Articles | Volume 2, issue 1
https://doi.org/10.5194/wcd-2-71-2021
© 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/wcd-2-71-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
01 Feb 2021
Research article |
| 01 Feb 2021
| 01 Feb 2021
Extreme wet seasons – their definition and relationship with synoptic-scale weather systems
Emmanouil Flaounas
CORRESPONDING AUTHOR
Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland
Matthias Röthlisberger
Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland
Maxi Boettcher
Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland
Michael Sprenger
Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland
Heini Wernli
Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland
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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.
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This study explores extreme marine summers (EMSs) in the Mediterranean Sea using sea surface temperature (SST) data. EMSs arise mainly due to the warmest summer days being unusually warm. Air–sea heat fluxes drive EMSs in northern regions, where also enhanced marine heatwave conditions are found during EMSs. Long-term SST changes lead to warmer EMSs while not affecting the way daily SST values are organized during EMSs. Findings enhance comprehension of anomalously warm conditions in the basin.
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A novel classification of Mediterranean cyclones is presented, enabling a separation between storms driven by different atmospheric processes. The surface impact of each cyclone class differs greatly by precipitation, winds, and temperatures, providing an invaluable tool to study the climatology of different types of Mediterranean storms and enhancing the understanding of their predictability, on both weather and climate scales.
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Emmanouil Flaounas, Vassiliki Kotroni, Konstantinos Lagouvardos, Martina Klose, Cyrille Flamant, and Theodore M. Giannaros
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Revised manuscript not accepted
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Using an innovative approach, the descent of foehn is diagnosed from a Lagrangian perspective based on 15 kilometer-scale simulations combined with online trajectories. The descent is confined to distinct hotspots in the immediate lee of local mountain peaks and chains. Two detailed case studies reveal a varying wave regime to be associated with the descent. Furthermore, additional controlling factors, such as the diurnal cycle, likewise influence the descent activity.
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Ocean Sci., 20, 433–461, https://doi.org/10.5194/os-20-433-2024, https://doi.org/10.5194/os-20-433-2024, 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.
Hilla Afargan-Gerstman, Dominik Büeler, C. Ole Wulff, Michael Sprenger, and Daniela I. V. Domeisen
Weather Clim. Dynam., 5, 231–249, https://doi.org/10.5194/wcd-5-231-2024, https://doi.org/10.5194/wcd-5-231-2024, 2024
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The stratosphere is a layer of Earth's atmosphere found above the weather systems. Changes in the stratosphere can affect the winds and the storm tracks in the North Atlantic region for a relatively long time, lasting for several weeks and even months. We show that the stratosphere can be important for weather forecasts beyond 1 week, but more work is needed to improve the accuracy of these forecasts for 3–4 weeks.
Yonatan Givon, Or Hess, Emmanouil Flaounas, Jennifer Louise Catto, Michael Sprenger, and Shira Raveh-Rubin
Weather Clim. Dynam., 5, 133–162, https://doi.org/10.5194/wcd-5-133-2024, https://doi.org/10.5194/wcd-5-133-2024, 2024
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A novel classification of Mediterranean cyclones is presented, enabling a separation between storms driven by different atmospheric processes. The surface impact of each cyclone class differs greatly by precipitation, winds, and temperatures, providing an invaluable tool to study the climatology of different types of Mediterranean storms and enhancing the understanding of their predictability, on both weather and climate scales.
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.
Sebastian Schemm and Matthias Röthlisberger
Weather Clim. Dynam., 5, 43–63, https://doi.org/10.5194/wcd-5-43-2024, https://doi.org/10.5194/wcd-5-43-2024, 2024
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Climate change has started to weaken atmospheric circulation during summer in the Northern Hemisphere. However, there is low agreement on the processes underlying changes in, for example, the stationarity of weather patterns or the seasonality of the jet response to warming. This study examines changes during summertime in an idealised setting and confirms some important changes in hemisphere-wide wave and jet characteristics under warming.
Stefania Gilardoni, Dominic Heslin-Rees, Mauro Mazzola, Vito Vitale, Michael Sprenger, and Radovan Krejci
Atmos. Chem. Phys., 23, 15589–15607, https://doi.org/10.5194/acp-23-15589-2023, https://doi.org/10.5194/acp-23-15589-2023, 2023
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Models still fail in reproducing black carbon (BC) temporal variability in the Arctic. Analysis of equivalent BC concentrations in the European Arctic shows that BC seasonal variability is modulated by the efficiency of removal by precipitation during transport towards high latitudes. Short-term variability is controlled by synoptic-scale circulation patterns. The advection of warm air from lower latitudes is an effective pollution transport pathway during summer.
Ellina Agayar, Franziska Aemisegger, Moshe Armon, Alexander Scherrmann, and Heini Wernli
EGUsphere, https://doi.org/10.5194/egusphere-2023-2594, https://doi.org/10.5194/egusphere-2023-2594, 2023
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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 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 synoptical analysis.
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.
Heini Wernli and Suzanne L. Gray
EGUsphere, https://doi.org/10.5194/egusphere-2023-2678, https://doi.org/10.5194/egusphere-2023-2678, 2023
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This review provides a historic overview of research on how diabatic processes influence extratropical weather systems. We highlight that the combination of complementary research approaches – field experiments, diagnostics, numerical model experiments, potential vorticity theory, and consideration of climate change – was essential for reaching a new level of understanding where the interplay of dry dynamics with diabatic processes is considered as central to the field.
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.
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.
Melanie Lauer, Annette Rinke, Irina Gorodetskaya, Michael Sprenger, Mario Mech, and Susanne Crewell
Atmos. Chem. Phys., 23, 8705–8726, https://doi.org/10.5194/acp-23-8705-2023, https://doi.org/10.5194/acp-23-8705-2023, 2023
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We present a new method to analyse the influence of atmospheric rivers (ARs), cyclones, and fronts on the precipitation in the Arctic, based on two campaigns: ACLOUD (early summer 2017) and AFLUX (early spring 2019). There are differences between both campaign periods: in early summer, the precipitation is mostly related to ARs and fronts, especially when they are co-located, while in early spring, cyclones isolated from ARs and fronts contributed most to the precipitation.
Emmanouil Flaounas, Leonardo Aragão, Lisa Bernini, Stavros Dafis, Benjamin Doiteau, Helena Flocas, Suzanne L. Gray, Alexia Karwat, John Kouroutzoglou, Piero Lionello, Mario Marcello Miglietta, Florian Pantillon, Claudia Pasquero, Platon Patlakas, María Ángeles Picornell, Federico Porcù, Matthew D. K. Priestley, Marco Reale, Malcolm J. Roberts, Hadas Saaroni, Dor Sandler, Enrico Scoccimarro, Michael Sprenger, and Baruch Ziv
Weather Clim. Dynam., 4, 639–661, https://doi.org/10.5194/wcd-4-639-2023, https://doi.org/10.5194/wcd-4-639-2023, 2023
Short summary
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Cyclone detection and tracking methods (CDTMs) have different approaches in defining and tracking cyclone centers. This leads to disagreements on extratropical cyclone climatologies. We present a new approach that combines tracks from individual CDTMs to produce new composite tracks. These new tracks are shown to correspond to physically meaningful systems with distinctive life stages.
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.
Christian Ferrarin, Florian Pantillon, Silvio Davolio, Marco Bajo, Mario Marcello Miglietta, Elenio Avolio, Diego S. Carrió, Ioannis Pytharoulis, Claudio Sanchez, Platon Patlakas, Juan Jesús González-Alemán, and Emmanouil Flaounas
Nat. Hazards Earth Syst. Sci., 23, 2273–2287, https://doi.org/10.5194/nhess-23-2273-2023, https://doi.org/10.5194/nhess-23-2273-2023, 2023
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The combined use of meteorological and ocean models enabled the analysis of extreme sea conditions driven by Medicane Ianos, which hit the western coast of Greece on 18 September 2020, flooding and damaging the coast. The large spread associated with the ensemble highlighted the high model uncertainty in simulating such an extreme weather event. The different simulations have been used for outlining hazard scenarios that represent a fundamental component of the coastal risk assessment.
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.
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.
Michael A. Barnes, Thando Ndarana, Michael Sprenger, and Willem A. Landman
Weather Clim. Dynam., 3, 1291–1309, https://doi.org/10.5194/wcd-3-1291-2022, https://doi.org/10.5194/wcd-3-1291-2022, 2022
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Stratospheric air can intrude into the troposphere and is associated with cyclonic development throughout the atmosphere. Through a highly idealized systematic approach, the effect that different intrusion characteristics have on surface cyclogenetic forcing is investigated. The proximity of stratospheric intrusions to the surface is shown to be the main factor in surface cyclogenetic forcing, whilst its width is an additional contributing factor.
S. Mubashshir Ali, Matthias Röthlisberger, Tess Parker, Kai Kornhuber, and Olivia Martius
Weather Clim. Dynam., 3, 1139–1156, https://doi.org/10.5194/wcd-3-1139-2022, https://doi.org/10.5194/wcd-3-1139-2022, 2022
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Persistent weather can lead to extreme weather conditions. One such atmospheric flow pattern, termed recurrent Rossby wave packets (RRWPs), has been shown to increase persistent weather in the Northern Hemisphere. Here, we show that RRWPs are also an important feature in the Southern Hemisphere. We evaluate the role of RRWPs during south-eastern Australian heatwaves and find that they help to persist the heatwaves by forming upper-level high-pressure systems over south-eastern Australia.
Lukas Jansing, Lukas Papritz, Bruno Dürr, Daniel Gerstgrasser, and Michael Sprenger
Weather Clim. Dynam., 3, 1113–1138, https://doi.org/10.5194/wcd-3-1113-2022, https://doi.org/10.5194/wcd-3-1113-2022, 2022
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This study presents a 5-year climatology of three main foehn types and three deep-foehn subtypes. The main types differ in their large-scale and Alpine-scale weather conditions and the subtypes in terms of the amount and extent of precipitation on the Alpine south side. The different types of foehn are found to strongly affect the local meteorological conditions at Altdorf. The study concludes by setting the new classification into a historic context.
Matthias Röthlisberger, Barbara Scherrer, Andries Jan de Vries, and Raphael Portmann
Weather Clim. Dynam., 3, 733–754, https://doi.org/10.5194/wcd-3-733-2022, https://doi.org/10.5194/wcd-3-733-2022, 2022
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We examine the palette of synoptic storylines accompanying unusually long wet spells in Europe. Thereby, we identify a hitherto not documented mechanism for generating long wet spells which involves recurrent Rossby wave breaking and subsequent cutoff replenishment. Understanding the synoptic processes behind long wet spells is relevant in light of projected changes in wet spell characteristics as it is a prerequisite for evaluating climate models with regard to such events.
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.
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.
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.
Jörg Wieder, Claudia Mignani, Mario Schär, Lucie Roth, Michael Sprenger, Jan Henneberger, Ulrike Lohmann, Cyril Brunner, and Zamin A. Kanji
Atmos. Chem. Phys., 22, 3111–3130, https://doi.org/10.5194/acp-22-3111-2022, https://doi.org/10.5194/acp-22-3111-2022, 2022
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We investigate the variation in ice-nucleating particles (INPs) relevant for primary ice formation in mixed-phased clouds over the Alps based on simultaneous in situ observations at a mountaintop and a nearby high valley (1060 m height difference). In most cases, advection from the surrounding lower regions was responsible for changes in INP concentration, causing a diurnal cycle at the mountaintop. Our study underlines the importance of the planetary boundary layer as an INP reserve.
Emmanouil Flaounas, Silvio Davolio, Shira Raveh-Rubin, Florian Pantillon, Mario Marcello Miglietta, Miguel Angel Gaertner, Maria Hatzaki, Victor Homar, Samira Khodayar, Gerasimos Korres, Vassiliki Kotroni, Jonilda Kushta, Marco Reale, and Didier Ricard
Weather Clim. Dynam., 3, 173–208, https://doi.org/10.5194/wcd-3-173-2022, https://doi.org/10.5194/wcd-3-173-2022, 2022
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This is a collective effort to describe the state of the art in Mediterranean cyclone dynamics, climatology, prediction (weather and climate scales) and impacts. More than that, the paper focuses on the future directions of research that would advance the broader field of Mediterranean cyclones as a whole. Thereby, we propose interdisciplinary cooperation and additional modelling and forecasting strategies, and we highlight the need for new impact-oriented approaches to climate prediction.
Lukas Bösiger, Michael Sprenger, Maxi Boettcher, Hanna Joos, and Tobias Günther
Geosci. Model Dev., 15, 1079–1096, https://doi.org/10.5194/gmd-15-1079-2022, https://doi.org/10.5194/gmd-15-1079-2022, 2022
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Jet streams are coherent air flows that interact with atmospheric structures such as warm conveyor belts (WCBs) and the tropopause. Individually, these structures have a significant impact on the weather evolution. A first step towards a deeper understanding of the meteorological processes is to extract jet stream core lines, for which we develop a novel feature extraction algorithm. Based on the line geometry, we automatically detect and visualize potential interactions between WCBs and jets.
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.
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.
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.
Samira Khodayar, Silvio Davolio, Paolo Di Girolamo, Cindy Lebeaupin Brossier, Emmanouil Flaounas, Nadia Fourrie, Keun-Ok Lee, Didier Ricard, Benoit Vie, Francois Bouttier, Alberto Caldas-Alvarez, and Veronique Ducrocq
Atmos. Chem. Phys., 21, 17051–17078, https://doi.org/10.5194/acp-21-17051-2021, https://doi.org/10.5194/acp-21-17051-2021, 2021
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Heavy precipitation (HP) constitutes a major meteorological threat in the western Mediterranean. Every year, recurrent events affect the area with fatal consequences. Despite this being a well-known issue, open questions still remain. The understanding of the underlying mechanisms and the modeling representation of the events must be improved. In this article we present the most recent lessons learned from the Hydrological Cycle in the Mediterranean Experiment (HyMeX).
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.
Fabienne Dahinden, Franziska Aemisegger, Heini Wernli, Matthias Schneider, Christopher J. Diekmann, Benjamin Ertl, Peter Knippertz, Martin Werner, and Stephan Pfahl
Atmos. Chem. Phys., 21, 16319–16347, https://doi.org/10.5194/acp-21-16319-2021, https://doi.org/10.5194/acp-21-16319-2021, 2021
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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.
Philippe Besson, Luise J. Fischer, Sebastian Schemm, and Michael Sprenger
Weather Clim. Dynam., 2, 991–1009, https://doi.org/10.5194/wcd-2-991-2021, https://doi.org/10.5194/wcd-2-991-2021, 2021
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The strongest cyclone intensification is associated with a strong dry-dynamical forcing. Moreover, strong forcing and strong intensification correspond to a tendency for poleward cyclone propagation, which occurs in distinct regions in the Northern Hemisphere. There is a clear spatial pattern in the occurrence of certain forcing combinations. This implies a fundamental relationship between dry-dynamical processes and the intensification as well as the propagation of extratropical cyclones.
Raphael Portmann, Michael Sprenger, and Heini Wernli
Weather Clim. Dynam., 2, 507–534, https://doi.org/10.5194/wcd-2-507-2021, https://doi.org/10.5194/wcd-2-507-2021, 2021
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We explore the three-dimensional life cycle of cyclonic structures
(so-called PV cutoffs) near the tropopause. PV cutoffs are frequent weather systems in the extratropics that lead to high-impact weather. However, many unknowns exist regarding their evolution. We present a new method to track PV cutoffs as 3D objects in reanalysis data by following air parcels along the flow. We study the climatological life cycles of PV cutoffs in detail and propose a classification into three types.
Iris Thurnherr, Katharina Hartmuth, Lukas Jansing, Josué Gehring, Maxi Boettcher, Irina Gorodetskaya, Martin Werner, Heini Wernli, and Franziska Aemisegger
Weather Clim. Dynam., 2, 331–357, https://doi.org/10.5194/wcd-2-331-2021, https://doi.org/10.5194/wcd-2-331-2021, 2021
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Extratropical cyclones are important for the transport of moisture from low to high latitudes. In this study, we investigate how the isotopic composition of water vapour is affected by horizontal temperature advection associated with extratropical cyclones using measurements and modelling. It is shown that air–sea moisture fluxes induced by this horizontal temperature advection lead to the strong variability observed in the isotopic composition of water vapour in the marine boundary layer.
Maxi Boettcher, Andreas Schäfler, Michael Sprenger, Harald Sodemann, Stefan Kaufmann, Christiane Voigt, Hans Schlager, Donato Summa, Paolo Di Girolamo, Daniele Nerini, Urs Germann, and Heini Wernli
Atmos. Chem. Phys., 21, 5477–5498, https://doi.org/10.5194/acp-21-5477-2021, https://doi.org/10.5194/acp-21-5477-2021, 2021
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Warm conveyor belts (WCBs) are important airstreams in extratropical cyclones, often leading to the formation of intense precipitation. We present a case study that involves aircraft, lidar and radar observations of water and clouds in a WCB ascending from western Europe across the Alps towards the Baltic Sea during the field campaigns HyMeX and T-NAWDEX-Falcon in October 2012. A probabilistic trajectory measure and an airborne tracer experiment were used to confirm the long pathway of the WCB.
Emmanouil Flaounas, Suzanne L. Gray, and Franziska Teubler
Weather Clim. Dynam., 2, 255–279, https://doi.org/10.5194/wcd-2-255-2021, https://doi.org/10.5194/wcd-2-255-2021, 2021
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In this study, we quantify the relative contribution of different atmospheric processes to the development of 100 intense Mediterranean cyclones and show that both upper tropospheric systems and diabatic processes contribute to cyclone development. However, these contributions are complex and present high variability among the cases. For this reason, we analyse several exemplary cases in more detail, including 10 systems that have been identified in the past as tropical-like cyclones.
Franziska Aemisegger, Raphaela Vogel, Pascal Graf, Fabienne Dahinden, Leonie Villiger, Friedhelm Jansen, Sandrine Bony, Bjorn Stevens, and Heini Wernli
Weather Clim. Dynam., 2, 281–309, https://doi.org/10.5194/wcd-2-281-2021, https://doi.org/10.5194/wcd-2-281-2021, 2021
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The interaction of clouds in the trade wind region with the atmospheric flow is complex and at the heart of uncertainties associated with climate projections. In this study, a natural tracer of atmospheric circulation is used to establish a link between air originating from dry regions of the midlatitudes and the occurrence of specific cloud patterns. Two pathways involving transport within midlatitude weather systems are identified, by which air is brought into the trades within 5–10 d.
Melissa L. Breeden, Amy H. Butler, John R. Albers, Michael Sprenger, and Andrew O'Neil Langford
Atmos. Chem. Phys., 21, 2781–2794, https://doi.org/10.5194/acp-21-2781-2021, https://doi.org/10.5194/acp-21-2781-2021, 2021
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Prior research has found a maximum in deep stratosphere-to-troposphere mass/ozone transport over the western United States in boreal spring, which can enhance surface ozone concentrations, reducing air quality. We find that the winter-to-summer evolution of the north Pacific jet increases the frequency of stratospheric intrusions that drive transport, helping explain the observed maximum. The El Niño–Southern Oscillation affects the timing of the spring jet transition and therefore transport.
Annika Oertel, Michael Sprenger, Hanna Joos, Maxi Boettcher, Heike Konow, Martin Hagen, and Heini Wernli
Weather Clim. Dynam., 2, 89–110, https://doi.org/10.5194/wcd-2-89-2021, https://doi.org/10.5194/wcd-2-89-2021, 2021
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Convection embedded in the stratiform cloud band of strongly ascending airstreams in extratropical cyclones (so-called warm conveyor belts) can influence not only surface precipitation but also the
upper-tropospheric potential vorticity (PV) and waveguide. The comparison of intense vs. moderate embedded convection shows that its strength alone is not a reliable measure for upper-tropospheric PV modification. Instead, characteristics of the ambient flow co-determine its dynamical significance.
Sebastian Schemm, Heini Wernli, and Hanin Binder
Weather Clim. Dynam., 2, 55–69, https://doi.org/10.5194/wcd-2-55-2021, https://doi.org/10.5194/wcd-2-55-2021, 2021
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North Pacific cyclone intensities are reduced in winter, which is in contrast to North Atlantic cyclones and unexpected from the high available growth potential in winter. We investigate this intensity suppression from a cyclone life-cycle perspective and show that in winter Kuroshio cyclones propagate away from the region where they can grow more quickly, East China Sea cyclones are not relevant before spring, and Kamchatka cyclones grow in a region of reduced growth potential.
Claudia Mignani, Jörg Wieder, Michael A. Sprenger, Zamin A. Kanji, Jan Henneberger, Christine Alewell, and Franz Conen
Atmos. Chem. Phys., 21, 657–664, https://doi.org/10.5194/acp-21-657-2021, https://doi.org/10.5194/acp-21-657-2021, 2021
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Most precipitation above land starts with ice in clouds. It is promoted by extremely rare particles. Some ice-nucleating particles (INPs) cause cloud droplets to already freeze above −15°C, a temperature at which many clouds begin to snow. We found that the abundance of such INPs among other particles of similar size is highest in precipitating air masses and lowest when air carries desert dust. This brings us closer to understanding the interactions between land, clouds, and precipitation.
Stefan Rüdisühli, Michael Sprenger, David Leutwyler, Christoph Schär, and Heini Wernli
Weather Clim. Dynam., 1, 675–699, https://doi.org/10.5194/wcd-1-675-2020, https://doi.org/10.5194/wcd-1-675-2020, 2020
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Most precipitation over Europe is linked to low-pressure systems, cold fronts, warm fronts, or high-pressure systems. Based on a massive computer simulation able to resolve thunderstorms, we quantify in detail how much precipitation these weather systems produced during 2000–2008. We find distinct seasonal and regional differences, such as fronts precipitating a lot in fall and winter over the North Atlantic but high-pressure systems mostly in summer over the continent by way of thunderstorms.
Raphael Portmann, Juan Jesús González-Alemán, Michael Sprenger, and Heini Wernli
Weather Clim. Dynam., 1, 597–615, https://doi.org/10.5194/wcd-1-597-2020, https://doi.org/10.5194/wcd-1-597-2020, 2020
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In September 2018 an intense Mediterranean cyclone with structural similarities to a hurricane, a so-called medicane, caused severe damage in Greece. Its development was uncertain, even just a few days in advance. The reason for this was uncertainties in the jet stream over the North Atlantic 3 d prior to cyclogenesis that propagated into the Mediterranean. They led to an uncertain position of the upper-level disturbance and, as a result, of the position and thermal structure of the cyclone.
Hanin Binder, Maxi Boettcher, Hanna Joos, Michael Sprenger, and Heini Wernli
Weather Clim. Dynam., 1, 577–595, https://doi.org/10.5194/wcd-1-577-2020, https://doi.org/10.5194/wcd-1-577-2020, 2020
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Warm conveyor belts (WCBs) are important cloud- and
precipitation-producing airstreams in extratropical cyclones. By combining satellite observations with model data from a new reanalysis dataset, this study provides detailed observational insight into the vertical cloud structure of WCBs. We find that the reanalyses essentially capture the observed cloud pattern, but the observations reveal mesoscale structures not resolved by the temporally and spatially much coarser-resolution model data.
Mauro Hermann, Lukas Papritz, and Heini Wernli
Weather Clim. Dynam., 1, 497–518, https://doi.org/10.5194/wcd-1-497-2020, https://doi.org/10.5194/wcd-1-497-2020, 2020
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We find, by tracing backward in time, that air masses causing extensive melt of the Greenland Ice Sheet originate from further south and lower altitudes than usual. Their exceptional warmth further arises due to ascent and cloud formation, which is special compared to near-surface heat waves in the midlatitudes or the central Arctic. The atmospheric systems and transport pathways identified here are crucial in understanding and simulating the atmospheric control of the ice sheet in the future.
Sebastian Schemm, Stefan Rüdisühli, and Michael Sprenger
Weather Clim. Dynam., 1, 459–479, https://doi.org/10.5194/wcd-1-459-2020, https://doi.org/10.5194/wcd-1-459-2020, 2020
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Troughs and ridges are ubiquitous flow features in the upper troposphere and are centerpiece elements of weather and climate research. A novel method is introduced to identify and track the life cycle of troughs and ridges and their orientation. The aim is to close the existing gap between methods that detect the initiation phase and methods that detect the decaying phase of Rossby wave development. Global climatologies, the influence of ENSO and Lagrangian characteristics are discussed.
Daniel Steinfeld, Maxi Boettcher, Richard Forbes, and Stephan Pfahl
Weather Clim. Dynam., 1, 405–426, https://doi.org/10.5194/wcd-1-405-2020, https://doi.org/10.5194/wcd-1-405-2020, 2020
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The effect of latent heating on atmospheric blocking is investigated using numerical sensitivity experiments. The modification of latent heating in the upstream cyclone has substantial effects on the upper-tropospheric circulation, demonstrating that some blocking systems do not develop at all without upstream latent heating. The results highlight the importance of moist-diabatic processes for the dynamics of prolonged anticyclonic circulation anomalies.
Nicolas Jullien, Étienne Vignon, Michael Sprenger, Franziska Aemisegger, and Alexis Berne
The Cryosphere, 14, 1685–1702, https://doi.org/10.5194/tc-14-1685-2020, https://doi.org/10.5194/tc-14-1685-2020, 2020
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Although snowfall is the main input of water to the Antarctic ice sheet, snowflakes are often evaporated by dry and fierce winds near the surface of the continent. The amount of snow that actually reaches the ground is therefore considerably reduced. By analyzing the position of cyclones and fronts as well as by back-tracing the atmospheric moisture pathway towards Antarctica, this study explains in which meteorological conditions snowfall is either completely evaporated or reaches the ground.
Iris Thurnherr, Anna Kozachek, Pascal Graf, Yongbiao Weng, Dimitri Bolshiyanov, Sebastian Landwehr, Stephan Pfahl, Julia Schmale, Harald Sodemann, Hans Christian Steen-Larsen, Alessandro Toffoli, Heini Wernli, and Franziska Aemisegger
Atmos. Chem. Phys., 20, 5811–5835, https://doi.org/10.5194/acp-20-5811-2020, https://doi.org/10.5194/acp-20-5811-2020, 2020
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Stable water isotopes (SWIs) are tracers of moist atmospheric processes. We analyse the impact of large- to small-scale atmospheric processes and various environmental conditions on the variability of SWIs using ship-based SWI measurement in water vapour from the Atlantic and Southern Ocean. Furthermore, simultaneous measurements of SWIs at two altitudes are used to illustrate the potential of such measurements for future research to estimate sea spray evaporation and turbulent moisture fluxes.
Philipp Zschenderlein, Stephan Pfahl, Heini Wernli, and Andreas H. Fink
Weather Clim. Dynam., 1, 191–206, https://doi.org/10.5194/wcd-1-191-2020, https://doi.org/10.5194/wcd-1-191-2020, 2020
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We analyse the formation of upper-tropospheric anticyclones connected to European surface heat waves. Tracing air masses backwards from these anticyclones, we found that trajectories are diabatically heated in two branches, either by North Atlantic cyclones or by convection closer to the heat wave anticyclone. The first branch primarily affects the onset of the anticyclone, while the second branch is more relevant for the maintenance. Our results are relevant for heat wave predictions.
Annika Oertel, Maxi Boettcher, Hanna Joos, Michael Sprenger, and Heini Wernli
Weather Clim. Dynam., 1, 127–153, https://doi.org/10.5194/wcd-1-127-2020, https://doi.org/10.5194/wcd-1-127-2020, 2020
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Warm conveyor belts (WCBs) are important, mainly stratiform cloud forming airstreams in extratropical cyclones that can include embedded convection. This WCB case study systematically compares the characteristics of convective vs. slantwise ascent of the WCB. We find that embedded convection leads to regions of significantly stronger precipitation. Moreover, it strongly modifies the potential vorticity distribution in the lower and upper troposphere, where its also influences the waveguide.
Matthias Röthlisberger, Michael Sprenger, Emmanouil Flaounas, Urs Beyerle, and Heini Wernli
Weather Clim. Dynam., 1, 45–62, https://doi.org/10.5194/wcd-1-45-2020, https://doi.org/10.5194/wcd-1-45-2020, 2020
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In this study we quantify how much the coldest, middle and hottest third of all days during extremely hot summers contribute to their respective seasonal mean anomaly. This
extreme-summer substructurevaries substantially across the Northern Hemisphere and is directly related to the local physical drivers of extreme summers. Furthermore, comparing re-analysis (i.e. measurement-based) and climate model extreme-summer substructures reveals a remarkable level of agreement.
Thomas Trickl, Hannes Vogelmann, Ludwig Ries, and Michael Sprenger
Atmos. Chem. Phys., 20, 243–266, https://doi.org/10.5194/acp-20-243-2020, https://doi.org/10.5194/acp-20-243-2020, 2020
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Ozone transfer from the stratosphere to the troposphere seems to to have grown over the past decade, parallel to global warming. Lidar measurements, carried out in Garmisch-Partenkirchen, Germany, between 2007 and 2016 show a considerable stratospheric influence in the free troposphere over these sites, with observations of stratospheric layers in the troposphere on 84 % of the measurement days. This high fraction is almost reached also in North America, but frequently not throughout the year.
Bojan Škerlak, Stephan Pfahl, Michael Sprenger, and Heini Wernli
Atmos. Chem. Phys., 19, 6535–6549, https://doi.org/10.5194/acp-19-6535-2019, https://doi.org/10.5194/acp-19-6535-2019, 2019
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Upper-level fronts are often associated with the rapid transport of stratospheric air to the lower troposphere, leading to significantly enhanced ozone concentrations. This paper considers the multi-scale nature that is needed to bring stratospheric air down to the surface. The final transport step to the surface can be related to frontal zones and the associated vertical winds or to near-horizontal tracer transport followed by entrainment into a growing planetary boundary layer.
Pascal Graf, Heini Wernli, Stephan Pfahl, and Harald Sodemann
Atmos. Chem. Phys., 19, 747–765, https://doi.org/10.5194/acp-19-747-2019, https://doi.org/10.5194/acp-19-747-2019, 2019
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This article studies the interaction between falling rain and vapour with stable water isotopes. In particular, rain evaporation is relevant for several atmospheric processes, but remains difficult to quantify. A novel framework is introduced to facilitate the interpretation of stable water isotope observations in near-surface vapour and rain. The usefulness of this concept is demonstrated using observations at high time resolution from a cold front. Sensitivities are tested with a simple model.
Simone Brunamonti, Teresa Jorge, Peter Oelsner, Sreeharsha Hanumanthu, Bhupendra B. Singh, K. Ravi Kumar, Sunil Sonbawne, Susanne Meier, Deepak Singh, Frank G. Wienhold, Bei Ping Luo, Maxi Boettcher, Yann Poltera, Hannu Jauhiainen, Rijan Kayastha, Jagadishwor Karmacharya, Ruud Dirksen, Manish Naja, Markus Rex, Suvarna Fadnavis, and Thomas Peter
Atmos. Chem. Phys., 18, 15937–15957, https://doi.org/10.5194/acp-18-15937-2018, https://doi.org/10.5194/acp-18-15937-2018, 2018
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Based on balloon-borne measurements performed in India and Nepal in 2016–2017, we infer the vertical distributions of water vapor, ozone and aerosols in the atmosphere, from the surface to 30 km altitude. Our measurements show that the atmospheric dynamics of the Asian summer monsoon system over the polluted Indian subcontinent lead to increased concentrations of water vapor and aerosols in the high atmosphere (approximately 14–20 km altitude), which can have an important effect on climate.
Yulan Zhang, Shichang Kang, Michael Sprenger, Zhiyuan Cong, Tanguang Gao, Chaoliu Li, Shu Tao, Xiaofei Li, Xinyue Zhong, Min Xu, Wenjun Meng, Bigyan Neupane, Xiang Qin, and Mika Sillanpää
The Cryosphere, 12, 413–431, https://doi.org/10.5194/tc-12-413-2018, https://doi.org/10.5194/tc-12-413-2018, 2018
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Light-absorbing impurities deposited on snow can reduce surface albedo and contribute to the near-worldwide melting of snowpack and ice. This study focused on the black carbon and mineral dust in snow cover on the Tibetan Plateau. We discussed their concentrations, distributions, possible sources, and albedo reduction and radiative forcing. Findings indicated that the impacts of black carbon and mineral dust need to be properly accounted for in future regional climate projections.
Marina Dütsch, Stephan Pfahl, Miro Meyer, and Heini Wernli
Atmos. Chem. Phys., 18, 1653–1669, https://doi.org/10.5194/acp-18-1653-2018, https://doi.org/10.5194/acp-18-1653-2018, 2018
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Atmospheric processes are imprinted in the concentrations of stable water isotopes. Therefore, isotopes can be used to gain insight into these processes and improve our understanding of the water cycle. In this study, we present a new method that quantitatively shows which atmospheric processes influence isotope concentrations in near-surface water vapour over Europe. We found that the most important processes are evaporation from the ocean, evapotranspiration from land, and turbulent mixing.
Thomas Trickl, Hannes Vogelmann, Ludwig Ries, Hans-Eckhart Scheel, and Michael Sprenger
Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2017-1192, https://doi.org/10.5194/acp-2017-1192, 2018
Revised manuscript not accepted
Emmanouil Flaounas, Vassiliki Kotroni, Konstantinos Lagouvardos, Martina Klose, Cyrille Flamant, and Theodore M. Giannaros
Geosci. Model Dev., 10, 2925–2945, https://doi.org/10.5194/gmd-10-2925-2017, https://doi.org/10.5194/gmd-10-2925-2017, 2017
Hanna Joos, Erica Madonna, Kasja Witlox, Sylvaine Ferrachat, Heini Wernli, and Ulrike Lohmann
Atmos. Chem. Phys., 17, 6243–6255, https://doi.org/10.5194/acp-17-6243-2017, https://doi.org/10.5194/acp-17-6243-2017, 2017
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The influence of pollution on the precipitation formation in warm conveyor belts (WCBs), the most rising air streams in low-pressure systems is investigated. We investigate in detail the cloud properties and resulting precipitation along these rising airstreams which are simulated with a global climate model. Overall, no big impact of aerosols on precipitation can be seen, however, when comparing the most polluted/cleanest WCBs, a suppression of precipitation by aerosols is observed.
Harald Sodemann, Franziska Aemisegger, Stephan Pfahl, Mark Bitter, Ulrich Corsmeier, Thomas Feuerle, Pascal Graf, Rolf Hankers, Gregor Hsiao, Helmut Schulz, Andreas Wieser, and Heini Wernli
Atmos. Chem. Phys., 17, 6125–6151, https://doi.org/10.5194/acp-17-6125-2017, https://doi.org/10.5194/acp-17-6125-2017, 2017
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We report here the first survey of stable water isotope composition over the Mediterranean sea made from aircraft. The stable isotope composition of the atmospheric water vapour changed in response to evaporation conditions at the sea surface, elevation, and airmass transport history. Our data set will be valuable for testing how water is transported in weather prediction and climate models and for understanding processes in the Mediterranean water cycle.
Davide Putero, Paolo Cristofanelli, Michael Sprenger, Bojan Škerlak, Laura Tositti, and Paolo Bonasoni
Atmos. Chem. Phys., 16, 14203–14217, https://doi.org/10.5194/acp-16-14203-2016, https://doi.org/10.5194/acp-16-14203-2016, 2016
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The aim of this paper is to present STEFLUX, a tool to obtain a fast-computing identification of the stratospheric intrusion (SI) events occurring at a specific location and during a specified time window. STEFLUX results are compared to the SI observations at two high-mountain WMO/GAW global stations in Nepal and Italy, representative of two hot spots for climate change. Furthermore, the climatology of SI at the two stations is assessed, and the impact of several climate factors investigated.
Dimitris Akritidis, Andrea Pozzer, Prodromos Zanis, Evangelos Tyrlis, Bojan Škerlak, Michael Sprenger, and Jos Lelieveld
Atmos. Chem. Phys., 16, 14025–14039, https://doi.org/10.5194/acp-16-14025-2016, https://doi.org/10.5194/acp-16-14025-2016, 2016
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We investigate the contribution of tropopause folds in the summertime tropospheric ozone pool over the eastern Mediterranean and the Middle East. For this purpose we use the EMAC atmospheric chemistry–climate model and a fold identification algorithm. A clear increase of ozone is found in the middle troposphere due to fold activity. The interannual variability of near-surface ozone over the eastern Mediterranean is related to that of both tropopause folds and ozone in the free troposphere.
Thomas Trickl, Hannes Vogelmann, Andreas Fix, Andreas Schäfler, Martin Wirth, Bertrand Calpini, Gilbert Levrat, Gonzague Romanens, Arnoud Apituley, Keith M. Wilson, Robert Begbie, Jens Reichardt, Holger Vömel, and Michael Sprenger
Atmos. Chem. Phys., 16, 8791–8815, https://doi.org/10.5194/acp-16-8791-2016, https://doi.org/10.5194/acp-16-8791-2016, 2016
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A rather homogeneous deep stratospheric intrusion event was mapped by vertical sounding over central Europe and by model calculations along the transport path. The very low minimum H2O mixing ratios demonstrate almost negligible mixing with tropospheric air during the downward transport. The vertical distributions of O3 and aerosol were transferred from the source region to Europe without major change. A rather shallow outflow from the stratosphere was found.
Emmanouil Flaounas, Vassiliki Kotroni, Konstantinos Lagouvardos, Martina Klose, Cyrille Flamant, and Theodore M. Giannaros
Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2016-307, https://doi.org/10.5194/acp-2016-307, 2016
Revised manuscript not accepted
Florian Berkes, Peter Hoor, Heiko Bozem, Daniel Kunkel, Michael Sprenger, and Stephan Henne
Atmos. Chem. Phys., 16, 6011–6025, https://doi.org/10.5194/acp-16-6011-2016, https://doi.org/10.5194/acp-16-6011-2016, 2016
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We presented airborne measurements of CO2 and O3 across the entrainment zone over a semi-remote environment in southwestern Germany in late summer 2011 .
For the first time CO2 and O3 were used as tracer to identify mixing through this transport barrier. We demonstrated that the tracer--tracer correlation of CO2 and O3 is a powerful tool to identify entrainment and mixing.
P. Reutter, B. Škerlak, M. Sprenger, and H. Wernli
Atmos. Chem. Phys., 15, 10939–10953, https://doi.org/10.5194/acp-15-10939-2015, https://doi.org/10.5194/acp-15-10939-2015, 2015
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In this manuscript, we investigate the exchange of air masses across the dynamical tropopause (stratosphere-troposphere exchange, STE) in the vicinity of North Atlantic cyclones. By using two 6-hourly resolved ERA-Interim climatologies of STE and cyclones from 1979 to 2011, we are able to directly compute the amount of STE in the vicinity of every individual cyclone in this time period. This enables us to provide a robust and consistent quantification of STE near North Atlantic cyclones.
M. Sprenger and H. Wernli
Geosci. Model Dev., 8, 2569–2586, https://doi.org/10.5194/gmd-8-2569-2015, https://doi.org/10.5194/gmd-8-2569-2015, 2015
A. Kunz, N. Spelten, P. Konopka, R. Müller, R. M. Forbes, and H. Wernli
Atmos. Chem. Phys., 14, 10803–10822, https://doi.org/10.5194/acp-14-10803-2014, https://doi.org/10.5194/acp-14-10803-2014, 2014
T. Trickl, H. Vogelmann, H. Giehl, H.-E. Scheel, M. Sprenger, and A. Stohl
Atmos. Chem. Phys., 14, 9941–9961, https://doi.org/10.5194/acp-14-9941-2014, https://doi.org/10.5194/acp-14-9941-2014, 2014
E. Flaounas, V. Kotroni, K. Lagouvardos, and I. Flaounas
Geosci. Model Dev., 7, 1841–1853, https://doi.org/10.5194/gmd-7-1841-2014, https://doi.org/10.5194/gmd-7-1841-2014, 2014
P. Reutter, J. Trentmann, A. Seifert, P. Neis, H. Su, D. Chang, M. Herzog, H. Wernli, M. O. Andreae, and U. Pöschl
Atmos. Chem. Phys., 14, 7573–7583, https://doi.org/10.5194/acp-14-7573-2014, https://doi.org/10.5194/acp-14-7573-2014, 2014
C. M. Grams, H. Binder, S. Pfahl, N. Piaget, and H. Wernli
Nat. Hazards Earth Syst. Sci., 14, 1691–1702, https://doi.org/10.5194/nhess-14-1691-2014, https://doi.org/10.5194/nhess-14-1691-2014, 2014
A. Winschall, S. Pfahl, H. Sodemann, and H. Wernli
Atmos. Chem. Phys., 14, 6605–6619, https://doi.org/10.5194/acp-14-6605-2014, https://doi.org/10.5194/acp-14-6605-2014, 2014
F. Aemisegger, S. Pfahl, H. Sodemann, I. Lehner, S. I. Seneviratne, and H. Wernli
Atmos. Chem. Phys., 14, 4029–4054, https://doi.org/10.5194/acp-14-4029-2014, https://doi.org/10.5194/acp-14-4029-2014, 2014
B. Škerlak, M. Sprenger, and H. Wernli
Atmos. Chem. Phys., 14, 913–937, https://doi.org/10.5194/acp-14-913-2014, https://doi.org/10.5194/acp-14-913-2014, 2014
A. K. Miltenberger, S. Pfahl, and H. Wernli
Geosci. Model Dev., 6, 1989–2004, https://doi.org/10.5194/gmd-6-1989-2013, https://doi.org/10.5194/gmd-6-1989-2013, 2013
C. Frick, A. Seifert, and H. Wernli
Geosci. Model Dev., 6, 1925–1939, https://doi.org/10.5194/gmd-6-1925-2013, https://doi.org/10.5194/gmd-6-1925-2013, 2013
Related subject area
Links between the atmospheric water cycle and weather systems
Influence of mid-latitude Sea Surface Temperature Fronts on the Atmospheric Water Cycle and Storm Track Activity
Impact of precipitation mass sinks on midlatitude storms in idealized simulations across a wide range of climates
The monthly evolution of precipitation and warm conveyor belts during the central southwest Asia wet season
Exploring hail and lightning diagnostics over the Alpine-Adriatic region in a km-scale climate model
Model-simulated hydroclimate in the East Asian summer monsoon region during past and future climate: a pilot study with a moisture source perspective
Lagrangian formation pathways of moist anomalies in the trade-wind region during the dry season: two case studies from EUREC4A
A numerical study to investigate the roles of former Hurricane Leslie, orography and evaporative cooling in the 2018 Aude heavy-precipitation event
High-resolution stable isotope signature of a land-falling atmospheric river in southern Norway
Atmospheric convergence zones stemming from large-scale mixing
The role of air–sea fluxes for the water vapour isotope signals in the cold and warm sectors of extratropical cyclones over the Southern Ocean
Attribution of precipitation to cyclones and fronts over Europe in a kilometer-scale regional climate simulation
An attempt to explain recent changes in European snowfall extremes
Fumiaki Ogawa and Thomas Spengler
EGUsphere, https://doi.org/10.5194/egusphere-2024-735, https://doi.org/10.5194/egusphere-2024-735, 2024
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The exchange of energy and moisture between the atmosphere and ocean maximises along strong meridional contrasts in sea surface temperature, such as across the Gulf Stream and Kuroshio. We find that these strong meridional contrasts confine and determine the position of evaporation and precipitation, as well as the storm occurrence and intensity. The general intensity of the water cycle and storm activity, however, are determined by the underlying absolute sea surface temperature.
Tristan H. Abbott and Paul A. O'Gorman
Weather Clim. Dynam., 5, 17–41, https://doi.org/10.5194/wcd-5-17-2024, https://doi.org/10.5194/wcd-5-17-2024, 2024
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Atmospheric models often neglect the mass sink from precipitation fallout, but a small number of modeling studies suggest that this mass sink may intensify storms. We provide evidence, using simulations and theory, that precipitation mass sinks have little systematic effect on storm intensity unless exaggerated by an order of magnitude. This result holds even in very warm climates with very heavy rainfall and helps to justify the neglect of precipitation mass sinks in atmospheric models.
Melissa Leah Breeden, Andrew Hoell, John Robert Albers, and Kimberly Slinski
Weather Clim. Dynam., 4, 963–980, https://doi.org/10.5194/wcd-4-963-2023, https://doi.org/10.5194/wcd-4-963-2023, 2023
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We compare the month-to-month evolution of daily precipitation over central southwest Asia (CSWA), a data-sparse, food-insecure area prone to drought and flooding. The seasonality of CSWA precipitation aligns with the seasonality of warm conveyor belts (WCBs), the warm, rapidly ascending airstreams associated with extratropical storms, most common from February–April. El Niño conditions are related to more WCBs and precipitation and La Niña conditions the opposite, except in January.
Ruoyi Cui, Nikolina Ban, Marie-Estelle Demory, Raffael Aellig, Oliver Fuhrer, Jonas Jucker, Xavier Lapillonne, and Christoph Schär
Weather Clim. Dynam., 4, 905–926, https://doi.org/10.5194/wcd-4-905-2023, https://doi.org/10.5194/wcd-4-905-2023, 2023
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Our study focuses on severe convective storms that occur over the Alpine-Adriatic region. By running simulations for eight real cases and evaluating them against available observations, we found our models did a good job of simulating total precipitation, hail, and lightning. Overall, this research identified important meteorological factors for hail and lightning, and the results indicate that both HAILCAST and LPI diagnostics are promising candidates for future climate research.
Astrid Fremme, Paul J. Hezel, Øyvind Seland, and Harald Sodemann
Weather Clim. Dynam., 4, 449–470, https://doi.org/10.5194/wcd-4-449-2023, https://doi.org/10.5194/wcd-4-449-2023, 2023
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We study the atmospheric moisture transport into eastern China for past, present, and future climate. Hence, we use different climate and weather prediction model data with a moisture source identification method. We find that while the moisture to first order originates mostly from similar regions, smaller changes consistently point to differences in the recycling of precipitation over land between different climates. Some differences are larger between models than between different 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.
Marc Mandement and Olivier Caumont
Weather Clim. Dynam., 2, 795–818, https://doi.org/10.5194/wcd-2-795-2021, https://doi.org/10.5194/wcd-2-795-2021, 2021
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On 14–15 October 2018, in the Aude department (France), a heavy-precipitation event produced up to about 300 mm of rain in 11 h. Simulations carried out show that the former Hurricane Leslie, while involved, was not the first supplier of moisture over the entire event. The location of the highest rainfall was primarily driven by the location of a quasi-stationary front and secondarily by the location of precipitation bands downwind of mountains bordering the Mediterranean Sea.
Yongbiao Weng, Aina Johannessen, and Harald Sodemann
Weather Clim. Dynam., 2, 713–737, https://doi.org/10.5194/wcd-2-713-2021, https://doi.org/10.5194/wcd-2-713-2021, 2021
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High-resolution measurements of stable isotopes in near-surface vapour and precipitation show a
W-shaped evolution during a 24 h land-falling atmospheric river event in southern Norway. We distinguish contributions from below-cloud processes, weather system characteristics, and moisture source conditions during different stages of the event. Rayleigh distillation models need to be expanded by additional processes to accurately predict isotopes in surface precipitation from stratiform clouds.
Gabriel M. P. Perez, Pier Luigi Vidale, Nicholas P. Klingaman, and Thomas C. M. Martin
Weather Clim. Dynam., 2, 475–488, https://doi.org/10.5194/wcd-2-475-2021, https://doi.org/10.5194/wcd-2-475-2021, 2021
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Much of the rainfall in tropical regions comes from organised cloud bands called convergence zones (CZs). These bands have hundreds of kilometers. In South America (SA), they cause intense rain for long periods of time. To study these systems, we need to define and identify them with computer code. We propose a definition of CZs based on the the pathways of air, selecting regions where air masses originated in separated regions meet. This method identifies important mechanisms of rain in SA.
Iris Thurnherr, Katharina Hartmuth, Lukas Jansing, Josué Gehring, Maxi Boettcher, Irina Gorodetskaya, Martin Werner, Heini Wernli, and Franziska Aemisegger
Weather Clim. Dynam., 2, 331–357, https://doi.org/10.5194/wcd-2-331-2021, https://doi.org/10.5194/wcd-2-331-2021, 2021
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Extratropical cyclones are important for the transport of moisture from low to high latitudes. In this study, we investigate how the isotopic composition of water vapour is affected by horizontal temperature advection associated with extratropical cyclones using measurements and modelling. It is shown that air–sea moisture fluxes induced by this horizontal temperature advection lead to the strong variability observed in the isotopic composition of water vapour in the marine boundary layer.
Stefan Rüdisühli, Michael Sprenger, David Leutwyler, Christoph Schär, and Heini Wernli
Weather Clim. Dynam., 1, 675–699, https://doi.org/10.5194/wcd-1-675-2020, https://doi.org/10.5194/wcd-1-675-2020, 2020
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Most precipitation over Europe is linked to low-pressure systems, cold fronts, warm fronts, or high-pressure systems. Based on a massive computer simulation able to resolve thunderstorms, we quantify in detail how much precipitation these weather systems produced during 2000–2008. We find distinct seasonal and regional differences, such as fronts precipitating a lot in fall and winter over the North Atlantic but high-pressure systems mostly in summer over the continent by way of thunderstorms.
Davide Faranda
Weather Clim. Dynam., 1, 445–458, https://doi.org/10.5194/wcd-1-445-2020, https://doi.org/10.5194/wcd-1-445-2020, 2020
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Despite the global temperature rise caused by anthropogenic emissions, we still observe heavy snowfalls that cause casualties, transport disruptions and energy supply problems. The goal of this paper is to investigate recent trends in snowfalls from reanalysis and observational datasets. The analysis shows an evident discrepancy between trends in average and extreme snowfalls. The latter can only be explained by looking at atmospheric circulation.
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Short summary
In this study we identify the wettest seasons globally and address their meteorological characteristics. We show that in different regions the wettest seasons occur in different times of the year and result from either unusually high frequencies of wet days and/or daily extremes. These high frequencies can be largely attributed to four specific weather systems, especially cyclones. Our analysis uses a thoroughly explained, novel methodology that could also be applied to climate models.
In this study we identify the wettest seasons globally and address their meteorological...
