Articles | Volume 26, issue 6
https://doi.org/10.5194/acp-26-4359-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/acp-26-4359-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
27 Mar 2026
Research article |
| 27 Mar 2026
| 27 Mar 2026
The lapse rate and the cold point tropopause in the Asian Summer Monsoon anticyclone
Institute of Climate and Energy Systems (ICE-4), Forschungszentrum Jülich, 52425 Jülich, Germany
Bärbel Vogel
Institute of Climate and Energy Systems (ICE-4), Forschungszentrum Jülich, 52425 Jülich, Germany
Martina Krämer
Institute of Climate and Energy Systems (ICE-4), Forschungszentrum Jülich, 52425 Jülich, Germany
Christian Rolf
Institute of Climate and Energy Systems (ICE-4), Forschungszentrum Jülich, 52425 Jülich, Germany
Nicole Spelten
Institute of Climate and Energy Systems (ICE-4), Forschungszentrum Jülich, 52425 Jülich, Germany
Fabrizio Ravegnani
National Research Council – Institute for Atmospheric Sciences and Climate (ISAC-CNR), 40129 Bologna, Italy
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Bärbel Vogel, Valentin Lauther, Franziska Köllner, Fatih Ekinci, Christian Rolf, Johannes Strobel, Ronja van Luijt, Michael C. Volk, Stephan Borrmann, Antonis Dragoneas, Oliver Eppers, Sergej Molleker, Peter Hoor, Linda Ort, Franziska Weyland, Andreas Zahn, Jan Clemens, Gebhard Günther, Oleh Kachula, Rolf Müller, Felix Ploeger, and Martin Riese
EGUsphere, https://doi.org/10.5194/egusphere-2025-5609, https://doi.org/10.5194/egusphere-2025-5609, 2025
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This work highlights the impact of the Asian summer monsoon on the chemical composition of the upper troposphere and lower stratosphere. Measurements of trace gases and aerosol particles uplifted by the Asian summer monsoon to higher altitudes are sparse. Here, we had the opportunity to use a whole suite of different measured trace gases and the chemical composition of aerosols, in combination with simulations, to better understand the complex transport and mixing processes in this region.
Oleh Kachula, Bärbel Vogel, Gebhard Günther, and Rolf Müller
Atmos. Chem. Phys., 25, 15171–15195, https://doi.org/10.5194/acp-25-15171-2025, https://doi.org/10.5194/acp-25-15171-2025, 2025
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We propose a novel method to define the boundary of the Asian summer monsoon anticyclone (ASMA) and provide the inter-annual and intra-seasonal analyses based on 44 years (1980–2023) and highlight individual years – 2017, 2022 and 2023 during which aircraft campaigns StratoClim, ACCLIP and PHILEAS took place respectively. Our method shows consistent results with previous studies but also provide new information about possible bimodality of the ASMA and inter-annual decrease of the ASMA area.
Rolf Müller, Lennart Bengtsson, John Birks, John Burrows, Ruprecht Jaenicke, and Richard S. Stolarski
Hist. Geo Space. Sci., 16, 31–40, https://doi.org/10.5194/hgss-16-31-2025, https://doi.org/10.5194/hgss-16-31-2025, 2025
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This paper reports a few anecdotes from the life of Paul J. Crutzen that were contributed by friends and colleagues. Taken together, these anecdotes should shed some light on the person that Paul was, as this is perhaps sometimes obscured when focusing solely on his many scientific achievements.
Shubhajyoti Roy, Satheesh P. R. Chandran, Suvarna Fadnavis, Vijay Sagar, Michaela I. Hegglin, and Rolf Müller
EGUsphere, https://doi.org/10.5194/egusphere-2025-1098, https://doi.org/10.5194/egusphere-2025-1098, 2025
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We show stratospheric ozone intrusions associated with sudden stratospheric warming events enhance ozone in the lower troposphere over the South Asia. The ozone enhancement increases ozone radiative forcing by 0.04±0.03 W.m-2 over South Asia. This increase in ozone radiative forcing potentially exacerbates regional climate warming.
Prashant Chavan, Suvarna Fadnavis, Anton Laakso, Jean-Paul Vernier, Simone Tilmes, and Rolf Müller
EGUsphere, https://doi.org/10.5194/egusphere-2024-3825, https://doi.org/10.5194/egusphere-2024-3825, 2025
Preprint archived
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Our simulations with volcanoes, when compared without volcanoes, show that volcanic aerosol precursors enter the tropical stratosphere, propagating upward and enhancing sulphate aerosol and heating. This stratospheric heating caused by the volcanoes reduces the amplitude of the QBO and disrupts its phases. Since QBO also modulates tropical convection and weather, we suggest including volcanic emissions and the QBO in the weather prediction model for a better forecast.
Yiran Zhang-Liu, Rolf Müller, Jens-Uwe Grooß, Sabine Robrecht, Bärbel Vogel, Abdul Mannan Zafar, and Ralph Lehmann
Atmos. Chem. Phys., 24, 12557–12574, https://doi.org/10.5194/acp-24-12557-2024, https://doi.org/10.5194/acp-24-12557-2024, 2024
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HCl null cycles in Antarctica are important for maintaining high values of ozone-destroying chlorine in Antarctic spring. These HCl null cycles are not affected by (1) using the most recent recommendations of chemical kinetics (compared to older recommendations), (2) accounting for dehydration in the Antarctic winter vortex, and (3) considering the observed (but unexplained) depletion of HCl in mid-winter in the Antarctic vortex throughout Antarctic winter.
Ling Zou, Reinhold Spang, Sabine Griessbach, Lars Hoffmann, Farahnaz Khosrawi, Rolf Müller, and Ines Tritscher
Atmos. Chem. Phys., 24, 11759–11774, https://doi.org/10.5194/acp-24-11759-2024, https://doi.org/10.5194/acp-24-11759-2024, 2024
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This study provided estimates of the occurrence of ice polar stratospheric clouds (PSCs) observed by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) and their connection with temperatures above the frost point (Tice) using a Lagrangian model derived from ERA5. We found that ice PSCs above Tice with temperature fluctuations along the backward trajectory are 33 % in the Arctic and 9 % in the Antarctic. This quantitative assessment enhances our understanding of ice PSCs.
Jayanarayanan Kuttippurath, Gopalakrishna Pillai Gopikrishnan, Rolf Müller, Sophie Godin-Beekmann, and Jerome Brioude
Atmos. Chem. Phys., 24, 6743–6756, https://doi.org/10.5194/acp-24-6743-2024, https://doi.org/10.5194/acp-24-6743-2024, 2024
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The current understanding and observational evidence do not provide any support for the possibility of an ozone hole occurring outside Antarctica today with respect to the present-day stratospheric halogen levels.
Felix Ploeger, Thomas Birner, Edward Charlesworth, Paul Konopka, and Rolf Müller
Atmos. Chem. Phys., 24, 2033–2043, https://doi.org/10.5194/acp-24-2033-2024, https://doi.org/10.5194/acp-24-2033-2024, 2024
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We present a novel mechanism of how regional anomalies in water vapour concentrations in the upper troposphere and lower stratosphere impact regional atmospheric circulation systems. These impacts include a displaced upper-level Asian monsoon circulation and strengthened prevailing westerlies in the Pacific region. Current climate models have biases in simulating these regional water vapour anomalies and circulation impacts, but the biases can be avoided by improving the model transport.
Reinhold Spang, Rolf Müller, and Alexandru Rap
Atmos. Chem. Phys., 24, 1213–1230, https://doi.org/10.5194/acp-24-1213-2024, https://doi.org/10.5194/acp-24-1213-2024, 2024
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Cirrus clouds play an important role in the radiation budget of the Earth. Despite recent progress in their observation, the radiative impact of ultra-thin cirrus clouds (UTC) in the tropopause region and in the lowermost stratosphere remains poorly constrained. Sensitivity model simulations with different ice parameters provide an uncertainty range for the radiative effect of UTCs. There is a need for better observed UTCs to enable the simulation of their potentially large effect on climate.
Jan Clemens, Bärbel Vogel, Lars Hoffmann, Sabine Griessbach, Nicole Thomas, Suvarna Fadnavis, Rolf Müller, Thomas Peter, and Felix Ploeger
Atmos. Chem. Phys., 24, 763–787, https://doi.org/10.5194/acp-24-763-2024, https://doi.org/10.5194/acp-24-763-2024, 2024
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The source regions of the Asian tropopause aerosol layer (ATAL) are debated. We use balloon-borne measurements of the layer above Nainital (India) in August 2016 and atmospheric transport models to find ATAL source regions. Most air originated from the Tibetan plateau. However, the measured ATAL was stronger when more air originated from the Indo-Gangetic Plain and weaker when more air originated from the Pacific. Hence, the results indicate important anthropogenic contributions to the ATAL.
Bärbel Vogel, C. Michael Volk, Johannes Wintel, Valentin Lauther, Jan Clemens, Jens-Uwe Grooß, Gebhard Günther, Lars Hoffmann, Johannes C. Laube, Rolf Müller, Felix Ploeger, and Fred Stroh
Atmos. Chem. Phys., 24, 317–343, https://doi.org/10.5194/acp-24-317-2024, https://doi.org/10.5194/acp-24-317-2024, 2024
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Over the Indian subcontinent, polluted air is rapidly uplifted to higher altitudes during the Asian monsoon season. We present an assessment of vertical transport in this region using different wind data provided by the European Centre for Medium-Range Weather Forecasts (ECMWF), as well as high-resolution aircraft measurements. In general, our findings confirm that the newest ECMWF reanalysis product, ERA5, yields a better representation of transport compared to the predecessor, ERA-Interim.
Rolf Müller, Ulrich Pöschl, Thomas Koop, Thomas Peter, and Ken Carslaw
Atmos. Chem. Phys., 23, 15445–15453, https://doi.org/10.5194/acp-23-15445-2023, https://doi.org/10.5194/acp-23-15445-2023, 2023
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Paul J. Crutzen was a pioneer in atmospheric sciences and a kind-hearted, humorous person with empathy for the private lives of his colleagues and students. He made fundamental scientific contributions to a wide range of scientific topics in all parts of the atmosphere. Paul was among the founders of the journal Atmospheric Chemistry and Physics. His work will continue to be a guide for generations of scientists and environmental policymakers to come.
Suvarna Fadnavis, Bernd Heinold, T. P. Sabin, Anne Kubin, Katty Huang, Alexandru Rap, and Rolf Müller
Atmos. Chem. Phys., 23, 10439–10449, https://doi.org/10.5194/acp-23-10439-2023, https://doi.org/10.5194/acp-23-10439-2023, 2023
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The influence of the COVID-19 lockdown on the Himalayas caused increases in snow cover and a decrease in runoff, ultimately leading to an enhanced snow water equivalent. Our findings highlight that, out of the two processes causing a retreat of Himalayan glaciers – (1) slow response to global climate change and (2) fast response to local air pollution – a policy action on the latter is more likely to be within the reach of possible policy action to help billions of people in southern Asia.
Liubov Poshyvailo-Strube, Rolf Müller, Stephan Fueglistaler, Michaela I. Hegglin, Johannes C. Laube, C. Michael Volk, and Felix Ploeger
Atmos. Chem. Phys., 22, 9895–9914, https://doi.org/10.5194/acp-22-9895-2022, https://doi.org/10.5194/acp-22-9895-2022, 2022
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Brewer–Dobson circulation (BDC) controls the composition of the stratosphere, which in turn affects radiation and climate. As the BDC cannot be measured directly, it is necessary to infer its strength and trends indirectly. In this study, we test in the
model worlddifferent methods for estimating the mean age of air trends based on a combination of stratospheric water vapour and methane data. We also provide simple practical advice of a more reliable estimation of the mean age of air trends.
Suvarna Fadnavis, Prashant Chavan, Akash Joshi, Sunil M. Sonbawne, Asutosh Acharya, Panuganti C. S. Devara, Alexandru Rap, Felix Ploeger, and Rolf Müller
Atmos. Chem. Phys., 22, 7179–7191, https://doi.org/10.5194/acp-22-7179-2022, https://doi.org/10.5194/acp-22-7179-2022, 2022
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We show that large amounts of anthropogenic aerosols are transported from South Asia to the northern Indian Ocean. These aerosols are then lifted into the UTLS by the ascending branch of the Hadley circulation. They are further transported to the Southern Hemisphere and downward via westerly ducts over the tropical Atlantic and Pacific. These aerosols increase tropospheric heating, resulting in an increase in water vapor, which is then transported to the UTLS.
Valentin Lauther, Bärbel Vogel, Johannes Wintel, Andrea Rau, Peter Hoor, Vera Bense, Rolf Müller, and C. Michael Volk
Atmos. Chem. Phys., 22, 2049–2077, https://doi.org/10.5194/acp-22-2049-2022, https://doi.org/10.5194/acp-22-2049-2022, 2022
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We show airborne in situ measurements of the very short-lived ozone-depleting substances CH2Cl2 and CHCl3, revealing particularly high concentrations of both species in the lower stratosphere. Back-trajectory calculations and 3D model simulations show that the air masses with high concentrations originated in the Asian boundary layer and were transported via the Asian summer monsoon. We also identify a fast transport pathway into the stratosphere via the North American monsoon and by hurricanes.
Dina Khordakova, Christian Rolf, Jens-Uwe Grooß, Rolf Müller, Paul Konopka, Andreas Wieser, Martina Krämer, and Martin Riese
Atmos. Chem. Phys., 22, 1059–1079, https://doi.org/10.5194/acp-22-1059-2022, https://doi.org/10.5194/acp-22-1059-2022, 2022
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Extreme storms transport humidity from the troposphere to the stratosphere. Here it has a strong impact on the climate. With ongoing global warming, we expect more storms and, hence, an enhancement of this effect. A case study was performed in order to measure the impact of the direct injection of water vapor into the lower stratosphere. The measurements displayed a significant transport of water vapor into the lower stratosphere, and this was supported by satellite and reanalysis data.
Prashant Chavan, Suvarna Fadnavis, Tanusri Chakroborty, Christopher E. Sioris, Sabine Griessbach, and Rolf Müller
Atmos. Chem. Phys., 21, 14371–14384, https://doi.org/10.5194/acp-21-14371-2021, https://doi.org/10.5194/acp-21-14371-2021, 2021
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Biomass burning (BB) over Asia is a strong source of carbonaceous aerosols during spring. Here, we show an outflow of Asian BB carbonaceous aerosols into the UTLS. These aerosols enhance atmospheric heating and produce circulation changes that lead to the enhancement of water vapor in the UTLS over the tropics. In the stratosphere, water vapor is further transported to the South Pole by the Brewer–Dobson circulation. Enhancement of water vapor in the UTLS has implications for climate change.
Jayanarayanan Kuttippurath, Wuhu Feng, Rolf Müller, Pankaj Kumar, Sarath Raj, Gopalakrishna Pillai Gopikrishnan, and Raina Roy
Atmos. Chem. Phys., 21, 14019–14037, https://doi.org/10.5194/acp-21-14019-2021, https://doi.org/10.5194/acp-21-14019-2021, 2021
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The Arctic winter/spring 2020 was one of the coldest with a strong and long-lasting vortex, high chlorine activation, severe denitrification, and unprecedented ozone loss. The loss was even equal to the levels of some of the warm Antarctic winters. Total column ozone values below 220 DU for several weeks and ozone loss saturation were observed during the period. These results show an unusual meteorology and warrant dedicated studies on the impact of climate change on ozone loss.
Fatih Ekinci, Oliver Eppers, Oliver Appel, Felix Ploeger, Antonis Dragoneas, Sergej Molleker, Philipp Brauner, Hans-Christoph Lachnitt, Franziska Weyland, Linda Ort, Nicolas Emig, Hans-Christian Clemen, Laura Tomsche, Martin Ebert, Peter Hoor, Bärbel Vogel, Yafang Cheng, Johannes Schneider, Stephan Borrmann, and Franziska Köllner
EGUsphere, https://doi.org/10.5194/egusphere-2026-998, https://doi.org/10.5194/egusphere-2026-998, 2026
This preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).
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This study shows that aerosol transported from the Asian summer monsoon region can substantially alter the background composition of the extratropical lower stratosphere. Aircraft-based measurements and model simulations reveal a strong increase of ammonium nitrate aerosol from summer to autumn 2023 caused by transport of young air masses from South and East Asia. These particles can persist for months and undergo chemical aging.
Jan Kaumanns, Jörn Ungermann, Bärbel Vogel, Sören Johansson, Erik Kretschmer, Felix Plöger, Peter Preuße, Wolfgang Woiwode, and Martin Riese
EGUsphere, https://doi.org/10.5194/egusphere-2026-650, https://doi.org/10.5194/egusphere-2026-650, 2026
This preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).
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During the PHILEAS aircraft campaign a self-matching experiment was conducted to study the mixing of Asian Summer monsoon air into the UTLS. We present the first 3-D tomographic observations of this mixing for multiple trace gas species. We use advanced clustering to identify the types of air and their transport pathways. Simulations of surface-origin tracers link several of these air types to different source regions. This study shows how pollutants of the monsoon enter the stratosphere.
Sylvia C. Sullivan, Aiko Voigt, Edgardo Sepúlveda Araya, Silvia Bucci, Annette Miltenberger, Meredith K. Kupinski, Christian Rolf, and Martina Krämer
Atmos. Chem. Phys., 26, 1685–1698, https://doi.org/10.5194/acp-26-1685-2026, https://doi.org/10.5194/acp-26-1685-2026, 2026
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We assess the temperature, moisture, and dynamics in the upper troposphere-lower stratosphere simulated over South Asia in a high-resolution model relative to aircraft data. The lower stratosphere tends to be too warm, too dry, and too quiescent in the model, and as a result, too few ice clouds are predicted to form there. These biases could affect radiative balance and circulation in other areas also, as significant upward transport of moisture and pollutants occurs during the Asian monsoon.
Irina Petropavlovskikh, Martine De Mazière, Anne M. Thompson, Jeannette D. Wild, James W. Hannigan, Henry B. Selkirk, Reem A. Hannum, Wolfgang Steinbrecht, Jean-Christopher Lambert, Roeland Van Malderen, Elizabeth Asher, Raul R. Cordero, Sophie Godin-Beekmann, Daan Hubert, Sergey Khaykin, Karin Kreher, Thierry Leblanc, Emmanuel Mahieu, Eliane Maillard Barras, Glen McConville, Gerald Nedoluha, Ivan Ortega, Alberto Redondas Marrero, Gunther Seckmeyer, Ryan M. Stauffer, Sarah A. Strode, Kim Strong, Takafumi Sugita, Michel Van Roozendael, Voltaire Velazco, Corinne Vigouroux, and Baerbel Vogel
EGUsphere, https://doi.org/10.5194/egusphere-2025-6557, https://doi.org/10.5194/egusphere-2025-6557, 2026
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This introduction to the special issue "Achievements and perspectives of the Network for the Detection of Atmospheric Composition Change after 35 years of operation” provides an overview of important research findings achieved under the NDACC objectives. The future of NDACC is discussed in the light of the evolution of the scientific questions, evolving collaborations with partners and Cooperating Networks, and the current landscape of gaps in satellite and ground-based observations.
Patrick Konjari, Christian Rolf, Martina Krämer, Armin Afchine, Nicole Spelten, Irene Bartolome Garcia, Annette Miltenberger, Nicolas Emig, Philipp Joppe, Johannes Schneider, Yun Li, Andreas Petzold, Heiko Bozem, and Peter Hoor
Atmos. Chem. Phys., 25, 18031–18050, https://doi.org/10.5194/acp-25-18031-2025, https://doi.org/10.5194/acp-25-18031-2025, 2025
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We investigated how a powerful storm over southern Sweden in June 2024 transported ice particles and moist air into the normally dry stratosphere. We observed unusually high water vapor and ice levels up to 1.5 kilometers above the tropopause. Although the extra water vapor lasted only a few days to weeks, it shows how such storms can temporarily alter the upper atmosphere’s composition.
Bärbel Vogel, Valentin Lauther, Franziska Köllner, Fatih Ekinci, Christian Rolf, Johannes Strobel, Ronja van Luijt, Michael C. Volk, Stephan Borrmann, Antonis Dragoneas, Oliver Eppers, Sergej Molleker, Peter Hoor, Linda Ort, Franziska Weyland, Andreas Zahn, Jan Clemens, Gebhard Günther, Oleh Kachula, Rolf Müller, Felix Ploeger, and Martin Riese
EGUsphere, https://doi.org/10.5194/egusphere-2025-5609, https://doi.org/10.5194/egusphere-2025-5609, 2025
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This work highlights the impact of the Asian summer monsoon on the chemical composition of the upper troposphere and lower stratosphere. Measurements of trace gases and aerosol particles uplifted by the Asian summer monsoon to higher altitudes are sparse. Here, we had the opportunity to use a whole suite of different measured trace gases and the chemical composition of aerosols, in combination with simulations, to better understand the complex transport and mixing processes in this region.
Heiko Bozem, Philipp Joppe, Yun Li, Nicolas Emig, Armin Afchine, Anna Breuninger, Joachim Curtius, Stefan Hofmann, Sadath Ismayil, Konrad Kandler, Daniel Kunkel, Arthur Kutschka, Hans-Christoph Lachnitt, Andreas Petzold, Sarah Richter, Timo Röschenthaler, Christian Rolf, Lisa Schneider, Johannes Schneider, Alexander Vogel, and Peter Hoor
Atmos. Meas. Tech., 18, 6545–6568, https://doi.org/10.5194/amt-18-6545-2025, https://doi.org/10.5194/amt-18-6545-2025, 2025
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Deployed on a Learjet as a tandem measurement platform during the TPEx I (TropoPause composition gradients and mixing Experiment) campaign in June 2024, the new TPC-TOSS (TropoPause Composition Towed Sensor Shuttle) system delivers high-resolution in situ data on ozone, aerosol, and key meteorological parameters. Laboratory and in-flight tests confirmed its precision and stability. Observed gradients near the tropopause reveal active mixing and transport processes in the tropopause region.
Philipp Joppe, Johannes Schneider, Jonas Wilsch, Heiko Bozem, Anna Breuninger, Joachim Curtius, Martin Ebert, Nicolas Emig, Peter Hoor, Sadath Ismayil, Konrad Kandler, Daniel Kunkel, Isabel Kurth, Hans-Christoph Lachnitt, Yun Li, Annette Miltenberger, Sarah Richter, Christian Rolf, Lisa Schneider, Cornelis Schwenk, Nicole Spelten, Alexander L. Vogel, Yafang Cheng, and Stephan Borrmann
Atmos. Chem. Phys., 25, 15077–15103, https://doi.org/10.5194/acp-25-15077-2025, https://doi.org/10.5194/acp-25-15077-2025, 2025
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We show measurements of a filament with biomass burning influence transported by a warm conveyor belt (WCB) into the tropopause region over Europe. The pollution originates from Canadian forest fires and is transported in the lower troposphere towards Europe. The WCB transport is followed by mixing with air masses of stratospheric chemical signatures. We hypothesize that this mixing leads to a change in the vertical gradient of the potential temperature.
Oleh Kachula, Bärbel Vogel, Gebhard Günther, and Rolf Müller
Atmos. Chem. Phys., 25, 15171–15195, https://doi.org/10.5194/acp-25-15171-2025, https://doi.org/10.5194/acp-25-15171-2025, 2025
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We propose a novel method to define the boundary of the Asian summer monsoon anticyclone (ASMA) and provide the inter-annual and intra-seasonal analyses based on 44 years (1980–2023) and highlight individual years – 2017, 2022 and 2023 during which aircraft campaigns StratoClim, ACCLIP and PHILEAS took place respectively. Our method shows consistent results with previous studies but also provide new information about possible bimodality of the ASMA and inter-annual decrease of the ASMA area.
Martina Krämer, Nicole Spelten, Christian Rolf, and Reinhold Spang
Atmos. Chem. Phys., 25, 13563–13583, https://doi.org/10.5194/acp-25-13563-2025, https://doi.org/10.5194/acp-25-13563-2025, 2025
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The size and number of cirrus ice crystals is one parameter influencing the still uncertain effect of cirrus clouds on climate. Here, the occurrence of ice particle sizes and concentrations with varying temperature and cloud microphysical thickness is analyzed as well as whether they formed in-situ or were transported upwards as frozen droplets from further below. The analyses are based on a large database of airborne measurements and extensive simulations.
Zhen Yang, Bärbel Vogel, Felix Plöger, Zhixuan Bai, Dan Li, Sabine Griessbach, Lars Hoffmann, Frank G. Wienhold, Elizabeth Asher, Alexandre A. Baron, Katie R. Smith, Troy Thornberry, Jianchun Bian, and Michaela I. Hegglin
EGUsphere, https://doi.org/10.5194/egusphere-2025-4842, https://doi.org/10.5194/egusphere-2025-4842, 2025
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Night-time balloon profiles over Lhasa, combined with satellite-constrained modeling, tracked the 2019 Raikoke volcano’s aerosol plumes through the Asian summer monsoon. We find two altitude-separated routes into the anticyclone. The monsoon partly blocks transport but permits entrainment and internal mixing, explaining gradual dilution. Matching the observations required stronger subgrid mixing, and the plume likely rose ~4–5 km from radiative heating.
Rolf Müller, Lennart Bengtsson, John Birks, John Burrows, Ruprecht Jaenicke, and Richard S. Stolarski
Hist. Geo Space. Sci., 16, 31–40, https://doi.org/10.5194/hgss-16-31-2025, https://doi.org/10.5194/hgss-16-31-2025, 2025
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This paper reports a few anecdotes from the life of Paul J. Crutzen that were contributed by friends and colleagues. Taken together, these anecdotes should shed some light on the person that Paul was, as this is perhaps sometimes obscured when focusing solely on his many scientific achievements.
Blaž Gasparini, Rachel Atlas, Aiko Voigt, Martina Krämer, and Peter N. Blossey
Atmos. Chem. Phys., 25, 9957–9979, https://doi.org/10.5194/acp-25-9957-2025, https://doi.org/10.5194/acp-25-9957-2025, 2025
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The evolution of tropical cirrus clouds is poorly understood, which contributes to large uncertainties in climate projections. To address this issue, we use novel tracers in a cloud-resolving model to track the life cycle of cirrus clouds. This approach provides insights into cloud formation, ice crystal evolution, and radiative effects of cirrus clouds. Additionally, we improve the model's cloud microphysics using a simple, computationally efficient approach that can be applied to other models.
Johannes C. Laube, Tanja J. Schuck, Sophie Baartman, Huilin Chen, Markus Geldenhuys, Steven van Heuven, Timo Keber, Maria Elena Popa, Elinor Tuffnell, Florian Voet, Bärbel Vogel, Thomas Wagenhäuser, Alessandro Zanchetta, and Andreas Engel
Atmos. Meas. Tech., 18, 4087–4102, https://doi.org/10.5194/amt-18-4087-2025, https://doi.org/10.5194/amt-18-4087-2025, 2025
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A large balloon was launched in summer 2021 in the Arctic to carry instruments for trace gas measurements up to 32 km, above the reach of aircraft. The main aims were to evaluate different techniques and atmospheric processes. We focus on halogenated greenhouse gases and ozone-depleting substances. For this, air was collected with the AirCore technique and a cryogenic air sampler and measured after the flight. A companion paper reports observations of major greenhouse gases.
Patrick Peter, Sigrun Matthes, Christine Frömming, Patrick Jöckel, Luca Bugliaro, Andreas Giez, Martina Krämer, and Volker Grewe
Atmos. Chem. Phys., 25, 5911–5934, https://doi.org/10.5194/acp-25-5911-2025, https://doi.org/10.5194/acp-25-5911-2025, 2025
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Our study examines how well the global climate model EMAC (ECHAM/MESSy Atmospheric Chemistry) predicts contrail formation by analysing temperature and humidity – two key factors for contrail development and persistence. The model underestimates temperature, leading to an overprediction of contrail formation and larger ice-supersaturated regions. Adjusting the model improves temperature accuracy but adds uncertainties. Better predictions of contrail formation areas can help optimise flight tracks to reduce aviation's climate effect.
Sreehari Kizhuveettil, Jordi Vila-Guerau de Arellano, Martina Krämer, Armin Afchine, Luiz A. T. Machado, Martin Zöger, and Wiebke Frey
EGUsphere, https://doi.org/10.5194/egusphere-2025-1637, https://doi.org/10.5194/egusphere-2025-1637, 2025
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Aircraft measurements are used to investigate high-altitude downdrafts in tropical deep convective clouds. The cloud water present in the downdrafts and its intensity do not show any correlation. Surprisingly, downdrafts occurred in supersaturated regions, contradicting the classical view of subsaturated downdrafts. Up- and downdrafts of similar strength show similar particle size distributions. These findings shed new light on the interplay between deep convection dynamics and microphysics.
Patrick Konjari, Christian Rolf, Michaela I. Hegglin, Susanne Rohs, Yun Li, Andreas Zahn, Harald Bönisch, Philippe Nedelec, Martina Krämer, and Andreas Petzold
Atmos. Chem. Phys., 25, 4269–4289, https://doi.org/10.5194/acp-25-4269-2025, https://doi.org/10.5194/acp-25-4269-2025, 2025
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This study introduces a new method to derive adjusted water vapor (H2O) climatologies for the upper tropopshere and lower statosphere (UT/LS) using data from 60 000 flights under the IAGOS program. Biases in the IAGOS water vapour dataset are adjusted, based on the more accurate IAGOS-CARIBIC data. The resulting highly resolved H2O climatologies will contribute to a better understanding of the H2O variability in the UT/LS and its connection to various transport and mixing processes.
Shubhajyoti Roy, Satheesh P. R. Chandran, Suvarna Fadnavis, Vijay Sagar, Michaela I. Hegglin, and Rolf Müller
EGUsphere, https://doi.org/10.5194/egusphere-2025-1098, https://doi.org/10.5194/egusphere-2025-1098, 2025
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We show stratospheric ozone intrusions associated with sudden stratospheric warming events enhance ozone in the lower troposphere over the South Asia. The ozone enhancement increases ozone radiative forcing by 0.04±0.03 W.m-2 over South Asia. This increase in ozone radiative forcing potentially exacerbates regional climate warming.
Prashant Chavan, Suvarna Fadnavis, Anton Laakso, Jean-Paul Vernier, Simone Tilmes, and Rolf Müller
EGUsphere, https://doi.org/10.5194/egusphere-2024-3825, https://doi.org/10.5194/egusphere-2024-3825, 2025
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Our simulations with volcanoes, when compared without volcanoes, show that volcanic aerosol precursors enter the tropical stratosphere, propagating upward and enhancing sulphate aerosol and heating. This stratospheric heating caused by the volcanoes reduces the amplitude of the QBO and disrupts its phases. Since QBO also modulates tropical convection and weather, we suggest including volcanic emissions and the QBO in the weather prediction model for a better forecast.
Yiran Zhang-Liu, Rolf Müller, Jens-Uwe Grooß, Sabine Robrecht, Bärbel Vogel, Abdul Mannan Zafar, and Ralph Lehmann
Atmos. Chem. Phys., 24, 12557–12574, https://doi.org/10.5194/acp-24-12557-2024, https://doi.org/10.5194/acp-24-12557-2024, 2024
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HCl null cycles in Antarctica are important for maintaining high values of ozone-destroying chlorine in Antarctic spring. These HCl null cycles are not affected by (1) using the most recent recommendations of chemical kinetics (compared to older recommendations), (2) accounting for dehydration in the Antarctic winter vortex, and (3) considering the observed (but unexplained) depletion of HCl in mid-winter in the Antarctic vortex throughout Antarctic winter.
Ling Zou, Reinhold Spang, Sabine Griessbach, Lars Hoffmann, Farahnaz Khosrawi, Rolf Müller, and Ines Tritscher
Atmos. Chem. Phys., 24, 11759–11774, https://doi.org/10.5194/acp-24-11759-2024, https://doi.org/10.5194/acp-24-11759-2024, 2024
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This study provided estimates of the occurrence of ice polar stratospheric clouds (PSCs) observed by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) and their connection with temperatures above the frost point (Tice) using a Lagrangian model derived from ERA5. We found that ice PSCs above Tice with temperature fluctuations along the backward trajectory are 33 % in the Arctic and 9 % in the Antarctic. This quantitative assessment enhances our understanding of ice PSCs.
Sandra Graßl, Christoph Ritter, Ines Tritscher, and Bärbel Vogel
Atmos. Chem. Phys., 24, 7535–7557, https://doi.org/10.5194/acp-24-7535-2024, https://doi.org/10.5194/acp-24-7535-2024, 2024
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Arctic lidar data for 1 year are compared with global modeling of aerosol tracers in the stratosphere. A trend in the aerosol backscatter can be found. These observations are further compared with a model study to investigate the aerosol origin of the observed arctic aerosol. We found a correlation with increased backscatter signal during summer and early autumn and pathways from the Southeast Asian monsoon region and remains of the Asian tropopause aerosol layer in the Arctic.
Jayanarayanan Kuttippurath, Gopalakrishna Pillai Gopikrishnan, Rolf Müller, Sophie Godin-Beekmann, and Jerome Brioude
Atmos. Chem. Phys., 24, 6743–6756, https://doi.org/10.5194/acp-24-6743-2024, https://doi.org/10.5194/acp-24-6743-2024, 2024
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The current understanding and observational evidence do not provide any support for the possibility of an ozone hole occurring outside Antarctica today with respect to the present-day stratospheric halogen levels.
Hengheng Zhang, Christian Rolf, Ralf Tillmann, Christian Wesolek, Frank Gunther Wienhold, Thomas Leisner, and Harald Saathoff
Aerosol Research, 2, 135–151, https://doi.org/10.5194/ar-2-135-2024, https://doi.org/10.5194/ar-2-135-2024, 2024
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Our study employs advanced tools, including scanning lidar, balloons, and UAVs, to explore aerosol particles in the atmosphere. The scanning lidar offers distinctive near-ground-level insights, enriching our comprehension of aerosol distribution from ground level to the free troposphere. This research provides valuable data for comparing remote sensing and in situ aerosol measurements, advancing our understanding of aerosol impacts on radiative transfer, clouds, and air quality.
Jan Clemens, Lars Hoffmann, Bärbel Vogel, Sabine Grießbach, and Nicole Thomas
Geosci. Model Dev., 17, 4467–4493, https://doi.org/10.5194/gmd-17-4467-2024, https://doi.org/10.5194/gmd-17-4467-2024, 2024
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Lagrangian transport models simulate the transport of air masses in the atmosphere. For example, one model (CLaMS) is well suited to calculating transport as it uses a special coordinate system and special vertical wind. However, it only runs inefficiently on modern supercomputers. Hence, we have implemented the benefits of CLaMS into a new model (MPTRAC), which is already highly efficient on modern supercomputers. Finally, in extensive tests, we showed that CLaMS and MPTRAC agree very well.
Martin Ebert, Ralf Weigel, Stephan Weinbruch, Lisa Schneider, Konrad Kandler, Stefan Lauterbach, Franziska Köllner, Felix Plöger, Gebhard Günther, Bärbel Vogel, and Stephan Borrmann
Atmos. Chem. Phys., 24, 4771–4788, https://doi.org/10.5194/acp-24-4771-2024, https://doi.org/10.5194/acp-24-4771-2024, 2024
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Particles were collected during the flight campaign StratoClim 2017 within the Asian tropopause aerosol layer (ATAL). Refractory particles from seven different flights were characterized by scanning and transmission electron microscopy (SEM, TEM). The most abundant refractory particles are silicates and non-volatile organics. The most important sources are combustion processes at the ground and the agitation of soil material. During one flight, small cinnabar particles (HgS) were also detected.
Ella Gilbert, Jhaswantsing Purseed, Yun Li, Martina Krämer, Beatrice Altamura, and Nicolas Bellouin
EGUsphere, https://doi.org/10.5194/egusphere-2024-821, https://doi.org/10.5194/egusphere-2024-821, 2024
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We use a simple experiment to explore the non-CO2 impacts of aviation on climate, which are considerably larger than the impact of the sector’s carbon emissions alone. We show that the main effect of our experiments – which intend to mimic the effect of aircraft soot emissions reaching existing high-altitude cirrus clouds – is to extend cloud lifetime, thereby enhancing their effect on climate.
Felix Ploeger, Thomas Birner, Edward Charlesworth, Paul Konopka, and Rolf Müller
Atmos. Chem. Phys., 24, 2033–2043, https://doi.org/10.5194/acp-24-2033-2024, https://doi.org/10.5194/acp-24-2033-2024, 2024
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We present a novel mechanism of how regional anomalies in water vapour concentrations in the upper troposphere and lower stratosphere impact regional atmospheric circulation systems. These impacts include a displaced upper-level Asian monsoon circulation and strengthened prevailing westerlies in the Pacific region. Current climate models have biases in simulating these regional water vapour anomalies and circulation impacts, but the biases can be avoided by improving the model transport.
Irene Bartolomé García, Odran Sourdeval, Reinhold Spang, and Martina Krämer
Atmos. Chem. Phys., 24, 1699–1716, https://doi.org/10.5194/acp-24-1699-2024, https://doi.org/10.5194/acp-24-1699-2024, 2024
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How many ice crystals of each size are in a cloud is a key parameter for the retrieval of cloud properties. The distribution of ice crystals is obtained from in situ measurements and used to create parameterizations that can be used when analyzing the remote-sensing data. Current parameterizations are based on data sets that do not include reliable measurements of small crystals, but in our study we use a data set that includes very small ice crystals to improve these parameterizations.
Reinhold Spang, Rolf Müller, and Alexandru Rap
Atmos. Chem. Phys., 24, 1213–1230, https://doi.org/10.5194/acp-24-1213-2024, https://doi.org/10.5194/acp-24-1213-2024, 2024
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Cirrus clouds play an important role in the radiation budget of the Earth. Despite recent progress in their observation, the radiative impact of ultra-thin cirrus clouds (UTC) in the tropopause region and in the lowermost stratosphere remains poorly constrained. Sensitivity model simulations with different ice parameters provide an uncertainty range for the radiative effect of UTCs. There is a need for better observed UTCs to enable the simulation of their potentially large effect on climate.
Jan Clemens, Bärbel Vogel, Lars Hoffmann, Sabine Griessbach, Nicole Thomas, Suvarna Fadnavis, Rolf Müller, Thomas Peter, and Felix Ploeger
Atmos. Chem. Phys., 24, 763–787, https://doi.org/10.5194/acp-24-763-2024, https://doi.org/10.5194/acp-24-763-2024, 2024
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The source regions of the Asian tropopause aerosol layer (ATAL) are debated. We use balloon-borne measurements of the layer above Nainital (India) in August 2016 and atmospheric transport models to find ATAL source regions. Most air originated from the Tibetan plateau. However, the measured ATAL was stronger when more air originated from the Indo-Gangetic Plain and weaker when more air originated from the Pacific. Hence, the results indicate important anthropogenic contributions to the ATAL.
Bärbel Vogel, C. Michael Volk, Johannes Wintel, Valentin Lauther, Jan Clemens, Jens-Uwe Grooß, Gebhard Günther, Lars Hoffmann, Johannes C. Laube, Rolf Müller, Felix Ploeger, and Fred Stroh
Atmos. Chem. Phys., 24, 317–343, https://doi.org/10.5194/acp-24-317-2024, https://doi.org/10.5194/acp-24-317-2024, 2024
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Over the Indian subcontinent, polluted air is rapidly uplifted to higher altitudes during the Asian monsoon season. We present an assessment of vertical transport in this region using different wind data provided by the European Centre for Medium-Range Weather Forecasts (ECMWF), as well as high-resolution aircraft measurements. In general, our findings confirm that the newest ECMWF reanalysis product, ERA5, yields a better representation of transport compared to the predecessor, ERA-Interim.
Rolf Müller, Ulrich Pöschl, Thomas Koop, Thomas Peter, and Ken Carslaw
Atmos. Chem. Phys., 23, 15445–15453, https://doi.org/10.5194/acp-23-15445-2023, https://doi.org/10.5194/acp-23-15445-2023, 2023
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Paul J. Crutzen was a pioneer in atmospheric sciences and a kind-hearted, humorous person with empathy for the private lives of his colleagues and students. He made fundamental scientific contributions to a wide range of scientific topics in all parts of the atmosphere. Paul was among the founders of the journal Atmospheric Chemistry and Physics. His work will continue to be a guide for generations of scientists and environmental policymakers to come.
Thomas Trickl, Martin Adelwart, Dina Khordakova, Ludwig Ries, Christian Rolf, Michael Sprenger, Wolfgang Steinbrecht, and Hannes Vogelmann
Atmos. Meas. Tech., 16, 5145–5165, https://doi.org/10.5194/amt-16-5145-2023, https://doi.org/10.5194/amt-16-5145-2023, 2023
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Tropospheric ozone have been measured for more than a century. Highly quantitative ozone measurements have been made at monitoring stations. However, deficits have been reported for vertical sounding systems. Here, we report a thorough intercomparison effort between a differential-absorption lidar system and two types of balloon-borne ozone sondes, also using ozone sensors at nearby mountain sites as references. The sondes agree very well with the lidar after offset corrections.
Francesco Cairo, Martina Krämer, Armin Afchine, Guido Di Donfrancesco, Luca Di Liberto, Sergey Khaykin, Lorenza Lucaferri, Valentin Mitev, Max Port, Christian Rolf, Marcel Snels, Nicole Spelten, Ralf Weigel, and Stephan Borrmann
Atmos. Meas. Tech., 16, 4899–4925, https://doi.org/10.5194/amt-16-4899-2023, https://doi.org/10.5194/amt-16-4899-2023, 2023
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Cirrus clouds have been observed over the Himalayan region between 10 km and the tropopause at 17–18 km. Data from backscattersonde, hygrometers, and particle cloud spectrometers have been compared to assess their consistency. Empirical relationships between optical parameters accessible with remote sensing lidars and cloud microphysical parameters (such as ice water content, particle number and surface area density, and particle aspherical fraction) have been established.
Elena De La Torre Castro, Tina Jurkat-Witschas, Armin Afchine, Volker Grewe, Valerian Hahn, Simon Kirschler, Martina Krämer, Johannes Lucke, Nicole Spelten, Heini Wernli, Martin Zöger, and Christiane Voigt
Atmos. Chem. Phys., 23, 13167–13189, https://doi.org/10.5194/acp-23-13167-2023, https://doi.org/10.5194/acp-23-13167-2023, 2023
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In this study, we show the differences in the microphysical properties between high-latitude (HL) cirrus and mid-latitude (ML) cirrus over the Arctic, North Atlantic, and central Europe during summer. The in situ measurements are combined with backward trajectories to investigate the influence of the region on cloud formation. We show that HL cirrus are characterized by a lower concentration of larger ice crystals when compared to ML cirrus.
Paul Konopka, Christian Rolf, Marc von Hobe, Sergey M. Khaykin, Benjamin Clouser, Elisabeth Moyer, Fabrizio Ravegnani, Francesco D'Amato, Silvia Viciani, Nicole Spelten, Armin Afchine, Martina Krämer, Fred Stroh, and Felix Ploeger
Atmos. Chem. Phys., 23, 12935–12947, https://doi.org/10.5194/acp-23-12935-2023, https://doi.org/10.5194/acp-23-12935-2023, 2023
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We studied water vapor in a critical region of the atmosphere, the Asian summer monsoon anticyclone, using rare in situ observations. Our study shows that extremely high water vapor values observed in the stratosphere within the Asian monsoon anticyclone still undergo significant freeze-drying and that water vapor concentrations set by the Lagrangian dry point are a better proxy for the stratospheric water vapor budget than rare observations of enhanced water mixing ratios.
Suvarna Fadnavis, Bernd Heinold, T. P. Sabin, Anne Kubin, Katty Huang, Alexandru Rap, and Rolf Müller
Atmos. Chem. Phys., 23, 10439–10449, https://doi.org/10.5194/acp-23-10439-2023, https://doi.org/10.5194/acp-23-10439-2023, 2023
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The influence of the COVID-19 lockdown on the Himalayas caused increases in snow cover and a decrease in runoff, ultimately leading to an enhanced snow water equivalent. Our findings highlight that, out of the two processes causing a retreat of Himalayan glaciers – (1) slow response to global climate change and (2) fast response to local air pollution – a policy action on the latter is more likely to be within the reach of possible policy action to help billions of people in southern Asia.
Silke Groß, Tina Jurkat-Witschas, Qiang Li, Martin Wirth, Benedikt Urbanek, Martina Krämer, Ralf Weigel, and Christiane Voigt
Atmos. Chem. Phys., 23, 8369–8381, https://doi.org/10.5194/acp-23-8369-2023, https://doi.org/10.5194/acp-23-8369-2023, 2023
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Aviation-emitted aerosol can have an impact on cirrus clouds. We present optical and microphysical properties of mid-latitude cirrus clouds which were formed under the influence of aviation-emitted aerosol or which were formed under rather pristine conditions. We find that cirrus clouds affected by aviation-emitted aerosol show larger values of the particle linear depolarization ratio, larger mean effective ice particle diameters and decreased ice particle number concentrations.
Lars Hoffmann, Paul Konopka, Jan Clemens, and Bärbel Vogel
Atmos. Chem. Phys., 23, 7589–7609, https://doi.org/10.5194/acp-23-7589-2023, https://doi.org/10.5194/acp-23-7589-2023, 2023
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Atmospheric convection plays a key role in tracer transport in the troposphere. Global meteorological forecasts and reanalyses typically have a coarse spatiotemporal resolution that does not adequately resolve the dynamics, transport, and mixing of air associated with storm systems or deep convection. We discuss the application of the extreme convection parameterization in a Lagrangian transport model to improve simulations of tracer transport from the boundary layer into the free troposphere.
Claudio Belotti, Flavio Barbara, Marco Barucci, Giovanni Bianchini, Francesco D'Amato, Samuele Del Bianco, Gianluca Di Natale, Marco Gai, Alessio Montori, Filippo Pratesi, Markus Rettinger, Christian Rolf, Ralf Sussmann, Thomas Trickl, Silvia Viciani, Hannes Vogelmann, and Luca Palchetti
Atmos. Meas. Tech., 16, 2511–2529, https://doi.org/10.5194/amt-16-2511-2023, https://doi.org/10.5194/amt-16-2511-2023, 2023
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FIRMOS (Far-Infrared Radiation Mobile Observation System) is a spectroradiometer measuring in the far-infrared, developed to support the preparation of the FORUM (Far-infrared Outgoing Radiation Understanding and Monitoring) satellite mission. In this paper, we describe the instrument, its data products, and the results of the comparison with a suite of observations made from a high-altitude site during a field campaign, in winter 2018–2019.
Georgios Dekoutsidis, Silke Groß, Martin Wirth, Martina Krämer, and Christian Rolf
Atmos. Chem. Phys., 23, 3103–3117, https://doi.org/10.5194/acp-23-3103-2023, https://doi.org/10.5194/acp-23-3103-2023, 2023
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Cirrus clouds affect Earth's atmosphere, deeming our study important. Here we use water vapor measurements by lidar and study the relative humidity (RHi) within and around midlatitude cirrus clouds. We find high supersaturations in the cloud-free air and within the clouds, especially near the cloud top. We study two cloud types with different formation processes. Finally, we conclude that the shape of the distribution of RHi can be used as an indicator of different cloud evolutionary stages.
Fayçal Lamraoui, Martina Krämer, Armin Afchine, Adam B. Sokol, Sergey Khaykin, Apoorva Pandey, and Zhiming Kuang
Atmos. Chem. Phys., 23, 2393–2419, https://doi.org/10.5194/acp-23-2393-2023, https://doi.org/10.5194/acp-23-2393-2023, 2023
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Cirrus in the tropical tropopause layer (TTL) can play a key role in vertical transport. We investigate the role of different cloud regimes and the associated ice habits in regulating the properties of the TTL. We use high-resolution numerical experiments at the scales of large-eddy simulations (LESs) and aircraft measurements. We found that LES-scale parameterizations that predict ice shape are crucial for an accurate representation of TTL cirrus and thus the associated (de)hydration process.
Yun Li, Christoph Mahnke, Susanne Rohs, Ulrich Bundke, Nicole Spelten, Georgios Dekoutsidis, Silke Groß, Christiane Voigt, Ulrich Schumann, Andreas Petzold, and Martina Krämer
Atmos. Chem. Phys., 23, 2251–2271, https://doi.org/10.5194/acp-23-2251-2023, https://doi.org/10.5194/acp-23-2251-2023, 2023
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The radiative effect of aviation-induced cirrus is closely related to ambient conditions and its microphysical properties. Our study investigated the occurrence of contrail and natural cirrus measured above central Europe in spring 2014. It finds that contrail cirrus appears frequently in the pressure range 200 to 245 hPa and occurs more often in slightly ice-subsaturated environments than expected. Avoiding slightly ice-subsaturated regions by aviation might help mitigate contrail cirrus.
Andreas Marsing, Ralf Meerkötter, Romy Heller, Stefan Kaufmann, Tina Jurkat-Witschas, Martina Krämer, Christian Rolf, and Christiane Voigt
Atmos. Chem. Phys., 23, 587–609, https://doi.org/10.5194/acp-23-587-2023, https://doi.org/10.5194/acp-23-587-2023, 2023
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We employ highly resolved aircraft measurements of profiles of the ice water content (IWC) in Arctic cirrus clouds in winter and spring, when solar irradiation is low. Using radiation transfer calculations, we assess the cloud radiative effect over different surfaces like snow or ocean. The variability in the IWC of the clouds affects their overall radiative effect and drives internal processes. This helps understand the role of cirrus in a rapidly changing Arctic environment.
Oliver Appel, Franziska Köllner, Antonis Dragoneas, Andreas Hünig, Sergej Molleker, Hans Schlager, Christoph Mahnke, Ralf Weigel, Max Port, Christiane Schulz, Frank Drewnick, Bärbel Vogel, Fred Stroh, and Stephan Borrmann
Atmos. Chem. Phys., 22, 13607–13630, https://doi.org/10.5194/acp-22-13607-2022, https://doi.org/10.5194/acp-22-13607-2022, 2022
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This paper clarifies the chemical composition of the Asian tropopause aerosol layer (ATAL) by means of airborne in situ aerosol mass spectrometry (AMS). Ammonium nitrate and organics are found to significantly contribute to the particle layer, while sulfate does not show a layered structure. An analysis of the single-particle mass spectra suggests that secondary particle formation and subsequent growth dominate the particle composition, rather than condensation on pre-existing primary particles.
Paul Konopka, Mengchu Tao, Marc von Hobe, Lars Hoffmann, Corinna Kloss, Fabrizio Ravegnani, C. Michael Volk, Valentin Lauther, Andreas Zahn, Peter Hoor, and Felix Ploeger
Geosci. Model Dev., 15, 7471–7487, https://doi.org/10.5194/gmd-15-7471-2022, https://doi.org/10.5194/gmd-15-7471-2022, 2022
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Pure trajectory-based transport models driven by meteorology derived from reanalysis products (ERA5) take into account only the resolved, advective part of transport. That means neither mixing processes nor unresolved subgrid-scale advective processes like convection are included. The Chemical Lagrangian Model of the Stratosphere (CLaMS) includes these processes. We show that isentropic mixing dominates unresolved transport. The second most important transport process is unresolved convection.
Clare E. Singer, Benjamin W. Clouser, Sergey M. Khaykin, Martina Krämer, Francesco Cairo, Thomas Peter, Alexey Lykov, Christian Rolf, Nicole Spelten, Armin Afchine, Simone Brunamonti, and Elisabeth J. Moyer
Atmos. Meas. Tech., 15, 4767–4783, https://doi.org/10.5194/amt-15-4767-2022, https://doi.org/10.5194/amt-15-4767-2022, 2022
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In situ measurements of water vapor in the upper troposphere are necessary to study cloud formation and hydration of the stratosphere but challenging due to cold–dry conditions. We compare measurements from three water vapor instruments from the StratoClim campaign in 2017. In clear sky (clouds), point-by-point differences were <1.5±8 % (<1±8 %). This excellent agreement allows detection of fine-scale structures required to understand the impact of convection on stratospheric water vapor.
Liubov Poshyvailo-Strube, Rolf Müller, Stephan Fueglistaler, Michaela I. Hegglin, Johannes C. Laube, C. Michael Volk, and Felix Ploeger
Atmos. Chem. Phys., 22, 9895–9914, https://doi.org/10.5194/acp-22-9895-2022, https://doi.org/10.5194/acp-22-9895-2022, 2022
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Brewer–Dobson circulation (BDC) controls the composition of the stratosphere, which in turn affects radiation and climate. As the BDC cannot be measured directly, it is necessary to infer its strength and trends indirectly. In this study, we test in the
model worlddifferent methods for estimating the mean age of air trends based on a combination of stratospheric water vapour and methane data. We also provide simple practical advice of a more reliable estimation of the mean age of air trends.
Suvarna Fadnavis, Prashant Chavan, Akash Joshi, Sunil M. Sonbawne, Asutosh Acharya, Panuganti C. S. Devara, Alexandru Rap, Felix Ploeger, and Rolf Müller
Atmos. Chem. Phys., 22, 7179–7191, https://doi.org/10.5194/acp-22-7179-2022, https://doi.org/10.5194/acp-22-7179-2022, 2022
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We show that large amounts of anthropogenic aerosols are transported from South Asia to the northern Indian Ocean. These aerosols are then lifted into the UTLS by the ascending branch of the Hadley circulation. They are further transported to the Southern Hemisphere and downward via westerly ducts over the tropical Atlantic and Pacific. These aerosols increase tropospheric heating, resulting in an increase in water vapor, which is then transported to the UTLS.
Andreas Wieser, Andreas Güntner, Peter Dietrich, Jan Handwerker, Dina Khordakova, Uta Ködel, Martin Kohler, Hannes Mollenhauer, Bernhard Mühr, Erik Nixdorf, Marvin Reich, Christian Rolf, Martin Schrön, Claudia Schütze, and Ute Weber
Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hess-2022-131, https://doi.org/10.5194/hess-2022-131, 2022
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We present an event-triggered observation concept which covers the entire process chain from heavy precipitation to flooding at the catchment scale. It combines flexible and mobile observing systems out of the fields of meteorology, hydrology and geophysics with stationary networks to capture atmospheric transport processes, heterogeneous precipitation patterns, land surface and subsurface storage processes, and runoff dynamics.
Mireia Papke Chica, Valerian Hahn, Tiziana Braeuer, Elena de la Torre Castro, Florian Ewald, Mathias Gergely, Simon Kirschler, Luca Bugliaro Goggia, Stefanie Knobloch, Martina Kraemer, Johannes Lucke, Johanna Mayer, Raphael Maerkl, Manuel Moser, Laura Tomsche, Tina Jurkat-Witschas, Martin Zoeger, Christian von Savigny, and Christiane Voigt
Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2022-255, https://doi.org/10.5194/acp-2022-255, 2022
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The mixed-phase temperature regime in convective clouds challenges our understanding of microphysical and radiative cloud properties. We provide a rare and unique dataset of aircraft in situ measurements in a strong mid-latitude convective system. We find that mechanisms initiating ice nucleation and growth strongly depend on temperature, relative humidity, and vertical velocity and variate within the measured system, resulting in altitude dependent changes of the cloud liquid and ice fraction.
Lars Hoffmann, Paul F. Baumeister, Zhongyin Cai, Jan Clemens, Sabine Griessbach, Gebhard Günther, Yi Heng, Mingzhao Liu, Kaveh Haghighi Mood, Olaf Stein, Nicole Thomas, Bärbel Vogel, Xue Wu, and Ling Zou
Geosci. Model Dev., 15, 2731–2762, https://doi.org/10.5194/gmd-15-2731-2022, https://doi.org/10.5194/gmd-15-2731-2022, 2022
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We describe the new version (2.2) of the Lagrangian transport model MPTRAC, which has been ported for application on GPUs. The model was verified by comparing kinematic trajectories and synthetic tracer simulations for the free troposphere and stratosphere from GPUs and CPUs. Benchmarking showed a speed-up of a factor of 16 of GPU-enabled simulations compared to CPU-only runs, indicating the great potential of applying GPUs for Lagrangian transport simulations on upcoming HPC systems.
Helmut Ziereis, Peter Hoor, Jens-Uwe Grooß, Andreas Zahn, Greta Stratmann, Paul Stock, Michael Lichtenstern, Jens Krause, Vera Bense, Armin Afchine, Christian Rolf, Wolfgang Woiwode, Marleen Braun, Jörn Ungermann, Andreas Marsing, Christiane Voigt, Andreas Engel, Björn-Martin Sinnhuber, and Hermann Oelhaf
Atmos. Chem. Phys., 22, 3631–3654, https://doi.org/10.5194/acp-22-3631-2022, https://doi.org/10.5194/acp-22-3631-2022, 2022
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Airborne observations were conducted in the lowermost Arctic stratosphere during the winter of 2015/2016. The observed distribution of reactive nitrogen shows clear indications of nitrification in mid-winter and denitrification in late winter. This was caused by the formation of polar stratospheric cloud particles, which were observed during several flights. The sedimentation and evaporation of these particles and the descent of air masses cause a redistribution of reactive nitrogen.
Sergey M. Khaykin, Elizabeth Moyer, Martina Krämer, Benjamin Clouser, Silvia Bucci, Bernard Legras, Alexey Lykov, Armin Afchine, Francesco Cairo, Ivan Formanyuk, Valentin Mitev, Renaud Matthey, Christian Rolf, Clare E. Singer, Nicole Spelten, Vasiliy Volkov, Vladimir Yushkov, and Fred Stroh
Atmos. Chem. Phys., 22, 3169–3189, https://doi.org/10.5194/acp-22-3169-2022, https://doi.org/10.5194/acp-22-3169-2022, 2022
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The Asian monsoon anticyclone is the key contributor to the global annual maximum in lower stratospheric water vapour. We investigate the impact of deep convection on the lower stratospheric water using a unique set of observations aboard the high-altitude M55-Geophysica aircraft deployed in Nepal in summer 2017 within the EU StratoClim project. We find that convective plumes of wet air can persist within the Asian anticyclone for weeks, thereby enhancing the occurrence of high-level clouds.
Valentin Lauther, Bärbel Vogel, Johannes Wintel, Andrea Rau, Peter Hoor, Vera Bense, Rolf Müller, and C. Michael Volk
Atmos. Chem. Phys., 22, 2049–2077, https://doi.org/10.5194/acp-22-2049-2022, https://doi.org/10.5194/acp-22-2049-2022, 2022
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We show airborne in situ measurements of the very short-lived ozone-depleting substances CH2Cl2 and CHCl3, revealing particularly high concentrations of both species in the lower stratosphere. Back-trajectory calculations and 3D model simulations show that the air masses with high concentrations originated in the Asian boundary layer and were transported via the Asian summer monsoon. We also identify a fast transport pathway into the stratosphere via the North American monsoon and by hurricanes.
Dina Khordakova, Christian Rolf, Jens-Uwe Grooß, Rolf Müller, Paul Konopka, Andreas Wieser, Martina Krämer, and Martin Riese
Atmos. Chem. Phys., 22, 1059–1079, https://doi.org/10.5194/acp-22-1059-2022, https://doi.org/10.5194/acp-22-1059-2022, 2022
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Extreme storms transport humidity from the troposphere to the stratosphere. Here it has a strong impact on the climate. With ongoing global warming, we expect more storms and, hence, an enhancement of this effect. A case study was performed in order to measure the impact of the direct injection of water vapor into the lower stratosphere. The measurements displayed a significant transport of water vapor into the lower stratosphere, and this was supported by satellite and reanalysis data.
Manuel Baumgartner, Christian Rolf, Jens-Uwe Grooß, Julia Schneider, Tobias Schorr, Ottmar Möhler, Peter Spichtinger, and Martina Krämer
Atmos. Chem. Phys., 22, 65–91, https://doi.org/10.5194/acp-22-65-2022, https://doi.org/10.5194/acp-22-65-2022, 2022
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An important mechanism for the appearance of ice particles in the upper troposphere at low temperatures is homogeneous nucleation. This process is commonly described by the
Koop line, predicting the humidity at freezing. However, laboratory measurements suggest that the freezing humidities are above the Koop line, motivating the present study to investigate the influence of different physical parameterizations on the homogeneous freezing with the help of a detailed numerical model.
Meike K. Rotermund, Vera Bense, Martyn P. Chipperfield, Andreas Engel, Jens-Uwe Grooß, Peter Hoor, Tilman Hüneke, Timo Keber, Flora Kluge, Benjamin Schreiner, Tanja Schuck, Bärbel Vogel, Andreas Zahn, and Klaus Pfeilsticker
Atmos. Chem. Phys., 21, 15375–15407, https://doi.org/10.5194/acp-21-15375-2021, https://doi.org/10.5194/acp-21-15375-2021, 2021
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Airborne total bromine (Brtot) and tracer measurements suggest Brtot-rich air masses persistently protruded into the lower stratosphere (LS), creating a high Brtot region over the North Atlantic in fall 2017. The main source is via isentropic transport by the Asian monsoon and to a lesser extent transport across the extratropical tropopause as quantified by a Lagrange model. The transport of Brtot via Central American hurricanes is also observed. Lastly, the impact of Brtot on LS O3 is assessed.
Christoph Mahnke, Ralf Weigel, Francesco Cairo, Jean-Paul Vernier, Armin Afchine, Martina Krämer, Valentin Mitev, Renaud Matthey, Silvia Viciani, Francesco D'Amato, Felix Ploeger, Terry Deshler, and Stephan Borrmann
Atmos. Chem. Phys., 21, 15259–15282, https://doi.org/10.5194/acp-21-15259-2021, https://doi.org/10.5194/acp-21-15259-2021, 2021
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In 2017, in situ aerosol measurements were conducted aboard the M55 Geophysica in the Asian monsoon region. The vertical particle mixing ratio profiles show a distinct layer (15–18.5 km), the Asian tropopause aerosol layer (ATAL). The backscatter ratio (BR) was calculated based on the aerosol size distributions and compared with the BRs detected by a backscatter probe and a lidar aboard M55, and by the CALIOP lidar. All four methods show enhanced BRs in the ATAL altitude range (max. at 17.5 km).
Julia Schneider, Kristina Höhler, Robert Wagner, Harald Saathoff, Martin Schnaiter, Tobias Schorr, Isabelle Steinke, Stefan Benz, Manuel Baumgartner, Christian Rolf, Martina Krämer, Thomas Leisner, and Ottmar Möhler
Atmos. Chem. Phys., 21, 14403–14425, https://doi.org/10.5194/acp-21-14403-2021, https://doi.org/10.5194/acp-21-14403-2021, 2021
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Homogeneous freezing is a relevant mechanism for the formation of cirrus clouds in the upper troposphere. Based on an extensive set of homogeneous freezing experiments at the AIDA chamber with aqueous sulfuric acid aerosol, we provide a new fit line for homogeneous freezing onset conditions of sulfuric acid aerosol focusing on cirrus temperatures. In the atmosphere, homogeneous freezing thresholds have important implications on the cirrus cloud occurrence and related cloud radiative effects.
Prashant Chavan, Suvarna Fadnavis, Tanusri Chakroborty, Christopher E. Sioris, Sabine Griessbach, and Rolf Müller
Atmos. Chem. Phys., 21, 14371–14384, https://doi.org/10.5194/acp-21-14371-2021, https://doi.org/10.5194/acp-21-14371-2021, 2021
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Biomass burning (BB) over Asia is a strong source of carbonaceous aerosols during spring. Here, we show an outflow of Asian BB carbonaceous aerosols into the UTLS. These aerosols enhance atmospheric heating and produce circulation changes that lead to the enhancement of water vapor in the UTLS over the tropics. In the stratosphere, water vapor is further transported to the South Pole by the Brewer–Dobson circulation. Enhancement of water vapor in the UTLS has implications for climate change.
Jayanarayanan Kuttippurath, Wuhu Feng, Rolf Müller, Pankaj Kumar, Sarath Raj, Gopalakrishna Pillai Gopikrishnan, and Raina Roy
Atmos. Chem. Phys., 21, 14019–14037, https://doi.org/10.5194/acp-21-14019-2021, https://doi.org/10.5194/acp-21-14019-2021, 2021
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The Arctic winter/spring 2020 was one of the coldest with a strong and long-lasting vortex, high chlorine activation, severe denitrification, and unprecedented ozone loss. The loss was even equal to the levels of some of the warm Antarctic winters. Total column ozone values below 220 DU for several weeks and ozone loss saturation were observed during the period. These results show an unusual meteorology and warrant dedicated studies on the impact of climate change on ozone loss.
Ralf Weigel, Christoph Mahnke, Manuel Baumgartner, Martina Krämer, Peter Spichtinger, Nicole Spelten, Armin Afchine, Christian Rolf, Silvia Viciani, Francesco D'Amato, Holger Tost, and Stephan Borrmann
Atmos. Chem. Phys., 21, 13455–13481, https://doi.org/10.5194/acp-21-13455-2021, https://doi.org/10.5194/acp-21-13455-2021, 2021
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In July and August 2017, the StratoClim mission took place in Nepal with eight flights of the M-55 Geophysica at up to 20 km in the Asian monsoon anticyclone. New particle formation (NPF) next to cloud ice was detected in situ by abundant nucleation-mode aerosols (> 6 nm) along with ice particles (> 3 µm). NPF was observed mainly below the tropopause, down to 15 % being non-volatile residues. Observed intra-cloud NPF indicates its importance for the composition in the tropical tropopause layer.
Luca Palchetti, Marco Barucci, Claudio Belotti, Giovanni Bianchini, Bertrand Cluzet, Francesco D'Amato, Samuele Del Bianco, Gianluca Di Natale, Marco Gai, Dina Khordakova, Alessio Montori, Hilke Oetjen, Markus Rettinger, Christian Rolf, Dirk Schuettemeyer, Ralf Sussmann, Silvia Viciani, Hannes Vogelmann, and Frank Gunther Wienhold
Earth Syst. Sci. Data, 13, 4303–4312, https://doi.org/10.5194/essd-13-4303-2021, https://doi.org/10.5194/essd-13-4303-2021, 2021
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The FIRMOS far-infrared (IR) prototype, developed for the preparation of the ESA FORUM mission, was deployed for the first time at Mt. Zugspitze at 3000 m altitude to measure the far-IR spectrum of atmospheric emissions. The measurements, including co-located radiometers, lidars, radio soundings, weather, and surface properties, provide a unique dataset to study radiative properties of water vapour, cirrus clouds, and snow emissivity over the IR emissions, including the under-explored far-IR.
Ralf Weigel, Christoph Mahnke, Manuel Baumgartner, Antonis Dragoneas, Bärbel Vogel, Felix Ploeger, Silvia Viciani, Francesco D'Amato, Silvia Bucci, Bernard Legras, Beiping Luo, and Stephan Borrmann
Atmos. Chem. Phys., 21, 11689–11722, https://doi.org/10.5194/acp-21-11689-2021, https://doi.org/10.5194/acp-21-11689-2021, 2021
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In July and August 2017, eight StratoClim mission flights of the Geophysica reached up to 20 km in the Asian monsoon anticyclone. New particle formation (NPF) was identified in situ by abundant nucleation-mode aerosols (6–15 nm in diameter) with mixing ratios of up to 50 000 mg−1. NPF occurred most frequently at 12–16 km with fractions of non-volatile residues of down to 15 %. Abundance and productivity of observed NPF indicate its ability to promote the Asian tropopause aerosol layer.
Lukas Krasauskas, Jörn Ungermann, Peter Preusse, Felix Friedl-Vallon, Andreas Zahn, Helmut Ziereis, Christian Rolf, Felix Plöger, Paul Konopka, Bärbel Vogel, and Martin Riese
Atmos. Chem. Phys., 21, 10249–10272, https://doi.org/10.5194/acp-21-10249-2021, https://doi.org/10.5194/acp-21-10249-2021, 2021
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A Rossby wave (RW) breaking event was observed over the North Atlantic during the WISE measurement campaign in October 2017. Infrared limb sounding measurements of trace gases in the lower stratosphere, including high-resolution 3-D tomographic reconstruction, revealed complex spatial structures in stratospheric tracers near the polar jet related to previous RW breaking events. Backward-trajectory analysis and tracer correlations were used to study mixing and stratosphere–troposphere exchange.
Gerald Wetzel, Felix Friedl-Vallon, Norbert Glatthor, Jens-Uwe Grooß, Thomas Gulde, Michael Höpfner, Sören Johansson, Farahnaz Khosrawi, Oliver Kirner, Anne Kleinert, Erik Kretschmer, Guido Maucher, Hans Nordmeyer, Hermann Oelhaf, Johannes Orphal, Christof Piesch, Björn-Martin Sinnhuber, Jörn Ungermann, and Bärbel Vogel
Atmos. Chem. Phys., 21, 8213–8232, https://doi.org/10.5194/acp-21-8213-2021, https://doi.org/10.5194/acp-21-8213-2021, 2021
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Measurements of the pollutants C2H6, C2H2, HCOOH, and PAN were performed in the North Atlantic UTLS region with the airborne limb imager GLORIA in 2017. Enhanced amounts of these species were detected in the upper troposphere and even in the lowermost stratosphere (PAN). Main sources of these gases are forest fires in North America and anthropogenic pollution in South Asia. Simulations of EMAC and CAMS are qualitatively able to reproduce the measured data but underestimate the absolute amounts.
Irene Bartolome Garcia, Reinhold Spang, Jörn Ungermann, Sabine Griessbach, Martina Krämer, Michael Höpfner, and Martin Riese
Atmos. Meas. Tech., 14, 3153–3168, https://doi.org/10.5194/amt-14-3153-2021, https://doi.org/10.5194/amt-14-3153-2021, 2021
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Cirrus clouds contribute to the general radiation budget of the Earth. Measuring optically thin clouds is challenging but the IR limb sounder GLORIA possesses the necessary technical characteristics to make it possible. This study analyses data from the WISE campaign obtained with GLORIA. We developed a cloud detection method and derived characteristics of the observed cirrus-like cloud top, cloud bottom or position with respect to the tropopause.
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Short summary
In the Asian summer monsoon anticyclone the lapse rate tropopause, and not the cold point, constitutes a good estimate of the upper boundary of the well mixed tropospheric air mass. For strong convection there is substantial dehydration at the cold point tropopause (in summer 2017). Above the cold point tropopause, under such conditions, neither ice particle occurrence, nor enhanced molar mixing ratios of water vapour (above ≲ 6 ppm) are observed.
In the Asian summer monsoon anticyclone the lapse rate tropopause, and not the cold point,...
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