Project (CMIP5). We assess the global budget and associated uncertainties. We also quantify the discrepancies in each model. The results highlight the large uncertainties in both the locations and intensities of dust emission. Our study will serve as a useful reference for model communities and help further model

improvements.

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03 Apr 2020 Towards the connection between snow microphysics and melting layer: Insights from multi-frequency and dual-polarization radar observations during BAECC Haoran Li, Jussi Tiira, Annakaisa von Lerber, and Dmitri Moisseev Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-16,https://doi.org/10.5194/acp-2020-16,

2020

Preprint under review for ACP (discussion: open, 0 comments) Short

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A method for classifying rimed and unrimed snow based on X- and Ka-band Doppler radar observations was developed to study the impact of precipitation intensity, aggregation, riming, and dendritic growth on melting layer properties. Multi-frequency and dual-polarization radar observations collected during BAECC 2014 show that radar characteristics of the melting layer strongly depend on precipitation intensity and show detectable differences between unrimed and rimed

snow.

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02 Apr 2020 Seasonal contrast in size distributions and mixing state of black carbon and its association with PM1.0 chemical composition from the eastern coast of India Sobhan Kumar Kompalli, Surendran Nair Suresh Babu, Sreedharan Krishnakumari Satheesh, Krishnaswamy Krishna Moorthy, Trupti Das, Ramasamy Boopathy, Dantong Liu, Eoghan Darbyshire, James D. Allan, James Brooks, Michael J. Flynn, and Hugh Coe Atmos. Chem. Phys., 20, 3965–3985, https://doi.org/10.5194/acp-20-3965-2020,https://doi.org/10.5194/acp-20-3965-2020,

2020

02 Apr 2020 Vertical profiles of submicron aerosol single scattering albedo over the Indian region immediately before monsoon onset and during its development: research from the SWAAMI field campaign Mohanan R. Manoj, Sreedharan K. Satheesh, Krishnaswamy K. Moorthy, and

Hugh Coe

Atmos. Chem. Phys., 20, 4031–4046, https://doi.org/10.5194/acp-20-4031-2020,https://doi.org/10.5194/acp-20-4031-2020,

2020 Short summary

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The study reports the observation of highly absorbing aerosol layers at high altitudes (1–2.5 km) prior to monsoon and during its development over the Indian region and quantifies its climate impacts. The absorption of solar radiation in these layers perturbs the onset of monsoon through the impact on the atmospheric stability. When height-resolved values of single scattering albedo (SSA) are used in a radiative transfer model, a maximum heating ~1 K d (~twice that using SSA) is obtained.

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02 Apr 2020 Using ship-borne observations of methane isotopic ratio in the Arctic Ocean to understand methane sources in the Arctic Antoine Berchet, Isabelle Pison, Patrick M. Crill, Brett Thornton, Philippe Bousquet, Thibaud Thonat, Thomas Hocking, Joël Thanwerdas, Jean-Daniel Paris, and Marielle Saunois Atmos. Chem. Phys., 20, 3987–3998, https://doi.org/10.5194/acp-20-3987-2020,https://doi.org/10.5194/acp-20-3987-2020,

2020 Short summary

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Methane isotopes in the atmosphere can help us differentiate between emission processes. A large variety of natural and anthropogenic emission types are active in the Arctic and are unsatisfactorily understood and documented up to now. A ship-based campaign was carried out in summer 2014, providing a unique dataset of isotopic measurements in the Arctic Ocean. Using a chemistry-transport model, we link these measurements to circumpolar emissions and retrieve information about their signature.

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02 Apr 2020 Heterogeneous formation of particulate nitrate under ammonium-rich regimes during the high-PM2.5 events in Nanjing, China Yu-Chi Lin, Yan-Lin Zhang, Mei-Yi Fan, and Mengying Bao Atmos. Chem. Phys., 20, 3999–4011, https://doi.org/10.5194/acp-20-3999-2020,https://doi.org/10.5194/acp-20-3999-2020,

2020 Short summary

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(1) Nitrate was a dominant contributing species in water-soluble inorganic ions during the high PM2.5 events in Nanjing. (2) Nitrate aerosols in Nanjing during the PM2.5 events were mainly produced by hydrolysis of N2O5 in preexisting aerosols under ammonium-rich regimes. (3) Control in NO_x_ emissions would inhibit production of nitrate aerosols since NH4NO3 formation was HNO3 limited in Nanjing.

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02 Apr 2020 The influence of typhoons on atmospheric composition deduced from IAGOS measurements over Taipei Frank Roux, Hannah Clark, Kuo-Ying Wang, Susanne Rohs, Bastien Sauvage, and Philippe Nédélec Atmos. Chem. Phys., 20, 3945–3963, https://doi.org/10.5194/acp-20-3945-2020,https://doi.org/10.5194/acp-20-3945-2020,

2020 Short summary

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Ozone, carbon monoxide and relative humidity were measured by two China Airlines aircraft equipped with IAGOS instruments during the summer of 2016. We examined landing and take-off profiles near Taipei (Taiwan), in the vicinity of three typhoons, in relation to ERA-5 meteorological reanalyses. Upstream of the storms, these data suggest that air is transported downwards from the stratosphere. Downstream, the troposphere is cleaner and moister due to the uplift of marine

boundary layer air.

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