Articles | Volume 21, issue 21
https://doi.org/10.5194/acp-21-16319-2021
© Author(s) 2021. 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-21-16319-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
08 Nov 2021
Research article |
| 08 Nov 2021
| 08 Nov 2021
Disentangling different moisture transport pathways over the eastern subtropical North Atlantic using multi-platform isotope observations and high-resolution numerical modelling
Fabienne Dahinden
CORRESPONDING AUTHOR
Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland
Franziska Aemisegger
Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland
Heini Wernli
Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland
Matthias Schneider
Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, Karlsruhe, Germany
Christopher J. Diekmann
Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, Karlsruhe, Germany
Benjamin Ertl
Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, Karlsruhe, Germany
Peter Knippertz
Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, Karlsruhe, Germany
Martin Werner
Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
Stephan Pfahl
Institute for Meteorology, Freie Universität Berlin, Berlin, Germany
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Tuule Müürsepp, Michael Sprenger, Heini Wernli, and Hanna Joos
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Kanwal Shahzadi, Matthias Schneider, Nga Ying Lo, Frank Hase, Jörg Meyer, Ugur Cayoglu, Tobias Borsdorff, and Mari C. Martinez-Velarte
Earth Syst. Sci. Data, 18, 2153–2177, https://doi.org/10.5194/essd-18-2153-2026, https://doi.org/10.5194/essd-18-2153-2026, 2026
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We merge TROPOMI and IASI L2 methane data from January 2018 to June 2021 on a global scale. The data merging yields total column-averaged and upper tropospheric/stratospheric partial column-averaged mole fractions (already provided by the individual data sets). In addition, it outputs tropospheric partial column-averaged mole fractions (not provided by any of the two individual data sets). We briefly document their increased potential for quantifying near-surface methane emissions.
Donghe Zhu, Patrick Pieper, Stephan Pfahl, and Erich Fischer
EGUsphere, https://doi.org/10.5194/egusphere-2026-1258, https://doi.org/10.5194/egusphere-2026-1258, 2026
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Titouan Tcheng, Elise Fourré, Christophe Leroy-Dos Santos, Frédéric Parrenin, Emmanuel Le Meur, Frédéric Prié, Olivier Jossoud, Roxanne Jacob, Bénédicte Minster, Olivier Magand, Cécile Agosta, Niels Dutrievoz, Vincent Favier, Léa Baubant, Coralie Lassalle-Bernard, Mathieu Casado, Martin Werner, Alexandre Cauquoin, Laurent Arnaud, Bruno Jourdain, Ghislain Picard, Marie Bouchet, and Amaëlle Landais
The Cryosphere, 20, 1599–1618, https://doi.org/10.5194/tc-20-1599-2026, https://doi.org/10.5194/tc-20-1599-2026, 2026
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Maurus Borne, Peter Knippertz, Michael Rennie, and Martin Weissmann
Weather Clim. Dynam., 7, 489–505, https://doi.org/10.5194/wcd-7-489-2026, https://doi.org/10.5194/wcd-7-489-2026, 2026
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This study shows that Aeolus satellite wind lidar observations significantly improve wind forecasts and that these improvements lead to more accurate rainfall predictions, particularly at longer lead times and during winter seasons in the extratropics. The benefits are likely due to better representation of large-scale atmospheric features such as jet streams and Rossby waves, highlighting Aeolus's value for numerical weather prediction.
Jan Nitzbon, Moritz Langer, Luca Alexander Müller-Ißberner, Elisabeth Dietze, and Martin Werner
Clim. Past, 22, 377–403, https://doi.org/10.5194/cp-22-377-2026, https://doi.org/10.5194/cp-22-377-2026, 2026
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Using model simulations, we show that the larger temperature seasonality of the mid Holocene and the last interglacial climates led to marked surficial permafrost thaw during warm summers, while cold winters allowed for permafrost persistence at depth. We argue that past interglacial climates have limited suitability as analogues for future permafrost dynamics, for which we anticipate a trajectory of unprecedented thaw magnitude since at least MIS (Marine Isotope Stage) 11c.
Thibaut Caley, Niclas Rieger, Martin Werner, Claire Waelbroeck, Héloise Barathieu, Tamara Happé, and Didier M. Roche
Clim. Past, 22, 247–263, https://doi.org/10.5194/cp-22-247-2026, https://doi.org/10.5194/cp-22-247-2026, 2026
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Density of seawater is a critical property that controls ocean dynamics. We developed the use of the δ18Oc of planktonic foraminifera as a surface paleodensity proxy for the ocean using Bayesian regression models calibrated to mean annual surface density. We reconstructed annual surface density during the last glacial maximum and late Holocene time periods. These results will be used to evaluate numerical climate models in their ability to simulate past ocean surface density.
Nora Zilibotti, Heini Wernli, and Sebastian Schemm
Weather Clim. Dynam., 7, 201–221, https://doi.org/10.5194/wcd-7-201-2026, https://doi.org/10.5194/wcd-7-201-2026, 2026
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This study investigates the relationship between jet strength and storm track activity in the North Pacific and North Atlantic with a new approach that does not rely on monthly averaging. We find a consistent behaviour in the two basins, with two distinct relationships on seasonal and sub-monthly timescales emerging. This work underlines the importance of separating different timescales of variability to understand the interplay of jet characteristics and storm track activity.
Georgina Falster, Gab Abramowitz, Sanaa Hobeichi, Catherine Hughes, Pauline Treble, Nerilie J. Abram, Michael I. Bird, Alexandre Cauquoin, Bronwyn Dixon, Russell Drysdale, Chenhui Jin, Niels Munksgaard, Bernadette Proemse, Jonathan J. Tyler, Martin Werner, and Carol V. Tadros
Hydrol. Earth Syst. Sci., 30, 289–315, https://doi.org/10.5194/hess-30-289-2026, https://doi.org/10.5194/hess-30-289-2026, 2026
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We used a random forest approach to produce estimates of monthly precipitation stable isotope variability from 1962–2023, at high resolution across the entire Australian continent. Comprehensive skill and sensitivity testing shows that our random forest models skilfully predict precipitation isotope values in places and times that observations are not available. We make all outputs freely available, facilitating use in fields from ecology and hydrology to archaeology and forensic science.
Katharina Hartmuth, Dominik Büeler, and Heini Wernli
Weather Clim. Dynam., 7, 129–148, https://doi.org/10.5194/wcd-7-129-2026, https://doi.org/10.5194/wcd-7-129-2026, 2026
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This study presents three case studies of applying a newly developed method to quantify the uncertainty of the operational ensemble from the European Centre for Medium-Range Weather Forecasts in forecasting precipitation and wind extremes associated with Mediterranean cyclones. We find that the cyclones as well as their associated extremes are predicted well for lead times ≤ 48 h; however, for longer lead times there is large case-to-case variability in the ensemble performance.
Hannah Meyer, Konrad Kandler, Sylvain Dupont, Jerónimo Escribano, Jessica Girdwood, George Nikolich, Andrés Alastuey, Vicken Etyemezian, Cristina González-Flórez, Adolfo González-Romero, Tareq Hussein, Mark Irvine, Peter Knippertz, Ottmar Möhler, Xavier Querol, Chris Stopford, Franziska Vogel, Frederik Weis, Andreas Wieser, Carlos Pérez García-Pando, and Martina Klose
Atmos. Meas. Tech., 19, 21–61, https://doi.org/10.5194/amt-19-21-2026, https://doi.org/10.5194/amt-19-21-2026, 2026
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Mineral dust particles emitted from dry soils are of various sizes, yet the abundance of very large particles is not well understood. Here we measured the dust size distribution from fine to giant particles at an emission source during a field campaign in Jordan (J-WADI) using multiple instruments. Our findings show that large particles make up a significant part of the total dust mass. This knowledge is essential to improve climate models and to predict dust impacts on climate and environment.
Lina Lucas, Christian Barthlott, Corinna Hoose, and Peter Knippertz
Atmos. Chem. Phys., 25, 18527–18548, https://doi.org/10.5194/acp-25-18527-2025, https://doi.org/10.5194/acp-25-18527-2025, 2025
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We studied how climate change and cleaner air could affect severe storms in Germany. Using high-resolution weather simulations of past supercell storms under warmer and less polluted conditions, we found that storms may become more intense, with heavier rainfall and larger hailstones. These changes suggest an increased risk of damage in the future. Our findings help improve understanding of how extreme storms may evolve in a changing climate.
Qiansi Tu, Frank Hase, Ying Zhang, Jiaxin Fang, Yanwu Jiang, Xiaofan Li, Matthias Schneider, Zhuolin Yang, Xin Zhang, and Zhengqiang Li
Atmos. Chem. Phys., 25, 17779–17796, https://doi.org/10.5194/acp-25-17779-2025, https://doi.org/10.5194/acp-25-17779-2025, 2025
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Understanding greenhouse gas and air pollutant concentrations and emissions characteristics in the Qinghai-Tibetan Plateau cities remains limited. We present the first CO2, CH4 and CO abundances using a portal Fourier-transform infrared (FTIR) spectrometer in Xining. Ground-based data exceeded satellite/model estimates, indicating higher local emissions. Strong CO discrepancies and ∆XCO–∆XCO2 correlation under easterly winds highlight the value of portable FTIR for urban emission studies.
Franziska Schnyder, Ming Hon Franco Lee, and Heini Wernli
Weather Clim. Dynam., 6, 1319–1337, https://doi.org/10.5194/wcd-6-1319-2025, https://doi.org/10.5194/wcd-6-1319-2025, 2025
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In this study, we investigate a particularly long-lived example of a Siberian summer cyclone, which originates during a heat wave in Kazakhstan in July 2021 and propagates into the Arctic, where it leads to heavy precipitation and alters the Arctic tropopause. Although a rare event in current climate, this case reveals how compounding events may be linked by one weather system and portrays a type of cyclone event which is likely to become more frequent in a warmer climate.
Alison J. McLaren, Louise C. Sime, Simon Wilson, Jeff Ridley, Qinggang Gao, Merve Gorguner, Giorgia Line, Martin Werner, and Paul Valdes
Geosci. Model Dev., 18, 8129–8142, https://doi.org/10.5194/gmd-18-8129-2025, https://doi.org/10.5194/gmd-18-8129-2025, 2025
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We describe a new development in a state-of-the-art computer atmosphere model, which follows the movement of the model’s water. This provides an efficient way to track all the model's rain and snow back to the average location of the evaporative source, as shown in a present-day simulation. The new scheme can be used in simulations of the future to predict how sources of regional rain or snowfall might change owing to human actions, providing useful information for water management purposes.
Selvakumar Vishnupriya, Michael Sprenger, Hanna Joos, and Heini Wernli
Weather Clim. Dynam., 6, 1195–1219, https://doi.org/10.5194/wcd-6-1195-2025, https://doi.org/10.5194/wcd-6-1195-2025, 2025
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Extratropical cyclones feature rapidly ascending airstreams known as warm conveyor belts, which could influence upper-level flow dynamics. This study classifies interactions between warm conveyor belt outflows and the jet stream into four types: no interactions, ridges, blocks, and tropospheric cutoffs. We use reanalysis data to demonstrate that the interaction type depends on the structure of the ambient flow than on the outflow, improving our understanding of extratropical flow variability.
Louise C. Sime, Rahul Sivankutty, Irene Malmierca-Vallet, Sentia Goursaud Oger, Allegra N. LeGrande, Erin L. McClymont, Agatha de Boer, Alexandre Cauquoin, and Martin Werner
Clim. Past, 21, 1725–1753, https://doi.org/10.5194/cp-21-1725-2025, https://doi.org/10.5194/cp-21-1725-2025, 2025
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We used climate models to study how stable water isotopes in ice cores changed in the Arctic and Antarctica during the warm Last Interglacial (LIG) period. Whilst standard simulations underestimate polar warming, when the effects of ice sheet meltwater from the preceding deglaciation are included, there is a much better match with observations. Findings suggest that previous estimates of LIG Arctic warming were too high. Understanding these past polar changes can help improve future predictions.
Killian P. Brennan, Iris Thurnherr, Michael Sprenger, and Heini Wernli
Nat. Hazards Earth Syst. Sci., 25, 3693–3712, https://doi.org/10.5194/nhess-25-3693-2025, https://doi.org/10.5194/nhess-25-3693-2025, 2025
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Hailstorms can cause severe damage to homes, crops, and infrastructure. Using high-resolution climate simulations, we tracked thousands of hailstorms across Europe to study future changes. Large hail will become more frequent, hail-covered areas will expand, and instances of extreme hail combined with heavy rain will double. These shifts could increase risks for communities and businesses, highlighting the need for better preparedness and adaptation.
Luise J. Fischer, David N. Bresch, Dominik Büeler, Christian M. Grams, Robin Noyelle, Matthias Röthlisberger, and Heini Wernli
Weather Clim. Dynam., 6, 1027–1043, https://doi.org/10.5194/wcd-6-1027-2025, https://doi.org/10.5194/wcd-6-1027-2025, 2025
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Atmospheric flows over the North Atlantic can be meaningfully classified into weather regimes, and climate simulations suggest that the regime frequencies might change in the future. We provide a quantitative framework that helps assess whether these regime frequency changes are relevant to understanding climate change signals in precipitation. At least in our example application, in most regions, regime frequency changes explain little of the projected precipitation changes.
Tanguy Jonville, Maurus Borne, Cyrille Flamant, Juan Cuesta, Olivier Bock, Pierre Bosser, Christophe Lavaysse, Andreas Fink, and Peter Knippertz
Atmos. Chem. Phys., 25, 9765–9786, https://doi.org/10.5194/acp-25-9765-2025, https://doi.org/10.5194/acp-25-9765-2025, 2025
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Tropical waves structure the atmosphere. Four types of tropical waves (equatorial Rossby – ER, Kelvin, MRG-TD1, and MRG-TD2 – mixed Rossby gravity–tropical depressions) are studied using filters, satellite measurements, and in situ data from the Clouds–Atmosphere Dynamics–Dust Interaction in West Africa (CADDIWA) campaign held in September 2021 in Cabo Verde. ER waves impact temperature and humidity above 2500 m, MRG-TD1 around 3500 m, and MRG-TD2 around 2000 m. Interactions between these waves favor tropical cyclone formation.
Kalpana Hamal and Stephan Pfahl
Weather Clim. Dynam., 6, 879–899, https://doi.org/10.5194/wcd-6-879-2025, https://doi.org/10.5194/wcd-6-879-2025, 2025
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This study investigates the global drivers of sudden temperature changes from one day to the next using observational data and trajectory analysis. In extratropical regions, these shifts are mainly driven by air mass movements linked to circulation patterns. In tropical areas, local factors like cloud cover play a key role. Understanding these mechanisms improves predictions of extreme-temperature events, aiding in better preparation and mitigation strategies.
Daniele Zannoni, Hans Christian Steen-Larsen, Harald Sodemann, Iris Thurnherr, Cyrille Flamant, Patrick Chazette, Julien Totems, Martin Werner, and Myriam Raybaut
Atmos. Chem. Phys., 25, 9471–9495, https://doi.org/10.5194/acp-25-9471-2025, https://doi.org/10.5194/acp-25-9471-2025, 2025
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High-resolution airborne observations reveal that mixing between the free troposphere and surface evapotranspiration flux primarily modulates the water vapor isotopic composition in the lower troposphere. Water vapor isotope structure variations occur on the scale of hundreds of meters, underlining the utility of stable isotopes for studying microscale atmospheric dynamics. This study also provides the basis for better validation of water vapor isotope remote sensing retrievals with surface observations.
Hu Yang, Xiaoxu Shi, Xulong Wang, Qingsong Liu, Yi Zhong, Xiaodong Liu, Youbin Sun, Yanjun Cai, Fei Liu, Gerrit Lohmann, Martin Werner, Zhimin Jian, Tainã M. L. Pinho, Hai Cheng, Lijuan Lu, Jiping Liu, Chao-Yuan Yang, Qinghua Yang, Yongyun Hu, Xing Cheng, Jingyu Zhang, and Dake Chen
Clim. Past, 21, 1263–1279, https://doi.org/10.5194/cp-21-1263-2025, https://doi.org/10.5194/cp-21-1263-2025, 2025
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For 1 century, the hemispheric summer insolation is proposed as a key pacemaker of astronomical climate change. However, an increasing number of geologic records reveal that the low-latitude hydrological cycle shows asynchronous precessional evolutions that are very often out of phase with the summer insolation. Here, we propose that the astronomically driven low-latitude hydrological cycle is not paced by summer insolation but by shifting perihelion.
George Pacey, Stephan Pfahl, and Lisa Schielicke
Weather Clim. Dynam., 6, 695–713, https://doi.org/10.5194/wcd-6-695-2025, https://doi.org/10.5194/wcd-6-695-2025, 2025
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Cold fronts are often associated with areas of intense precipitation (cells) in the warm season, but the drivers and environments of cells at different locations relative to the front are not well-understood. We show that cells ahead of the surface front have the highest amount of environmental instability and moisture. Also, low-level lifting is maximised ahead of the surface front and upper-level lifting is particularly important for cell initiation behind the front.
Killian P. Brennan, Michael Sprenger, André Walser, Marco Arpagaus, and Heini Wernli
Weather Clim. Dynam., 6, 645–668, https://doi.org/10.5194/wcd-6-645-2025, https://doi.org/10.5194/wcd-6-645-2025, 2025
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We studied severe hailstorms that occurred in Switzerland on 28 June 2021 using a weather prediction model to understand how they evolved. We found that the storms moved toward areas with more storm energy. Hailfall was quickly followed by heavy rain. Just before the storms died out, the air feeding them stopped coming from near the ground. We also observed a delay between different types of precipitation forming in the incoming air.
Christopher Johannes Diekmann, Matthias Schneider, Peter Knippertz, Tim Trent, Hartmut Boesch, Amelie Ninja Roehling, John Worden, Benjamin Ertl, Farahnaz Khosrawi, and Frank Hase
Atmos. Chem. Phys., 25, 5409–5431, https://doi.org/10.5194/acp-25-5409-2025, https://doi.org/10.5194/acp-25-5409-2025, 2025
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The West African Monsoon is the main source of rainfall over West Africa, and understanding the development of the monsoon remains challenging due to complex interactions of atmospheric processes. We make use of new satellite datasets of isotopes in tropospheric water vapour to characterize processes controlling the monsoon convection. We find that comparing different water vapour isotopes reveals effects of rain–vapour interactions and air mass transport.
Katharina Hartmuth, Heini Wernli, and Lukas Papritz
Weather Clim. Dynam., 6, 505–520, https://doi.org/10.5194/wcd-6-505-2025, https://doi.org/10.5194/wcd-6-505-2025, 2025
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In this study, we use large-ensemble climate model simulations to analyze extreme winters in the Barents Sea in a changing climate. We find that variability in both atmospheric processes and sea ice conditions determines the formation of such seasons in the present-day climate. The reduction in sea ice variability results in a decreasing importance of surface boundary conditions in a warmer climate, while the robust link shown for surface weather systems persists.
Nicolai Krieger, Heini Wernli, Michael Sprenger, and Christian Kühnlein
Weather Clim. Dynam., 6, 447–469, https://doi.org/10.5194/wcd-6-447-2025, https://doi.org/10.5194/wcd-6-447-2025, 2025
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This study investigates the Laseyer, a local windstorm in a narrow Swiss valley characterized by strong southeasterly winds during northwesterly ambient flow. Using large-eddy simulations (LESs) with 30 m grid spacing, this is the first study to reveal that the extreme gusts in the valley are caused by an amplifying interplay of two recirculation regions. Modifying terrain and ambient wind conditions affects the windstorm's intensity and highlights the importance of topographic details in LES.
Joëlle C. Rieder, Franziska Aemisegger, Elad Dente, and Moshe Armon
Hydrol. Earth Syst. Sci., 29, 1395–1427, https://doi.org/10.5194/hess-29-1395-2025, https://doi.org/10.5194/hess-29-1395-2025, 2025
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The Sahara was wetter in the past and may become wetter in the future. Lake remnants are evidence of the desert’s wetter past. If the Sahara gets wetter in the future, these lakes may serve as a water resource. However, it is unclear how these lakes get filled and how moisture is carried into the desert and converted into rain in the first place. Therefore, we examine processes currently leading to the filling of a dry lake in the Sahara, which can help assess future water availability.
Henry Schoeller, Robin Chemnitz, Péter Koltai, Maximilian Engel, and Stephan Pfahl
Nonlin. Processes Geophys., 32, 51–73, https://doi.org/10.5194/npg-32-51-2025, https://doi.org/10.5194/npg-32-51-2025, 2025
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We identify spatially coherent air streams into atmospheric blockings, which are important weather phenomena. By adapting mathematical methods to the atmosphere, we confirm previous findings. Our work shows that spatially coherent air streams featuring cloud formation correlate with strengthening of the blocking. The developed framework also allows for statements about the spatial behavior of the air parcels as a whole and indicates that blockings reduce the dispersion of the air parcels.
Kelley C. Wells, Dylan B. Millet, Jared F. Brewer, Vivienne H. Payne, Karen E. Cady-Pereira, Rick Pernak, Susan Kulawik, Corinne Vigouroux, Nicholas Jones, Emmanuel Mahieu, Maria Makarova, Tomoo Nagahama, Ivan Ortega, Mathias Palm, Kimberly Strong, Matthias Schneider, Dan Smale, Ralf Sussmann, and Minqiang Zhou
Atmos. Meas. Tech., 18, 695–716, https://doi.org/10.5194/amt-18-695-2025, https://doi.org/10.5194/amt-18-695-2025, 2025
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Atmospheric volatile organic compounds (VOCs) affect both air quality and climate. Satellite measurements can help us to assess and predict their global impacts. We present new decadal (2012–2023) measurements of four key VOCs – methanol, ethene, ethyne, and hydrogen cyanide (HCN) – from the Cross-track Infrared Sounder. The measurements reflect emissions from major forests, wildfires, and industry and provide new information to advance understanding of these sources and their changes over time.
Qinggang Gao, Emilie Capron, Louise C. Sime, Rachael H. Rhodes, Rahul Sivankutty, Xu Zhang, Bette L. Otto-Bliesner, and Martin Werner
Clim. Past, 21, 419–440, https://doi.org/10.5194/cp-21-419-2025, https://doi.org/10.5194/cp-21-419-2025, 2025
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Marine sediment and ice core records suggest a warmer Southern Ocean and Antarctica at the early last interglacial, ~127 000 years ago. However, when only forced by orbital parameters and greenhouse gas concentrations during that period, state-of-the-art climate models do not reproduce the magnitude of warming. Here we show that much of the warming at southern middle to high latitudes can be reproduced by a UK climate model, HadCM3, with a 3000-year freshwater forcing over the North Atlantic.
Hanin Binder and Heini Wernli
Weather Clim. Dynam., 6, 151–170, https://doi.org/10.5194/wcd-6-151-2025, https://doi.org/10.5194/wcd-6-151-2025, 2025
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This study presents a systematic analysis of frequency anomalies and characteristics of extratropical cyclones during extremely wet, dry, windy, and calm winter and summer seasons in the extratropics based on 1050 years of present-day climate simulations. We show that anomalies in cyclone frequency, intensity, and stationarity are crucial to the occurrence of many extreme seasons and that these anomaly patterns exhibit substantial regional and seasonal variability.
Stefano Ubbiali, Christian Kühnlein, Christoph Schär, Linda Schlemmer, Thomas C. Schulthess, Michael Staneker, and Heini Wernli
Geosci. Model Dev., 18, 529–546, https://doi.org/10.5194/gmd-18-529-2025, https://doi.org/10.5194/gmd-18-529-2025, 2025
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We explore a high-level programming model for porting numerical weather prediction (NWP) model codes to graphics processing units (GPUs). We present a Python rewrite with the domain-specific library GT4Py (GridTools for Python) of two renowned cloud microphysics schemes and the associated tangent-linear and adjoint algorithms. We find excellent portability, competitive GPU performance, robust execution on diverse computing architectures, and enhanced code maintainability and user productivity.
Matthias Fischer, Peter Knippertz, and Carsten Proppe
Weather Clim. Dynam., 6, 113–130, https://doi.org/10.5194/wcd-6-113-2025, https://doi.org/10.5194/wcd-6-113-2025, 2025
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The West African monsoon is vital for millions but difficult to represent with numerical models. Our research aims at improving monsoon simulations by optimizing three model parameters – entrainment rate, ice fall speed, and soil moisture evaporation – using an advanced surrogate-based multi-objective optimization framework. Results show that tuning these parameters can sometimes improve certain monsoon characteristics, however at the expense of others, highlighting the power of our approach.
Inès Ollivier, Hans Christian Steen-Larsen, Barbara Stenni, Laurent Arnaud, Mathieu Casado, Alexandre Cauquoin, Giuliano Dreossi, Christophe Genthon, Bénédicte Minster, Ghislain Picard, Martin Werner, and Amaëlle Landais
The Cryosphere, 19, 173–200, https://doi.org/10.5194/tc-19-173-2025, https://doi.org/10.5194/tc-19-173-2025, 2025
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The role of post-depositional processes taking place at the ice sheet's surface on the water stable isotope signal measured in polar ice cores is not fully understood. Using field observations and modelling results, we show that the original precipitation isotopic signal at Dome C, East Antarctica, is modified by post-depositional processes and provide the first quantitative estimation of their mean impact on the isotopic signal observed in the snow.
Stephanie Mayer, Martin Hendrick, Adrien Michel, Bettina Richter, Jürg Schweizer, Heini Wernli, and Alec van Herwijnen
The Cryosphere, 18, 5495–5517, https://doi.org/10.5194/tc-18-5495-2024, https://doi.org/10.5194/tc-18-5495-2024, 2024
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Understanding the impact of climate change on snow avalanche activity is crucial for safeguarding lives and infrastructure. Here, we project changes in avalanche activity in the Swiss Alps throughout the 21st century. Our findings reveal elevation-dependent patterns of change, indicating a decrease in dry-snow avalanches alongside an increase in wet-snow avalanches at elevations above the current treeline. These results underscore the necessity to revisit measures for avalanche risk mitigation.
Heini Wernli and Suzanne L. Gray
Weather Clim. Dynam., 5, 1299–1408, https://doi.org/10.5194/wcd-5-1299-2024, https://doi.org/10.5194/wcd-5-1299-2024, 2024
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The science of extratropical dynamics has reached a new level where the interplay of dry dynamics with effects of latent heating in clouds and other diabatic processes is considered central to the field. This review documents how research about the role of diabatic processes evolved over more than a century; it highlights that progress relied essentially on the integration of theory, field campaigns, novel diagnostics, and numerical modelling, and it outlines avenues for future research.
Sonja Wahl, Benjamin Walter, Franziska Aemisegger, Luca Bianchi, and Michael Lehning
The Cryosphere, 18, 4493–4515, https://doi.org/10.5194/tc-18-4493-2024, https://doi.org/10.5194/tc-18-4493-2024, 2024
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Wind-driven airborne transport of snow is a frequent phenomenon in snow-covered regions and a process difficult to study in the field as it is unfolding over large distances. Thus, we use a ring wind tunnel with infinite fetch positioned in a cold laboratory to study the evolution of the shape and size of airborne snow. With the help of stable water isotope analyses, we identify the hitherto unobserved process of airborne snow metamorphism that leads to snow particle rounding and growth.
Selina M. Kiefer, Patrick Ludwig, Sebastian Lerch, Peter Knippertz, and Joaquim G. Pinto
EGUsphere, https://doi.org/10.5194/egusphere-2024-2955, https://doi.org/10.5194/egusphere-2024-2955, 2024
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Weather forecasts 14 days in advance generally have a low skill but not always. We identify reasons thereof depending on the atmospheric flow, shown by Weather Regimes (WRs). If the WRs during the forecasts follow climatological patterns, forecast skill is increased. The forecast of a cold-wave day is better when the European Blocking WR (high pressure around the British Isles) is present a few days before a cold-wave day. These results can be used to assess the reliability of predictions.
Matthias Schneider, Kinya Toride, Farahnaz Khosrawi, Frank Hase, Benjamin Ertl, Christopher J. Diekmann, and Kei Yoshimura
Atmos. Meas. Tech., 17, 5243–5259, https://doi.org/10.5194/amt-17-5243-2024, https://doi.org/10.5194/amt-17-5243-2024, 2024
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Despite its importance for extreme weather and climate feedbacks, atmospheric convection is not well constrained. This study assesses the potential of novel tropospheric water vapour isotopologue satellite observations for improving the analyses of convective events. We find that the impact of the isotopologues is small for stable atmospheric conditions but significant for unstable conditions, which have the strongest societal impacts (e.g. storms and flooding).
Florian Ruff and Stephan Pfahl
Nat. Hazards Earth Syst. Sci., 24, 2939–2952, https://doi.org/10.5194/nhess-24-2939-2024, https://doi.org/10.5194/nhess-24-2939-2024, 2024
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High-impact river floods are often caused by extreme precipitation. Flood protection relies on reliable estimates of the return values. Observational time series are too short for a precise calculation. Here, 100-year return values of daily precipitation are estimated on a global grid based on a large set of model-generated precipitation events from ensemble weather prediction. The statistical uncertainties in the return values can be substantially reduced compared to observational estimates.
Giuliano Dreossi, Mauro Masiol, Barbara Stenni, Daniele Zannoni, Claudio Scarchilli, Virginia Ciardini, Mathieu Casado, Amaëlle Landais, Martin Werner, Alexandre Cauquoin, Giampietro Casasanta, Massimo Del Guasta, Vittoria Posocco, and Carlo Barbante
The Cryosphere, 18, 3911–3931, https://doi.org/10.5194/tc-18-3911-2024, https://doi.org/10.5194/tc-18-3911-2024, 2024
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Oxygen and hydrogen stable isotopes have been extensively used to reconstruct past temperatures, with precipitation representing the input signal of the isotopic records in ice cores. We present a 10-year record of stable isotopes in daily precipitation at Concordia Station: this is the longest record for inland Antarctica and represents a benchmark for quantifying post-depositional processes and improving the paleoclimate interpretation of ice cores.
Ellina Agayar, Franziska Aemisegger, Moshe Armon, Alexander Scherrmann, and Heini Wernli
Nat. Hazards Earth Syst. Sci., 24, 2441–2459, https://doi.org/10.5194/nhess-24-2441-2024, https://doi.org/10.5194/nhess-24-2441-2024, 2024
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This study presents the results of a climatological investigation of extreme precipitation events (EPEs) in Ukraine for the period 1979–2019. During all seasons EPEs are associated with pronounced upper-level potential vorticity (PV) anomalies. In addition, we find distinct seasonal and regional differences in moisture sources. Several extreme precipitation cases demonstrate the importance of these processes, complemented by a detailed synoptic analysis.
Seraphine Hauser, Franziska Teubler, Michael Riemer, Peter Knippertz, and Christian M. Grams
Weather Clim. Dynam., 5, 633–658, https://doi.org/10.5194/wcd-5-633-2024, https://doi.org/10.5194/wcd-5-633-2024, 2024
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Blocking over Greenland has substantial impacts on the weather and climate in mid- and high latitudes. This study applies a quasi-Lagrangian thinking on the dynamics of Greenland blocking and reveals two pathways of anticyclonic anomalies linked to the block. Moist processes were found to play a dominant role in the formation and maintenance of blocking. This emphasizes the necessity of the correct representation of moist processes in weather and climate models to realistically depict blocking.
Qiansi Tu, Frank Hase, Kai Qin, Jason Blake Cohen, Farahnaz Khosrawi, Xinrui Zou, Matthias Schneider, and Fan Lu
Atmos. Chem. Phys., 24, 4875–4894, https://doi.org/10.5194/acp-24-4875-2024, https://doi.org/10.5194/acp-24-4875-2024, 2024
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Four-year satellite observations of XCH4 are used to derive CH4 emissions in three regions of China’s coal-rich Shanxi province. The wind-assigned anomalies for two opposite wind directions are calculated, and the estimated emission rates are comparable to the current bottom-up inventory but lower than the CAMS and EDGAR inventories. This research enhances the understanding of emissions in Shanxi and supports climate mitigation strategies by validating emission inventories.
Katharina Heitmann, Michael Sprenger, Hanin Binder, Heini Wernli, and Hanna Joos
Weather Clim. Dynam., 5, 537–557, https://doi.org/10.5194/wcd-5-537-2024, https://doi.org/10.5194/wcd-5-537-2024, 2024
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Warm conveyor belts (WCBs) are coherently ascending air streams that occur in extratropical cyclones where they form precipitation and often affect the large-scale flow. We quantified the key characteristics and impacts of WCBs and linked them to different phases in the cyclone life cycle and to different WCB branches. A climatology of these metrics revealed that WCBs are most intense during cyclone intensification and that the cyclonic and anticyclonic WCB branches show distinct differences.
Amaelle Landais, Cécile Agosta, Françoise Vimeux, Olivier Magand, Cyrielle Solis, Alexandre Cauquoin, Niels Dutrievoz, Camille Risi, Christophe Leroy-Dos Santos, Elise Fourré, Olivier Cattani, Olivier Jossoud, Bénédicte Minster, Frédéric Prié, Mathieu Casado, Aurélien Dommergue, Yann Bertrand, and Martin Werner
Atmos. Chem. Phys., 24, 4611–4634, https://doi.org/10.5194/acp-24-4611-2024, https://doi.org/10.5194/acp-24-4611-2024, 2024
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We have monitored water vapor isotopes since January 2020 on Amsterdam Island in the Indian Ocean. We show 11 periods associated with abrupt negative excursions of water vapor δ18Ο. Six of these events show a decrease in gaseous elemental mercury, suggesting subsidence of air from a higher altitude. Accurately representing the water isotopic signal during these cold fronts is a real challenge for the atmospheric components of Earth system models equipped with water isotopes.
Matthias Fischer, Peter Knippertz, Roderick van der Linden, Alexander Lemburg, Gregor Pante, Carsten Proppe, and John H. Marsham
Weather Clim. Dynam., 5, 511–536, https://doi.org/10.5194/wcd-5-511-2024, https://doi.org/10.5194/wcd-5-511-2024, 2024
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Our research enhances the understanding of the complex dynamics within the West African monsoon system by analyzing the impact of specific model parameters on its characteristics. Employing surrogate models, we identified critical factors such as the entrainment rate and the fall velocity of ice. Precise definition of these parameters in weather models could improve forecast accuracy, thus enabling better strategies to manage and reduce the impact of weather events.
Alexander Scherrmann, Heini Wernli, and Emmanouil Flaounas
Weather Clim. Dynam., 5, 419–438, https://doi.org/10.5194/wcd-5-419-2024, https://doi.org/10.5194/wcd-5-419-2024, 2024
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We show that the formation of Mediterranean cyclones follows the presence of cyclones over the North Atlantic. The distinct regions of cyclone activity in the Mediterranean in the different seasons can be linked to the atmospheric state, in particular the position of the polar jet over the North Atlantic. With this we now better understand the processes that lead to the formation of Mediterranean cyclones. We used a novel simulation framework in which we directly show and probe this connection.
Moein Mellat, Amy R. Macfarlane, Camilla F. Brunello, Martin Werner, Martin Schneebeli, Ruzica Dadic, Stefanie Arndt, Kaisa-Riikka Mustonen, Jeffrey M. Welker, and Hanno Meyer
EGUsphere, https://doi.org/10.5194/egusphere-2024-719, https://doi.org/10.5194/egusphere-2024-719, 2024
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Our research, utilizing data from the Arctic MOSAiC expedition, reveals how snow on Arctic sea ice changes due to weather conditions. By analyzing snow samples collected over a year, we found differences in snow layers that tell us about their origins and how they've been affected by the environment. We discovered variations in snow and vapour that reflect the influence of weather patterns and surface processes like wind and sublimation.
Esther S. Breuninger, Julie Tolu, Iris Thurnherr, Franziska Aemisegger, Aryeh Feinberg, Sylvain Bouchet, Jeroen E. Sonke, Véronique Pont, Heini Wernli, and Lenny H. E. Winkel
Atmos. Chem. Phys., 24, 2491–2510, https://doi.org/10.5194/acp-24-2491-2024, https://doi.org/10.5194/acp-24-2491-2024, 2024
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Atmospheric deposition is an important source of selenium (Se) and other health-relevant trace elements in surface environments. We found that the variability in elemental concentrations in atmospheric deposition reflects not only changes in emission sources but also weather conditions during atmospheric removal. Depending on the sources and if Se is derived more locally or from further away, the Se forms can be different, affecting the bioavailability of Se atmospherically supplied to soils.
Qinggang Gao, Louise C. Sime, Alison J. McLaren, Thomas J. Bracegirdle, Emilie Capron, Rachael H. Rhodes, Hans Christian Steen-Larsen, Xiaoxu Shi, and Martin Werner
The Cryosphere, 18, 683–703, https://doi.org/10.5194/tc-18-683-2024, https://doi.org/10.5194/tc-18-683-2024, 2024
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Antarctic precipitation is a crucial component of the climate system. Its spatio-temporal variability impacts sea level changes and the interpretation of water isotope measurements in ice cores. To better understand its climatic drivers, we developed water tracers in an atmospheric model to identify moisture source conditions from which precipitation originates. We find that mid-latitude surface winds exert an important control on moisture availability for Antarctic precipitation.
Edgar Dolores-Tesillos and Stephan Pfahl
Weather Clim. Dynam., 5, 163–179, https://doi.org/10.5194/wcd-5-163-2024, https://doi.org/10.5194/wcd-5-163-2024, 2024
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In a warmer climate, the winter extratropical cyclones over the North Atlantic basin are expected to have a larger footprint of strong winds. Dynamical changes at different altitudes are responsible for these wind changes. Based on backward trajectories using the CESM-LE simulations, we show that the diabatic processes gain relevance as the planet warms. For instance, changes in the radiative processes will play an important role in the upper-level cyclone dynamics.
Maurus Borne, Peter Knippertz, Martin Weissmann, Benjamin Witschas, Cyrille Flamant, Rosimar Rios-Berrios, and Peter Veals
Atmos. Meas. Tech., 17, 561–581, https://doi.org/10.5194/amt-17-561-2024, https://doi.org/10.5194/amt-17-561-2024, 2024
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This study assesses the quality of Aeolus wind measurements over the tropical Atlantic. The results identified the accuracy and precision of the Aeolus wind measurements and the potential source of errors. For instance, the study revealed atmospheric conditions that can deteriorate the measurement quality, such as weaker laser signal in cloudy or dusty conditions, and confirmed the presence of an orbital-dependant bias. These results can help to improve the Aeolus wind measurement algorithm.
Leonie Villiger and Franziska Aemisegger
Atmos. Chem. Phys., 24, 957–976, https://doi.org/10.5194/acp-24-957-2024, https://doi.org/10.5194/acp-24-957-2024, 2024
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Three numerical simulations performed with an isotope-enabled weather forecast model are used to investigate the cloud–circulation coupling between shallow trade-wind cumulus clouds and atmospheric circulations on different scales. It is shown that stable water isotopes near cloud base in the tropics reflect (1) the diel cycle of the atmospheric circulation, which drives the formation and dissipation of clouds, and (2) changes in the large-scale circulation over the North Atlantic.
Julian F. Quinting, Christian M. Grams, Edmund Kar-Man Chang, Stephan Pfahl, and Heini Wernli
Weather Clim. Dynam., 5, 65–85, https://doi.org/10.5194/wcd-5-65-2024, https://doi.org/10.5194/wcd-5-65-2024, 2024
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Research in the last few decades has revealed that rapidly ascending airstreams in extratropical cyclones have an important effect on the evolution of downstream weather and predictability. In this study, we show that the occurrence of these airstreams over the North Pacific is modulated by tropical convection. Depending on the modulation, known atmospheric circulation patterns evolve quite differently, which may affect extended-range predictions in the Atlantic–European region.
Hyunju Jung, Peter Knippertz, Yvonne Ruckstuhl, Robert Redl, Tijana Janjic, and Corinna Hoose
Weather Clim. Dynam., 4, 1111–1134, https://doi.org/10.5194/wcd-4-1111-2023, https://doi.org/10.5194/wcd-4-1111-2023, 2023
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A narrow rainfall belt in the tropics is an important feature for large-scale circulations and the global water cycle. The accurate simulation of this rainfall feature has been a long-standing problem, with the reasons behind that unclear. We present a novel diagnostic tool that allows us to disentangle processes important for rainfall, which changes due to modifications in model. Using our diagnostic tool, one can potentially identify sources of uncertainty in weather and climate models.
Christophe Leroy-Dos Santos, Elise Fourré, Cécile Agosta, Mathieu Casado, Alexandre Cauquoin, Martin Werner, Benedicte Minster, Frédéric Prié, Olivier Jossoud, Leila Petit, and Amaëlle Landais
The Cryosphere, 17, 5241–5254, https://doi.org/10.5194/tc-17-5241-2023, https://doi.org/10.5194/tc-17-5241-2023, 2023
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In the face of global warming, understanding the changing water cycle and temperatures in polar regions is crucial. These factors directly impact the balance of ice sheets in the Arctic and Antarctic. By studying the composition of water vapor, we gain insights into climate variations. Our 2-year study at Dumont d’Urville station, Adélie Land, offers valuable data to refine models. Additionally, we demonstrate how modeling aids in interpreting signals from ice core samples in the region.
George Pacey, Stephan Pfahl, Lisa Schielicke, and Kathrin Wapler
Nat. Hazards Earth Syst. Sci., 23, 3703–3721, https://doi.org/10.5194/nhess-23-3703-2023, https://doi.org/10.5194/nhess-23-3703-2023, 2023
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Cold fronts are often associated with areas of intense precipitation (cells) and sometimes with hazards such as flooding, hail and lightning. We find that cold-frontal cell days are associated with higher cell frequency and cells are typically more intense. We also show both spatially and temporally where cells are most frequent depending on their cell-front distance. These results are an important step towards a deeper understanding of cold-frontal storm climatology and improved forecasting.
Leonie Villiger, Marina Dütsch, Sandrine Bony, Marie Lothon, Stephan Pfahl, Heini Wernli, Pierre-Etienne Brilouet, Patrick Chazette, Pierre Coutris, Julien Delanoë, Cyrille Flamant, Alfons Schwarzenboeck, Martin Werner, and Franziska Aemisegger
Atmos. Chem. Phys., 23, 14643–14672, https://doi.org/10.5194/acp-23-14643-2023, https://doi.org/10.5194/acp-23-14643-2023, 2023
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This study evaluates three numerical simulations performed with an isotope-enabled weather forecast model and investigates the coupling between shallow trade-wind cumulus clouds and atmospheric circulations on different scales. We show that the simulations reproduce key characteristics of shallow trade-wind clouds as observed during the field experiment EUREC4A and that the spatial distribution of stable-water-vapour isotopes is shaped by the overturning circulation associated with these clouds.
Lea Eisenstein, Benedikt Schulz, Joaquim G. Pinto, and Peter Knippertz
Weather Clim. Dynam., 4, 981–999, https://doi.org/10.5194/wcd-4-981-2023, https://doi.org/10.5194/wcd-4-981-2023, 2023
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Mesoscale high-wind features within extratropical cyclones can cause immense damage. In Part 1 of this work, we introduced RAMEFI (RAndom-forest-based MEsoscale wind Feature Identification), an objective, flexible identification tool for these wind features based on a probabilistic random forest. Here, we use RAMEFI to compile a climatology of the features over 19 extended winter seasons over western and central Europe, focusing on relative occurrence, affected areas and further characteristics.
Xiaoxu Shi, Martin Werner, Hu Yang, Roberta D'Agostino, Jiping Liu, Chaoyuan Yang, and Gerrit Lohmann
Clim. Past, 19, 2157–2175, https://doi.org/10.5194/cp-19-2157-2023, https://doi.org/10.5194/cp-19-2157-2023, 2023
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The Last Glacial Maximum (LGM) marks the most recent extremely cold and dry time period of our planet. Using AWI-ESM, we quantify the relative importance of Earth's orbit, greenhouse gases (GHG) and ice sheets (IS) in determining the LGM climate. Our results suggest that both GHG and IS play important roles in shaping the LGM temperature. Continental ice sheets exert a major control on precipitation, atmospheric dynamics, and the intensity of El Niño–Southern Oscillation.
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.
Xiaoxu Shi, Alexandre Cauquoin, Gerrit Lohmann, Lukas Jonkers, Qiang Wang, Hu Yang, Yuchen Sun, and Martin Werner
Geosci. Model Dev., 16, 5153–5178, https://doi.org/10.5194/gmd-16-5153-2023, https://doi.org/10.5194/gmd-16-5153-2023, 2023
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We developed a new climate model with isotopic capabilities and simulated the pre-industrial and mid-Holocene periods. Despite certain regional model biases, the modeled isotope composition is in good agreement with observations and reconstructions. Based on our analyses, the observed isotope–temperature relationship in polar regions may have a summertime bias. Using daily model outputs, we developed a novel isotope-based approach to determine the onset date of the West African summer monsoon.
Valerian Hahn, Ralf Meerkötter, Christiane Voigt, Sonja Gisinger, Daniel Sauer, Valéry Catoire, Volker Dreiling, Hugh Coe, Cyrille Flamant, Stefan Kaufmann, Jonas Kleine, Peter Knippertz, Manuel Moser, Philip Rosenberg, Hans Schlager, Alfons Schwarzenboeck, and Jonathan Taylor
Atmos. Chem. Phys., 23, 8515–8530, https://doi.org/10.5194/acp-23-8515-2023, https://doi.org/10.5194/acp-23-8515-2023, 2023
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During the DACCIWA campaign in West Africa, we found a 35 % increase in the cloud droplet concentration that formed in a polluted compared with a less polluted environment and a decrease of 17 % in effective droplet diameter. Radiative transfer simulations, based on the measured cloud properties, reveal that these low-level polluted clouds radiate only 2.6 % more energy back to space, compared with a less polluted cloud. The corresponding additional decrease in temperature is rather small.
Mark J. Rodwell and Heini Wernli
Weather Clim. Dynam., 4, 591–615, https://doi.org/10.5194/wcd-4-591-2023, https://doi.org/10.5194/wcd-4-591-2023, 2023
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Midlatitude storms and their downstream impacts have a major impact on society, yet their prediction is especially prone to uncertainty. While this can never be fully eliminated, we find that the initial rate of growth of uncertainty varies for a range of forecast models. Examination of the model of the European Centre for Medium-Range Weather Forecasts (ECMWF) suggests ways in which uncertainty growth could be reduced, leading to sharper and more reliable forecasts over the first few days.
Alexandre Cauquoin, Ayako Abe-Ouchi, Takashi Obase, Wing-Le Chan, André Paul, and Martin Werner
Clim. Past, 19, 1275–1294, https://doi.org/10.5194/cp-19-1275-2023, https://doi.org/10.5194/cp-19-1275-2023, 2023
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Stable water isotopes are tracers of climate processes occurring in the hydrological cycle. They are widely used to reconstruct the past variations of polar temperature before the instrumental era thanks to their measurements in ice cores. However, the relationship between measured isotopes and temperature has large uncertainties. In our study, we investigate how the sea surface conditions (temperature, sea ice, ocean circulation) impact this relationship for a cold to warm climate change.
Florian Ruff and Stephan Pfahl
Weather Clim. Dynam., 4, 427–447, https://doi.org/10.5194/wcd-4-427-2023, https://doi.org/10.5194/wcd-4-427-2023, 2023
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In this study, we analyse the generic atmospheric processes of very extreme, 100-year precipitation events in large central European river catchments and the corresponding differences to less extreme events, based on a large time series (~1200 years) of simulated but realistic daily precipitation events from the ECMWF. Depending on the catchment, either dynamical mechanisms or thermodynamic conditions or a combination of both distinguish 100-year events from less extreme precipitation events.
Seraphine Hauser, Franziska Teubler, Michael Riemer, Peter Knippertz, and Christian M. Grams
Weather Clim. Dynam., 4, 399–425, https://doi.org/10.5194/wcd-4-399-2023, https://doi.org/10.5194/wcd-4-399-2023, 2023
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Blocking describes a flow configuration in the midlatitudes where stationary high-pressure systems block the propagation of weather systems. This study combines three individual perspectives that capture the dynamics and importance of various processes in the formation of a major blocking in 2016 from a weather regime perspective. In future work, this framework will enable a holistic view of the dynamics and the role of moist processes in different life cycle stages of blocked weather regimes.
Qiansi Tu, Frank Hase, Zihan Chen, Matthias Schneider, Omaira García, Farahnaz Khosrawi, Shuo Chen, Thomas Blumenstock, Fang Liu, Kai Qin, Jason Cohen, Qin He, Song Lin, Hongyan Jiang, and Dianjun Fang
Atmos. Meas. Tech., 16, 2237–2262, https://doi.org/10.5194/amt-16-2237-2023, https://doi.org/10.5194/amt-16-2237-2023, 2023
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Four-year TROPOMI observations are used to derive tropospheric NO2 emissions in two mega(cities) with high anthropogenic activity. Wind-assigned anomalies are calculated, and the emission rates and spatial patterns are estimated based on a machine learning algorithm. The results are in reasonable agreement with previous studies and the inventory. Our method is quite robust and can be used as a simple method to estimate the emissions of NO2 as well as other gases in other regions.
Charles G. Gertler, Paul A. O'Gorman, and Stephan Pfahl
Weather Clim. Dynam., 4, 361–379, https://doi.org/10.5194/wcd-4-361-2023, https://doi.org/10.5194/wcd-4-361-2023, 2023
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The relationship between the time-mean state of the atmosphere and aspects of atmospheric circulation drives general understanding of the atmospheric circulation. Here, we present new techniques to calculate local properties of the time-mean atmosphere and relate those properties to aspects of extratropical circulation with important implications for weather. This relationship should help connect changes to the atmosphere, such as under global warming, to changes in midlatitude weather.
Patrick Ludwig, Florian Ehmele, Mário J. Franca, Susanna Mohr, Alberto Caldas-Alvarez, James E. Daniell, Uwe Ehret, Hendrik Feldmann, Marie Hundhausen, Peter Knippertz, Katharina Küpfer, Michael Kunz, Bernhard Mühr, Joaquim G. Pinto, Julian Quinting, Andreas M. Schäfer, Frank Seidel, and Christina Wisotzky
Nat. Hazards Earth Syst. Sci., 23, 1287–1311, https://doi.org/10.5194/nhess-23-1287-2023, https://doi.org/10.5194/nhess-23-1287-2023, 2023
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Heavy precipitation in July 2021 led to widespread floods in western Germany and neighboring countries. The event was among the five heaviest precipitation events of the past 70 years in Germany, and the river discharges exceeded by far the statistical 100-year return values. Simulations of the event under future climate conditions revealed a strong and non-linear effect on flood peaks: for +2 K global warming, an 18 % increase in rainfall led to a 39 % increase of the flood peak in the Ahr river.
Mauro Hermann, Matthias Röthlisberger, Arthur Gessler, Andreas Rigling, Cornelius Senf, Thomas Wohlgemuth, and Heini Wernli
Biogeosciences, 20, 1155–1180, https://doi.org/10.5194/bg-20-1155-2023, https://doi.org/10.5194/bg-20-1155-2023, 2023
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This study examines the multi-annual meteorological history of low-forest-greenness events in Europe's temperate and Mediterranean biome in 2002–2022. We systematically identify anomalies in temperature, precipitation, and weather systems as event precursors, with noteworthy differences between the two biomes. We also quantify the impact of the most extensive event in 2022 (37 % coverage), underlining the importance of understanding the forest–meteorology interaction in a changing climate.
Susanna Mohr, Uwe Ehret, Michael Kunz, Patrick Ludwig, Alberto Caldas-Alvarez, James E. Daniell, Florian Ehmele, Hendrik Feldmann, Mário J. Franca, Christian Gattke, Marie Hundhausen, Peter Knippertz, Katharina Küpfer, Bernhard Mühr, Joaquim G. Pinto, Julian Quinting, Andreas M. Schäfer, Marc Scheibel, Frank Seidel, and Christina Wisotzky
Nat. Hazards Earth Syst. Sci., 23, 525–551, https://doi.org/10.5194/nhess-23-525-2023, https://doi.org/10.5194/nhess-23-525-2023, 2023
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The flood event in July 2021 was one of the most severe disasters in Europe in the last half century. The objective of this two-part study is a multi-disciplinary assessment that examines the complex process interactions in different compartments, from meteorology to hydrological conditions to hydro-morphological processes to impacts on assets and environment. In addition, we address the question of what measures are possible to generate added value to early response management.
Adriana Bailey, Franziska Aemisegger, Leonie Villiger, Sebastian A. Los, Gilles Reverdin, Estefanía Quiñones Meléndez, Claudia Acquistapace, Dariusz B. Baranowski, Tobias Böck, Sandrine Bony, Tobias Bordsdorff, Derek Coffman, Simon P. de Szoeke, Christopher J. Diekmann, Marina Dütsch, Benjamin Ertl, Joseph Galewsky, Dean Henze, Przemyslaw Makuch, David Noone, Patricia K. Quinn, Michael Rösch, Andreas Schneider, Matthias Schneider, Sabrina Speich, Bjorn Stevens, and Elizabeth J. Thompson
Earth Syst. Sci. Data, 15, 465–495, https://doi.org/10.5194/essd-15-465-2023, https://doi.org/10.5194/essd-15-465-2023, 2023
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One of the novel ways EUREC4A set out to investigate trade wind clouds and their coupling to the large-scale circulation was through an extensive network of isotopic measurements in water vapor, precipitation, and seawater. Samples were taken from the island of Barbados, from aboard two aircraft, and from aboard four ships. This paper describes the full collection of EUREC4A isotopic in situ data and guides readers to complementary remotely sensed water vapor isotope ratios.
Alexander Scherrmann, Heini Wernli, and Emmanouil Flaounas
Weather Clim. Dynam., 4, 157–173, https://doi.org/10.5194/wcd-4-157-2023, https://doi.org/10.5194/wcd-4-157-2023, 2023
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We investigate the dynamical origin of the lower-atmospheric potential vorticity (PV; linked to the intensity of cyclones) in Mediterranean cyclones. We quantify the contribution of the cyclone and the environment by tracing PV backward in time and space and linking it to the track of the cyclone. We find that the lower-tropospheric PV is produced shortly before the cyclone's stage of highest intensity. We investigate the driving processes and use a global dataset and a process-resolving one.
Hanna Joos, Michael Sprenger, Hanin Binder, Urs Beyerle, and Heini Wernli
Weather Clim. Dynam., 4, 133–155, https://doi.org/10.5194/wcd-4-133-2023, https://doi.org/10.5194/wcd-4-133-2023, 2023
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Warm conveyor belts (WCBs) are strongly ascending, cloud- and precipitation-forming airstreams in extratropical cyclones. In this study we assess their representation in a climate simulation and their changes under global warming. They become moister, become more intense, and reach higher altitudes in a future climate, implying that they potentially have an increased impact on the mid-latitude flow.
Andreas Schäfler, Michael Sprenger, Heini Wernli, Andreas Fix, and Martin Wirth
Atmos. Chem. Phys., 23, 999–1018, https://doi.org/10.5194/acp-23-999-2023, https://doi.org/10.5194/acp-23-999-2023, 2023
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In this study, airborne lidar profile measurements of H2O and O3 across a midlatitude jet stream are combined with analyses in tracer–trace space and backward trajectories. We highlight that transport and mixing processes in the history of the observed air masses are governed by interacting tropospheric weather systems on synoptic timescales. We show that these weather systems play a key role in the high variability of the paired H2O and O3 distributions near the tropopause.
Hanin Binder, Hanna Joos, Michael Sprenger, and Heini Wernli
Weather Clim. Dynam., 4, 19–37, https://doi.org/10.5194/wcd-4-19-2023, https://doi.org/10.5194/wcd-4-19-2023, 2023
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Warm conveyor belts (WCBs) are the main cloud- and precipitation-producing airstreams in extratropical cyclones. The latent heat release that occurs during cloud formation often contributes to the intensification of the associated cyclone. Based on the Community Earth System Model Large Ensemble coupled climate simulations, we show that WCBs and associated latent heating will become stronger in a future climate and be even more important for explosive cyclone intensification than in the present.
Lisa Schielicke and Stephan Pfahl
Weather Clim. Dynam., 3, 1439–1459, https://doi.org/10.5194/wcd-3-1439-2022, https://doi.org/10.5194/wcd-3-1439-2022, 2022
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Projected future heatwaves in many European regions will be even warmer than the mean increase in summer temperature suggests. To identify the underlying thermodynamic and dynamic processes, we compare Lagrangian backward trajectories of airstreams associated with heatwaves in two time slices (1991–2000 and 2091–2100) in a large single-model ensemble (CEMS-LE). We find stronger future descent associated with adiabatic warming in some regions and increased future diabatic heating in most regions.
Farahnaz Khosrawi, Kinya Toride, Kei Yoshimura, Christopher Diekmann, Benjamin Ertl, Frank Hase, and Matthias Schneider
EGUsphere, https://doi.org/10.5194/egusphere-2022-1408, https://doi.org/10.5194/egusphere-2022-1408, 2022
Preprint withdrawn
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We assess with an Observation System Simulation Experiment the potential of mid-tropospheric water isotopologue data for constraining uncertainties in meteorological analysis fields in the tropics. Our assimilation experiments indicate that isotopologue observations have the potential to reduce the uncertainties of diabatic heating rates and precipitation in the tropics and in consequence offer potential for improving meteorological analysis in the tropical regions.
Jiajia Wang, Hongxi Pang, Shuangye Wu, Spruce W. Schoenemann, Ryu Uemura, Alexey Ekaykin, Martin Werner, Alexandre Cauquoin, Sentia Goursaud Oger, Summer Rupper, and Shugui Hou
Earth Syst. Sci. Data Discuss., https://doi.org/10.5194/essd-2022-384, https://doi.org/10.5194/essd-2022-384, 2022
Revised manuscript not accepted
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Stable water isotopic observations in surface snow over Antarctica provide a basis for validating isotopic models and interpreting Antarctic ice core records. This study presents a new compilation of Antarctic surface snow isotopic dataset based on published and unpublished sources. The database has a wide range of potential applications in studying spatial distribution of water isotopes, model validation, and reconstruction and interpretation of Antarctic ice core records.
Alberto Caldas-Alvarez, Markus Augenstein, Georgy Ayzel, Klemens Barfus, Ribu Cherian, Lisa Dillenardt, Felix Fauer, Hendrik Feldmann, Maik Heistermann, Alexia Karwat, Frank Kaspar, Heidi Kreibich, Etor Emanuel Lucio-Eceiza, Edmund P. Meredith, Susanna Mohr, Deborah Niermann, Stephan Pfahl, Florian Ruff, Henning W. Rust, Lukas Schoppa, Thomas Schwitalla, Stella Steidl, Annegret H. Thieken, Jordis S. Tradowsky, Volker Wulfmeyer, and Johannes Quaas
Nat. Hazards Earth Syst. Sci., 22, 3701–3724, https://doi.org/10.5194/nhess-22-3701-2022, https://doi.org/10.5194/nhess-22-3701-2022, 2022
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In a warming climate, extreme precipitation events are becoming more frequent. To advance our knowledge on such phenomena, we present a multidisciplinary analysis of a selected case study that took place on 29 June 2017 in the Berlin metropolitan area. Our analysis provides evidence of the extremeness of the case from the atmospheric and the impacts perspectives as well as new insights on the physical mechanisms of the event at the meteorological and climate scales.
Lea Eisenstein, Benedikt Schulz, Ghulam A. Qadir, Joaquim G. Pinto, and Peter Knippertz
Weather Clim. Dynam., 3, 1157–1182, https://doi.org/10.5194/wcd-3-1157-2022, https://doi.org/10.5194/wcd-3-1157-2022, 2022
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Mesoscale high-wind features within extratropical cyclones can cause immense damage. Here, we present RAMEFI, a novel approach to objectively identify the wind features based on a probabilistic random forest. RAMEFI enables a wide range of applications such as probabilistic predictions for the occurrence or a multi-decadal climatology of these features, which will be the focus of Part 2 of the study, with the goal of improving wind and, specifically, wind gust forecasts in the long run.
Antoine Grisart, Mathieu Casado, Vasileios Gkinis, Bo Vinther, Philippe Naveau, Mathieu Vrac, Thomas Laepple, Bénédicte Minster, Frederic Prié, Barbara Stenni, Elise Fourré, Hans Christian Steen-Larsen, Jean Jouzel, Martin Werner, Katy Pol, Valérie Masson-Delmotte, Maria Hoerhold, Trevor Popp, and Amaelle Landais
Clim. Past, 18, 2289–2301, https://doi.org/10.5194/cp-18-2289-2022, https://doi.org/10.5194/cp-18-2289-2022, 2022
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This paper presents a compilation of high-resolution (11 cm) water isotopic records, including published and new measurements, for the last 800 000 years from the EPICA Dome C ice core, Antarctica. Using this new combined water isotopes (δ18O and δD) dataset, we study the variability and possible influence of diffusion at the multi-decadal to multi-centennial scale. We observe a stronger variability at the onset of the interglacial interval corresponding to a warm period.
Iris Thurnherr and Franziska Aemisegger
Atmos. Chem. Phys., 22, 10353–10373, https://doi.org/10.5194/acp-22-10353-2022, https://doi.org/10.5194/acp-22-10353-2022, 2022
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Stable water isotopes in marine boundary layer vapour are strongly influenced by the strength of air–sea fluxes. Here, we investigate a distinct vapour isotope signal observed in the warm sector of Southern Ocean cyclones. Single-process air parcel models are used together with high-resolution isotope-enabled simulations with the weather prediction model COSMOiso to improve our understanding of the importance of air–sea fluxes for the moisture cycling in the context of extratropical cyclones.
Omaira E. García, Esther Sanromá, Frank Hase, Matthias Schneider, Sergio Fabián León-Luis, Thomas Blumenstock, Eliezer Sepúlveda, Carlos Torres, Natalia Prats, Alberto Redondas, and Virgilio Carreño
Atmos. Meas. Tech., 15, 4547–4567, https://doi.org/10.5194/amt-15-4547-2022, https://doi.org/10.5194/amt-15-4547-2022, 2022
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Retrieving high-precision concentrations of atmospheric trace gases from FTIR (Fourier transform infrared) spectrometry requires a precise knowledge of the instrumental performance. In this context, this paper examines the impact on the ozone (O3) retrievals of several approaches used to characterise the instrumental line shape (ILS) function of ground-based FTIR spectrometers within NDACC (Network for the Detection of Atmospheric Composition Change).
Qiansi Tu, Matthias Schneider, Frank Hase, Farahnaz Khosrawi, Benjamin Ertl, Jaroslaw Necki, Darko Dubravica, Christopher J. Diekmann, Thomas Blumenstock, and Dianjun Fang
Atmos. Chem. Phys., 22, 9747–9765, https://doi.org/10.5194/acp-22-9747-2022, https://doi.org/10.5194/acp-22-9747-2022, 2022
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Three-year satellite observations and high-resolution model forecast of XCH4 are used to derive CH4 emissions in the USCB region, Poland – a region of intense coal mining activities. The wind-assigned anomalies for two opposite wind directions are calculated and the estimated emission rates are very close to the inventories and in reasonable agreement with the previous studies. Our method is quite robust and can serve as a simple method to estimate CH4 or CO2 emissions for other regions.
Matthias Schneider, Benjamin Ertl, Qiansi Tu, Christopher J. Diekmann, Farahnaz Khosrawi, Amelie N. Röhling, Frank Hase, Darko Dubravica, Omaira E. García, Eliezer Sepúlveda, Tobias Borsdorff, Jochen Landgraf, Alba Lorente, André Butz, Huilin Chen, Rigel Kivi, Thomas Laemmel, Michel Ramonet, Cyril Crevoisier, Jérome Pernin, Martin Steinbacher, Frank Meinhardt, Kimberly Strong, Debra Wunch, Thorsten Warneke, Coleen Roehl, Paul O. Wennberg, Isamu Morino, Laura T. Iraci, Kei Shiomi, Nicholas M. Deutscher, David W. T. Griffith, Voltaire A. Velazco, and David F. Pollard
Atmos. Meas. Tech., 15, 4339–4371, https://doi.org/10.5194/amt-15-4339-2022, https://doi.org/10.5194/amt-15-4339-2022, 2022
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We present a computationally very efficient method for the synergetic use of level 2 remote-sensing data products. We apply the method to IASI vertical profile and TROPOMI total column space-borne methane observations and thus gain sensitivity for the tropospheric methane partial columns, which is not achievable by the individual use of TROPOMI and IASI. These synergetic effects are evaluated theoretically and empirically by inter-comparisons to independent references of TCCON, AirCore, and GAW.
Janica C. Bühler, Josefine Axelsson, Franziska A. Lechleitner, Jens Fohlmeister, Allegra N. LeGrande, Madhavan Midhun, Jesper Sjolte, Martin Werner, Kei Yoshimura, and Kira Rehfeld
Clim. Past, 18, 1625–1654, https://doi.org/10.5194/cp-18-1625-2022, https://doi.org/10.5194/cp-18-1625-2022, 2022
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We collected and standardized the output of five isotope-enabled simulations for the last millennium and assess differences and similarities to records from a global speleothem database. Modeled isotope variations mostly arise from temperature differences. While lower-resolution speleothems do not capture extreme changes to the extent of models, they show higher variability on multi-decadal timescales. As no model excels in all comparisons, we advise a multi-model approach where possible.
Andries Jan de Vries, Franziska Aemisegger, Stephan Pfahl, and Heini Wernli
Atmos. Chem. Phys., 22, 8863–8895, https://doi.org/10.5194/acp-22-8863-2022, https://doi.org/10.5194/acp-22-8863-2022, 2022
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The Earth's water cycle contains the common H2O molecule but also the less abundant, heavier HDO. We use their different physical properties to study tropical ice clouds in model simulations of the West African monsoon. Isotope signals reveal different processes through which ice clouds form and decay in deep-convective and widespread cirrus. Previously observed variations in upper-tropospheric vapour isotopes are explained by microphysical processes in convective updraughts and downdraughts.
Xiaoxu Shi, Martin Werner, Carolin Krug, Chris M. Brierley, Anni Zhao, Endurance Igbinosa, Pascale Braconnot, Esther Brady, Jian Cao, Roberta D'Agostino, Johann Jungclaus, Xingxing Liu, Bette Otto-Bliesner, Dmitry Sidorenko, Robert Tomas, Evgeny M. Volodin, Hu Yang, Qiong Zhang, Weipeng Zheng, and Gerrit Lohmann
Clim. Past, 18, 1047–1070, https://doi.org/10.5194/cp-18-1047-2022, https://doi.org/10.5194/cp-18-1047-2022, 2022
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Since the orbital parameters of the past are different from today, applying the modern calendar to the past climate can lead to an artificial bias in seasonal cycles. With the use of multiple model outputs, we found that such a bias is non-ignorable and should be corrected to ensure an accurate comparison between modeled results and observational records, as well as between simulated past and modern climates, especially for the Last Interglacial.
Omaira Elena García, Esther Sanromá, Matthias Schneider, Frank Hase, Sergio Fabián León-Luis, Thomas Blumenstock, Eliezer Sepúlveda, Alberto Redondas, Virgilio Carreño, Carlos Torres, and Natalia Prats
Atmos. Meas. Tech., 15, 2557–2577, https://doi.org/10.5194/amt-15-2557-2022, https://doi.org/10.5194/amt-15-2557-2022, 2022
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Accurate observations of atmospheric ozone (O3) are essential to monitor in detail its key role in atmospheric chemistry. In this context, this paper has assessed the effect of using different retrieval strategies on the quality of O3 products from ground-based NDACC FTIR (Fourier transform infrared) spectrometry, with the aim of providing an improved O3 retrieval that could be applied at any NDACC FTIR station.
Sandrine Bony, Marie Lothon, Julien Delanoë, Pierre Coutris, Jean-Claude Etienne, Franziska Aemisegger, Anna Lea Albright, Thierry André, Hubert Bellec, Alexandre Baron, Jean-François Bourdinot, Pierre-Etienne Brilouet, Aurélien Bourdon, Jean-Christophe Canonici, Christophe Caudoux, Patrick Chazette, Michel Cluzeau, Céline Cornet, Jean-Philippe Desbios, Dominique Duchanoy, Cyrille Flamant, Benjamin Fildier, Christophe Gourbeyre, Laurent Guiraud, Tetyana Jiang, Claude Lainard, Christophe Le Gac, Christian Lendroit, Julien Lernould, Thierry Perrin, Frédéric Pouvesle, Pascal Richard, Nicolas Rochetin, Kevin Salaün, Alfons Schwarzenboeck, Guillaume Seurat, Bjorn Stevens, Julien Totems, Ludovic Touzé-Peiffer, Gilles Vergez, Jessica Vial, Leonie Villiger, and Raphaela Vogel
Earth Syst. Sci. Data, 14, 2021–2064, https://doi.org/10.5194/essd-14-2021-2022, https://doi.org/10.5194/essd-14-2021-2022, 2022
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The French ATR42 research aircraft participated in the EUREC4A international field campaign that took place in 2020 over the tropical Atlantic, east of Barbados. We present the extensive instrumentation of the aircraft, the research flights and the different measurements. We show that the ATR measurements of humidity, wind, aerosols and cloudiness in the lower atmosphere are robust and consistent with each other. They will make it possible to advance understanding of cloud–climate interactions.
Andreas Schneider, Tobias Borsdorff, Joost aan de Brugh, Alba Lorente, Franziska Aemisegger, David Noone, Dean Henze, Rigel Kivi, and Jochen Landgraf
Atmos. Meas. Tech., 15, 2251–2275, https://doi.org/10.5194/amt-15-2251-2022, https://doi.org/10.5194/amt-15-2251-2022, 2022
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This paper presents an extended H₂O/HDO total column dataset from short-wave infrared measurements by TROPOMI including cloudy and clear-sky scenes. Coverage is tremendously increased compared to previous TROPOMI HDO datasets. The new dataset is validated against recent ground-based FTIR measurements from TCCON and against aircraft measurements over the ocean. The use of the new dataset is demonstrated with a case study of a cold air outbreak in January 2020.
Carlos Alberti, Qiansi Tu, Frank Hase, Maria V. Makarova, Konstantin Gribanov, Stefani C. Foka, Vyacheslav Zakharov, Thomas Blumenstock, Michael Buchwitz, Christopher Diekmann, Benjamin Ertl, Matthias M. Frey, Hamud Kh. Imhasin, Dmitry V. Ionov, Farahnaz Khosrawi, Sergey I. Osipov, Maximilian Reuter, Matthias Schneider, and Thorsten Warneke
Atmos. Meas. Tech., 15, 2199–2229, https://doi.org/10.5194/amt-15-2199-2022, https://doi.org/10.5194/amt-15-2199-2022, 2022
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Satellite and ground-based observations at high latitudes are much sparser than at low or mid latitudes, which makes direct coincident comparisons between remote-sensing observations more difficult. Therefore, a method of scaling continuous CAMS model data to the ground-based observations is developed and used for creating virtual COCCON observations. These adjusted CAMS data are then used for satellite inter-comparison, showing good agreement in both Peterhof and Yekaterinburg cities.
Edgar Dolores-Tesillos, Franziska Teubler, and Stephan Pfahl
Weather Clim. Dynam., 3, 429–448, https://doi.org/10.5194/wcd-3-429-2022, https://doi.org/10.5194/wcd-3-429-2022, 2022
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Strong winds caused by extratropical cyclones represent a costly hazard for European countries. Here, based on CESM-LENS coupled climate simulations, we show that future changes of such strong winds are characterized by an increased magnitude and extended footprint southeast of the cyclone center. This intensification is related to a combination of increased diabatic heating and changes in upper-level wave dynamics.
Philipp Zschenderlein and Heini Wernli
Weather Clim. Dynam., 3, 391–411, https://doi.org/10.5194/wcd-3-391-2022, https://doi.org/10.5194/wcd-3-391-2022, 2022
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Precipitation and temperature are two of the most important variables describing our weather and climate. The relationship between these variables has been studied extensively; however, the role of specific weather systems in shaping this relationship has not been analysed yet. We therefore analyse whether intense precipitation occurs on warmer or on colder days and identify the relevant weather systems. In general, weather systems strongly influence this relationship, especially in winter.
Lisa-Ann Kautz, Olivia Martius, Stephan Pfahl, Joaquim G. Pinto, Alexandre M. Ramos, Pedro M. Sousa, and Tim Woollings
Weather Clim. Dynam., 3, 305–336, https://doi.org/10.5194/wcd-3-305-2022, https://doi.org/10.5194/wcd-3-305-2022, 2022
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Atmospheric blocking is associated with stationary, self-sustaining and long-lasting high-pressure systems. They can cause or at least influence surface weather extremes, such as heat waves, cold spells, heavy precipitation events, droughts or wind extremes. The location of the blocking determines where and what type of extreme event will occur. These relationships are also important for weather prediction and may change due to global warming.
Jan Clemens, Felix Ploeger, Paul Konopka, Raphael Portmann, Michael Sprenger, and Heini Wernli
Atmos. Chem. Phys., 22, 3841–3860, https://doi.org/10.5194/acp-22-3841-2022, https://doi.org/10.5194/acp-22-3841-2022, 2022
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Highly polluted air flows from the surface to higher levels of the atmosphere during the Asian summer monsoon. At high levels, the air is trapped within eddies. Here, we study how air masses can leave the eddy within its cutoff, how they distribute, and how their chemical composition changes. We found evidence for transport from the eddy to higher latitudes over the North Pacific and even Alaska. During transport, trace gas concentrations within cutoffs changed gradually, showing steady mixing.
Adrien Deroubaix, Laurent Menut, Cyrille Flamant, Peter Knippertz, Andreas H. Fink, Anneke Batenburg, Joel Brito, Cyrielle Denjean, Cheikh Dione, Régis Dupuy, Valerian Hahn, Norbert Kalthoff, Fabienne Lohou, Alfons Schwarzenboeck, Guillaume Siour, Paolo Tuccella, and Christiane Voigt
Atmos. Chem. Phys., 22, 3251–3273, https://doi.org/10.5194/acp-22-3251-2022, https://doi.org/10.5194/acp-22-3251-2022, 2022
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During the summer monsoon in West Africa, pollutants emitted in urbanized areas modify cloud cover and precipitation patterns. We analyze these patterns with the WRF-CHIMERE model, integrating the effects of aerosols on meteorology, based on the numerous observations provided by the Dynamics-Aerosol-Climate-Interactions campaign. This study adds evidence to recent findings that increased pollution levels in West Africa delay the breakup time of low-level clouds and reduce precipitation.
Matthias Schneider, Benjamin Ertl, Christopher J. Diekmann, Farahnaz Khosrawi, Andreas Weber, Frank Hase, Michael Höpfner, Omaira E. García, Eliezer Sepúlveda, and Douglas Kinnison
Earth Syst. Sci. Data, 14, 709–742, https://doi.org/10.5194/essd-14-709-2022, https://doi.org/10.5194/essd-14-709-2022, 2022
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We present atmospheric H2O, HDO / H2O ratio, N2O, CH4, and HNO3 data generated by the MUSICA IASI processor using thermal nadir spectra measured by the IASI satellite instrument. The data have global daily coverage and are available for the period between October 2014 and June 2021. Multiple possibilities of data reuse are offered by providing each individual data product together with information about retrieval settings and the products' uncertainty and vertical representativeness.
Thomas E. Taylor, Christopher W. O'Dell, David Crisp, Akhiko Kuze, Hannakaisa Lindqvist, Paul O. Wennberg, Abhishek Chatterjee, Michael Gunson, Annmarie Eldering, Brendan Fisher, Matthäus Kiel, Robert R. Nelson, Aronne Merrelli, Greg Osterman, Frédéric Chevallier, Paul I. Palmer, Liang Feng, Nicholas M. Deutscher, Manvendra K. Dubey, Dietrich G. Feist, Omaira E. García, David W. T. Griffith, Frank Hase, Laura T. Iraci, Rigel Kivi, Cheng Liu, Martine De Mazière, Isamu Morino, Justus Notholt, Young-Suk Oh, Hirofumi Ohyama, David F. Pollard, Markus Rettinger, Matthias Schneider, Coleen M. Roehl, Mahesh Kumar Sha, Kei Shiomi, Kimberly Strong, Ralf Sussmann, Yao Té, Voltaire A. Velazco, Mihalis Vrekoussis, Thorsten Warneke, and Debra Wunch
Earth Syst. Sci. Data, 14, 325–360, https://doi.org/10.5194/essd-14-325-2022, https://doi.org/10.5194/essd-14-325-2022, 2022
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We provide an analysis of an 11-year record of atmospheric carbon dioxide (CO2) concentrations derived using an optimal estimation retrieval algorithm on measurements made by the GOSAT satellite. The new product (version 9) shows improvement over the previous version (v7.3) as evaluated against independent estimates of CO2 from ground-based sensors and atmospheric inversion systems. We also compare the new GOSAT CO2 values to collocated estimates from NASA's Orbiting Carbon Observatory-2.
Katharina Hartmuth, Maxi Boettcher, Heini Wernli, and Lukas Papritz
Weather Clim. Dynam., 3, 89–111, https://doi.org/10.5194/wcd-3-89-2022, https://doi.org/10.5194/wcd-3-89-2022, 2022
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In this study, we introduce a novel method to objectively define and identify extreme Arctic seasons based on different surface variables. We find that such seasons are resulting from various combinations of unusual seasonal conditions. The occurrence or absence of different atmospheric processes strongly affects the character of extreme Arctic seasons. Further, changes in sea ice and sea surface temperature can strongly influence the formation of such a season in distinct regions.
Stephan Krätschmer, Michèlle van der Does, Frank Lamy, Gerrit Lohmann, Christoph Völker, and Martin Werner
Clim. Past, 18, 67–87, https://doi.org/10.5194/cp-18-67-2022, https://doi.org/10.5194/cp-18-67-2022, 2022
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We use an atmospheric model coupled to an aerosol model to investigate the global mineral dust cycle with a focus on the Southern Hemisphere for warmer and colder climate states and compare our results to observational data. Our findings suggest that Australia is the predominant source of dust deposited over Antarctica during the last glacial maximum. In addition, we find that the southward transport of dust from all sources to Antarctica happens at lower altitudes in colder climates.
Leonie Villiger, Heini Wernli, Maxi Boettcher, Martin Hagen, and Franziska Aemisegger
Weather Clim. Dynam., 3, 59–88, https://doi.org/10.5194/wcd-3-59-2022, https://doi.org/10.5194/wcd-3-59-2022, 2022
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The coupling between the large-scale atmospheric circulation and the clouds in the trade-wind region is complex and not yet fully understood. In this study, the formation pathway of two anomalous cloud layers over Barbados during the field campaign EUREC4A is described. The two case studies highlight the influence of remote weather systems on the local environmental conditions in Barbados.
Qiansi Tu, Frank Hase, Matthias Schneider, Omaira García, Thomas Blumenstock, Tobias Borsdorff, Matthias Frey, Farahnaz Khosrawi, Alba Lorente, Carlos Alberti, Juan J. Bustos, André Butz, Virgilio Carreño, Emilio Cuevas, Roger Curcoll, Christopher J. Diekmann, Darko Dubravica, Benjamin Ertl, Carme Estruch, Sergio Fabián León-Luis, Carlos Marrero, Josep-Anton Morgui, Ramón Ramos, Christian Scharun, Carsten Schneider, Eliezer Sepúlveda, Carlos Toledano, and Carlos Torres
Atmos. Chem. Phys., 22, 295–317, https://doi.org/10.5194/acp-22-295-2022, https://doi.org/10.5194/acp-22-295-2022, 2022
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We use different methane ground- and space-based remote sensing data sets for investigating the emission strength of three waste disposal sites close to Madrid. We present a method that uses wind-assigned anomalies for deriving emission strengths from satellite data and estimate their uncertainty to 9–14 %. The emission strengths estimated from the remote sensing data sets are significantly larger than the values published in the official register.
Philipp Zschenderlein and Heini Wernli
Nat. Hazards Earth Syst. Sci. Discuss., https://doi.org/10.5194/nhess-2021-396, https://doi.org/10.5194/nhess-2021-396, 2022
Preprint withdrawn
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In early January 2021, Spain was affected by two extreme events – an unusually long cold spell and a heavy snowfall event associated with extratropical cyclone Filomena. In the study, we analyse the synoptic-dynamic development of the two extreme events. Cold air from the north was advected towards Spain and between 07 and 10 January, cyclone Filomena was responsible for major parts of the snowfall event. During this event, temperature and moisture contrasts accross Spain were very high.
Christopher J. Diekmann, Matthias Schneider, Benjamin Ertl, Frank Hase, Omaira García, Farahnaz Khosrawi, Eliezer Sepúlveda, Peter Knippertz, and Peter Braesicke
Earth Syst. Sci. Data, 13, 5273–5292, https://doi.org/10.5194/essd-13-5273-2021, https://doi.org/10.5194/essd-13-5273-2021, 2021
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The joint analysis of different stable water isotopes in water vapour is a powerful tool for investigating atmospheric moisture pathways. This paper presents a novel global and multi-annual dataset of H2O and HDO in mid-tropospheric water vapour by using data from the satellite sensor Metop/IASI. Due to its unique combination of coverage and resolution in space and time, this dataset is highly promising for studying the hydrological cycle and its representation in weather and climate models.
Roman Attinger, Elisa Spreitzer, Maxi Boettcher, Heini Wernli, and Hanna Joos
Weather Clim. Dynam., 2, 1073–1091, https://doi.org/10.5194/wcd-2-1073-2021, https://doi.org/10.5194/wcd-2-1073-2021, 2021
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Diabatic processes affect the development of extratropical cyclones. This work provides a systematic assessment of the diabatic processes that modify potential vorticity (PV) in model simulations. PV is primarily produced by condensation and convection. Given favorable environmental conditions, long-wave radiative cooling and turbulence become the primary process at the cold and warm fronts, respectively. Turbulence and long-wave radiative heating produce negative PV anomalies at the fronts.
Cited articles
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Short summary
We use high-resolution numerical isotope modelling and Lagrangian backward trajectories to identify moisture transport pathways and governing physical and dynamical processes that affect the free-tropospheric humidity and isotopic variability over the eastern subtropical North Atlantic. Furthermore, we conduct a thorough isotope modelling validation with aircraft and remote-sensing observations of water vapour isotopes.
We use high-resolution numerical isotope modelling and Lagrangian backward trajectories to...
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