Articles | Volume 5, issue 2
https://doi.org/10.5194/wcd-5-491-2024
© Author(s) 2024. 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-5-491-2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Influence of radiosonde observations on the sharpness and altitude of the midlatitude tropopause in the ECMWF IFS
Konstantin Krüger
CORRESPONDING AUTHOR
Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany
Andreas Schäfler
Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany
Martin Weissmann
Institut für Meteorologie und Geophysik, Universität Wien, Vienna, Austria
George C. Craig
Meteorologisches Institut München, Ludwig-Maximilians-Universität, Munich, Germany
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Konstantin Krüger, Andreas Schäfler, Martin Wirth, Martin Weissmann, and George C. Craig
Atmos. Chem. Phys., 22, 15559–15577, https://doi.org/10.5194/acp-22-15559-2022, https://doi.org/10.5194/acp-22-15559-2022, 2022
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A comprehensive data set of airborne lidar water vapour profiles is compared with ERA5 reanalyses for a robust characterization of the vertical structure of the mid-latitude lower-stratospheric moist bias. We confirm a moist bias of up to 55 % at 1.3 km altitude above the tropopause and uncover a decreasing bias beyond. Collocated O3 and H2O observations reveal a particularly strong bias in the mixing layer, indicating insufficiently modelled transport processes fostering the bias.
Oriol Tintó Prims, Robert Redl, Marc Rautenhaus, Tobias Selz, Takumi Matsunobu, Kameswar Rao Modali, and George Craig
EGUsphere, https://doi.org/10.5194/egusphere-2024-753, https://doi.org/10.5194/egusphere-2024-753, 2024
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Advanced compression techniques can drastically reduce the size of meteorological datasets (by 5x to 150x) without compromising the data's scientific value. We developed a user-friendly tool called 'enstools-compression' that makes this compression simple for Earth scientists. This tool works seamlessly with common weather and climate data formats. Our work shows that lossy compression can significantly improve how researchers store and analyze large meteorological datasets.
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.
Andreas A. Beckert, Lea Eisenstein, Annika Oertel, Tim Hewson, George C. Craig, and Marc Rautenhaus
Geosci. Model Dev., 16, 4427–4450, https://doi.org/10.5194/gmd-16-4427-2023, https://doi.org/10.5194/gmd-16-4427-2023, 2023
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We investigate the benefit of objective 3-D front detection with modern interactive visual analysis techniques for case studies of extra-tropical cyclones and comparisons of frontal structures between different numerical weather prediction models. The 3-D frontal structures show agreement with 2-D fronts from surface analysis charts and augment them in the vertical dimension. We see great potential for more complex studies of atmospheric dynamics and for operational weather forecasting.
Anne Martin, Martin Weissmann, and Alexander Cress
Weather Clim. Dynam., 4, 249–264, https://doi.org/10.5194/wcd-4-249-2023, https://doi.org/10.5194/wcd-4-249-2023, 2023
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Global wind profiles from the Aeolus satellite mission are an important recent substitute for the Global Observing System, showing an overall positive impact on numerical weather prediction forecasts. This study highlights atmospheric dynamic phenomena constituting pathways for significant improvement of Aeolus for future studies, including large-scale tropical circulation systems and the interaction of tropical cyclones undergoing an extratropical transition with the midlatitude waveguide.
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.
Tobias Necker, David Hinger, Philipp Johannes Griewank, Takemasa Miyoshi, and Martin Weissmann
Nonlin. Processes Geophys., 30, 13–29, https://doi.org/10.5194/npg-30-13-2023, https://doi.org/10.5194/npg-30-13-2023, 2023
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This study investigates vertical localization based on a convection-permitting 1000-member ensemble simulation. We derive an empirical optimal localization (EOL) that minimizes sampling error in 40-member sub-sample correlations assuming 1000-member correlations as truth. The results will provide guidance for localization in convective-scale ensemble data assimilation systems.
Konstantin Krüger, Andreas Schäfler, Martin Wirth, Martin Weissmann, and George C. Craig
Atmos. Chem. Phys., 22, 15559–15577, https://doi.org/10.5194/acp-22-15559-2022, https://doi.org/10.5194/acp-22-15559-2022, 2022
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A comprehensive data set of airborne lidar water vapour profiles is compared with ERA5 reanalyses for a robust characterization of the vertical structure of the mid-latitude lower-stratospheric moist bias. We confirm a moist bias of up to 55 % at 1.3 km altitude above the tropopause and uncover a decreasing bias beyond. Collocated O3 and H2O observations reveal a particularly strong bias in the mixing layer, indicating insufficiently modelled transport processes fostering the bias.
Benjamin Witschas, Christian Lemmerz, Alexander Geiß, Oliver Lux, Uwe Marksteiner, Stephan Rahm, Oliver Reitebuch, Andreas Schäfler, and Fabian Weiler
Atmos. Meas. Tech., 15, 7049–7070, https://doi.org/10.5194/amt-15-7049-2022, https://doi.org/10.5194/amt-15-7049-2022, 2022
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In August 2018, the first wind lidar Aeolus was launched into space and has since then been providing data of the global wind field. The primary goal of Aeolus was the improvement of numerical weather prediction. To verify the quality of Aeolus wind data, DLR performed four airborne validation campaigns with two wind lidar systems. In this paper, we report on results from the two later campaigns, performed in Iceland and the tropics.
Oliver Lux, Benjamin Witschas, Alexander Geiß, Christian Lemmerz, Fabian Weiler, Uwe Marksteiner, Stephan Rahm, Andreas Schäfler, and Oliver Reitebuch
Atmos. Meas. Tech., 15, 6467–6488, https://doi.org/10.5194/amt-15-6467-2022, https://doi.org/10.5194/amt-15-6467-2022, 2022
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We discuss the influence of different quality control schemes on the results of Aeolus wind product validation and present statistical tools for ensuring consistency and comparability among diverse validation studies with regard to the specific error characteristics of the Rayleigh-clear and Mie-cloudy winds. The developed methods are applied for the validation of Aeolus winds against an ECMWF model background and airborne wind lidar data from the Joint Aeolus Tropical Atlantic Campaign.
Andreas Alexander Beckert, Lea Eisenstein, Annika Oertel, Timothy Hewson, George C. Craig, and Marc Rautenhaus
Weather Clim. Dynam. Discuss., https://doi.org/10.5194/wcd-2022-36, https://doi.org/10.5194/wcd-2022-36, 2022
Preprint withdrawn
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This study revises and extends a previously presented 3-D objective front detection method and demonstrates its benefits to analyse weather dynamics in numerical simulation data. Based on two case studies of extratropical cyclones, we demonstrate the evaluation of conceptual models from dynamic meteorology, illustrate the benefits of our interactive analysis approach by comparing fronts in data with different model resolutions, and study the impact of convection on fronts.
Raphael Kriegmair, Yvonne Ruckstuhl, Stephan Rasp, and George Craig
Nonlin. Processes Geophys., 29, 171–181, https://doi.org/10.5194/npg-29-171-2022, https://doi.org/10.5194/npg-29-171-2022, 2022
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Our regional numerical weather prediction models run at kilometer-scale resolutions. Processes that occur at smaller scales not yet resolved contribute significantly to the atmospheric flow. We use a neural network (NN) to represent the unresolved part of physical process such as cumulus clouds. We test this approach on a simplified, yet representative, 1D model and find that the NN corrections vastly improve the model forecast up to a couple of days.
Oliver Lux, Christian Lemmerz, Fabian Weiler, Uwe Marksteiner, Benjamin Witschas, Stephan Rahm, Alexander Geiß, Andreas Schäfler, and Oliver Reitebuch
Atmos. Meas. Tech., 15, 1303–1331, https://doi.org/10.5194/amt-15-1303-2022, https://doi.org/10.5194/amt-15-1303-2022, 2022
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The article discusses modifications in the wind retrieval of the ALADIN Airborne Demonstrator (A2D) – one of the key instruments for the validation of Aeolus. Thanks to the retrieval refinements, which are demonstrated in the context of two airborne campaigns in 2019, the systematic and random wind errors of the A2D were significantly reduced, thereby enhancing its validation capabilities. Finally, wind comparisons between A2D and Aeolus for the validation of the satellite data are presented.
Stefan Geiss, Leonhard Scheck, Alberto de Lozar, and Martin Weissmann
Atmos. Chem. Phys., 21, 12273–12290, https://doi.org/10.5194/acp-21-12273-2021, https://doi.org/10.5194/acp-21-12273-2021, 2021
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This study demonstrates the benefits of using both visible and infrared satellite channels to evaluate clouds in numerical weather prediction models. Combining these highly resolved observations provides significantly more and complementary information than using only infrared observations. The visible observations are particularly sensitive to subgrid water clouds, which are not well constrained by other observations.
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.
Andreas Schäfler, Andreas Fix, and Martin Wirth
Atmos. Chem. Phys., 21, 5217–5234, https://doi.org/10.5194/acp-21-5217-2021, https://doi.org/10.5194/acp-21-5217-2021, 2021
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First-ever, collocated ozone and water vapor lidar observations across the tropopause are applied to investigate the extratropical transition layer (ExTL). The combined view of a quasi-instantaneous cross section and its tracer–tracer depiction allows us to analyze the ExTL shape and composition and the formation of mixing lines in relation to the dynamic situation. Such lidar data are relevant for future upper-tropospheric and lower-stratospheric investigations and model validations.
Anne Martin, Martin Weissmann, Oliver Reitebuch, Michael Rennie, Alexander Geiß, and Alexander Cress
Atmos. Meas. Tech., 14, 2167–2183, https://doi.org/10.5194/amt-14-2167-2021, https://doi.org/10.5194/amt-14-2167-2021, 2021
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This study provides an overview of validation activities to determine the Aeolus HLOS wind errors and to understand the biases by investigating possible dependencies and testing bias correction approaches. To ensure meaningful validation statistics, collocated radiosondes and two different global NWP models, the ECMWF IFS and the ICON model (DWD), are used as reference data. To achieve an estimate for the Aeolus instrumental error the representativeness errors for the comparisons are evaluated.
Oliver Lux, Christian Lemmerz, Fabian Weiler, Uwe Marksteiner, Benjamin Witschas, Stephan Rahm, Andreas Schäfler, and Oliver Reitebuch
Atmos. Meas. Tech., 11, 3297–3322, https://doi.org/10.5194/amt-11-3297-2018, https://doi.org/10.5194/amt-11-3297-2018, 2018
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This work reports airborne wind lidar observations performed in a recent field campaign. The deployed lidar system serves as a demonstrator for the satellite instrument ALADIN on board Aeolus, which is scheduled for launch in 2018 and will become the first wind lidar in space. After presenting the measurement principle, operation procedures and wind retrieval algorithm, the obtained wind results are validated and discussed, providing valuable information in preparation for the satellite mission.
Benedikt Urbanek, Silke Groß, Andreas Schäfler, and Martin Wirth
Atmos. Meas. Tech., 10, 1653–1664, https://doi.org/10.5194/amt-10-1653-2017, https://doi.org/10.5194/amt-10-1653-2017, 2017
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Cirrus evolution from nucleation to cloud breakup can be investigated with a novel classification scheme based on airborne lidar data. Applying it to a case study from the ML-CIRRUS campaign, we investigate the impact of large-scale dynamics and small-scale gravity lee waves on the detailed spatial distribution of evolution stages in individual clouds. Our scheme may help to gain more insights in optical and radiative properties of cirrus under various formation and life cycle conditions.
Manuel Gutleben, Silke Gross, Martin Wirth, and Andreas Schäfler
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2016-333, https://doi.org/10.5194/amt-2016-333, 2016
Revised manuscript not accepted
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Shallow marine cumulus convection over the Atlantic ocean is studied with observations by airborne and spaceborne lidar instruments. Cloud top height as well as cloud length and cloud gap length distributions are calculated by use of a newly developed algorithm. The distribution of cloud top heights during wintertime measurements shows a two-layer structure. However, significant differences in cloud top height distributions compared to summertime measurements are found.
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.
S. Groß, V. Freudenthaler, K. Schepanski, C. Toledano, A. Schäfler, A. Ansmann, and B. Weinzierl
Atmos. Chem. Phys., 15, 11067–11080, https://doi.org/10.5194/acp-15-11067-2015, https://doi.org/10.5194/acp-15-11067-2015, 2015
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In June and July 2013 dual-wavelength lidar measurements were performed in Barbados to study long-range transported Saharan dust across the Atlantic Ocean and investigate transport-induced changes. The focus of our measurements is the intensive optical properties, the lidar ratio and the particle linear depolarization ratio. While the lidar ratio shows no differences compared to the values of fresh Saharan dust, the particle linear depolarization ratio shows slight differences.
M. Rautenhaus, M. Kern, A. Schäfler, and R. Westermann
Geosci. Model Dev., 8, 2329–2353, https://doi.org/10.5194/gmd-8-2329-2015, https://doi.org/10.5194/gmd-8-2329-2015, 2015
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This article presents "Met.3D", a new open-source tool for the interactive 3D visualization of numerical ensemble weather predictions. Met.3D builds a bridge from proven 2D visualization methods commonly used in meteorology to 3D visualization and implements approaches to using the ensemble to allow the user to assess forecast uncertainty. The article is the first part of a two-paper study discussing how 3D and ensemble visualization can be used in a meaningful way suited to weather forecasting.
M. Rautenhaus, C. M. Grams, A. Schäfler, and R. Westermann
Geosci. Model Dev., 8, 2355–2377, https://doi.org/10.5194/gmd-8-2355-2015, https://doi.org/10.5194/gmd-8-2355-2015, 2015
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This article presents the application of interactive 3D visualization of ensemble
weather predictions to forecasting warm conveyor belt situations during aircraft-based atmospheric research campaigns. A method to predict 3D probabilities of the spatial occurrence of WCBs is developed and integrated into the 3D visualization tool "Met.3D", introduced in the first part of this two-paper study. A case study demonstrates the use of 3D and uncertainty visualization for weather forecasting.
S. Groß, M. Wirth, A. Schäfler, A. Fix, S. Kaufmann, and C. Voigt
Atmos. Meas. Tech., 7, 2745–2755, https://doi.org/10.5194/amt-7-2745-2014, https://doi.org/10.5194/amt-7-2745-2014, 2014
Related subject area
Dynamical processes in midlatitudes
Life cycle dynamics of Greenland blocking from a potential vorticity perspective
Warm conveyor belt characteristics and impacts along the life cycle of extratropical cyclones: case studies and climatological analysis based on ERA5
Analysing 23 years of warm-season derechos in France: a climatology and investigation of synoptic and environmental changes
A Lagrangian framework for detecting and characterizing the descent of foehn from Alpine to local scales
The upstream–downstream connection of North Atlantic and Mediterranean cyclones in semi-idealized simulations
Understanding the vertical temperature structure of recent record-shattering heatwaves
Persistent warm and cold spells in the Northern Hemisphere extratropics: regionalisation, synoptic-scale dynamics and temperature budget
Linking Gulf Stream air–sea interactions to the exceptional blocking episode in February 2019: a Lagrangian perspective
Process-based classification of Mediterranean cyclones using potential vorticity
The relation between Rossby wave-breaking events and low-level weather systems
Aquaplanet simulations with winter and summer hemispheres: model setup and circulation response to warming
Large-scale perspective on the extreme near-surface winds in the central North Atlantic
Seasonally dependent increases in subweekly temperature variability over Southern Hemisphere landmasses detected in multiple reanalyses
Changes in the North Atlantic Oscillation over the 20th Century
Identification of high-wind features within extratropical cyclones using a probabilistic random forest – Part 2: Climatology over Europe
Cold wintertime air masses over Europe: where do they come from and how do they form?
Diabatic effects on the evolution of storm tracks
Atmospheric response to cold wintertime Tibetan Plateau conditions over eastern Asia in climate models
Transient anticyclonic eddies and their relationship to atmospheric block persistence
A composite approach to produce reference datasets for extratropical cyclone tracks: application to Mediterranean cyclones
Thunderstorm environments in Europe
What distinguishes 100-year precipitation extremes over central European river catchments from more moderate extreme events?
Towards a holistic understanding of blocked regime dynamics through a combination of complementary diagnostic perspectives
Moist available potential energy of the mean state of the atmosphere and the thermodynamic potential for warm conveyor belts and convection
Large spread in the representation of compound long-duration dry and hot spells over Europe in CMIP5
Divergent convective outflow in ICON deep convection-permitting and parameterised deep convection simulations
Similarity and variability of blocked weather-regime dynamics in the Atlantic–European region
Anomalous subtropical zonal winds drive decreases in southern Australian frontal rain
Origin of low-tropospheric potential vorticity in Mediterranean cyclones
Robust poleward jet shifts in idealised baroclinic-wave life-cycle experiments with noisy initial conditions
Revisiting the wintertime emergent constraint of the southern hemispheric midlatitude jet response to global warming
The global atmospheric energy transport analysed by a wavelength-based scale separation
European heatwaves in present and future climate simulations: a Lagrangian analysis
Signatures of Eurasian heat waves in global Rossby wave spectra
Impact of grid spacing, convective parameterization and cloud microphysics in ICON simulations of a warm conveyor belt
Recurrent Rossby waves and south-eastern Australian heatwaves
Identification of high-wind features within extratropical cyclones using a probabilistic random forest – Part 1: Method and case studies
Classification of Alpine south foehn based on 5 years of kilometre-scale analysis data
Meridional-energy-transport extremes and the general circulation of Northern Hemisphere mid-latitudes: dominant weather regimes and preferred zonal wavenumbers
Summertime Rossby waves in climate models: substantial biases in surface imprint associated with small biases in upper-level circulation
Diabatic processes modulating the vertical structure of the jet stream above the cold front of an extratropical cyclone: sensitivity to deep convection schemes
The role of cyclones and potential vorticity cutoffs for the occurrence of unusually long wet spells in Europe
Orographic resolution driving the improvements associated with horizontal resolution increase in the Northern Hemisphere winter mid-latitudes
Quantifying climate model representation of the wintertime Euro-Atlantic circulation using geopotential-jet regimes
Circumglobal Rossby wave patterns during boreal winter highlighted by space–time spectral analysis
How intense daily precipitation depends on temperature and the occurrence of specific weather systems – an investigation with ERA5 reanalyses in the extratropical Northern Hemisphere
Differentiating lightning in winter and summer with characteristics of the wind field and mass field
Future changes in the extratropical storm tracks and cyclone intensity, wind speed, and structure
Atmospheric blocking and weather extremes over the Euro-Atlantic sector – a review
Is it north or west foehn? A Lagrangian analysis of Penetration and Interruption of Alpine Foehn intensive observation period 1 (PIANO IOP 1)
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.
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.
Lucas Fery and Davide Faranda
Weather Clim. Dynam., 5, 439–461, https://doi.org/10.5194/wcd-5-439-2024, https://doi.org/10.5194/wcd-5-439-2024, 2024
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In this study, we analyse warm-season derechos – a type of severe convective windstorm – in France between 2000 and 2022, identifying 38 events. We compare their frequency and features with other countries. We also examine changes in the associated large-scale patterns. We find that convective instability has increased in southern Europe. However, the attribution of these changes to natural climate variability, human-induced climate change or a combination of both remains unclear.
Lukas Jansing, Lukas Papritz, and Michael Sprenger
Weather Clim. Dynam., 5, 463–489, https://doi.org/10.5194/wcd-5-463-2024, https://doi.org/10.5194/wcd-5-463-2024, 2024
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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.
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.
Belinda Hotz, Lukas Papritz, and Matthias Röthlisberger
Weather Clim. Dynam., 5, 323–343, https://doi.org/10.5194/wcd-5-323-2024, https://doi.org/10.5194/wcd-5-323-2024, 2024
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Analysing the vertical structure of temperature anomalies of recent record-breaking heatwaves reveals a complex four-dimensional interplay of anticyclone–heatwave interactions, with vertically strongly varying advective, adiabatic, and diabatic contributions to the respective temperature anomalies. The heatwaves featured bottom-heavy positive temperature anomalies, extending throughout the troposphere.
Alexandre Tuel and Olivia Martius
Weather Clim. Dynam., 5, 263–292, https://doi.org/10.5194/wcd-5-263-2024, https://doi.org/10.5194/wcd-5-263-2024, 2024
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Warm and cold spells often have damaging consequences for agriculture, power demand, human health and infrastructure, especially when they occur over large areas and persist for a week or more. Here, we split the Northern Hemisphere extratropics into coherent regions where 3-week warm and cold spells in winter and summer are associated with the same large-scale circulation patterns. To understand their physical drivers, we analyse the associated circulation and temperature budget anomalies.
Marta Wenta, Christian M. Grams, Lukas Papritz, and Marc Federer
Weather Clim. Dynam., 5, 181–209, https://doi.org/10.5194/wcd-5-181-2024, https://doi.org/10.5194/wcd-5-181-2024, 2024
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Our study links air–sea interactions over the Gulf Stream to an atmospheric block in February 2019. We found that over 23 % of air masses that were lifted into the block by cyclones interacted with the Gulf Stream. As cyclones pass over the Gulf Stream, they cause intense surface evaporation events, preconditioning the environment for the development of cyclones. This implies that air–sea interactions over the Gulf Stream affect the large-scale dynamics in the North Atlantic–European region.
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.
Talia Tamarin-Brodsky and Nili Harnik
Weather Clim. Dynam., 5, 87–108, https://doi.org/10.5194/wcd-5-87-2024, https://doi.org/10.5194/wcd-5-87-2024, 2024
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Synoptic waves in the atmosphere tend to follow a typical Rossby wave lifecycle, involving a linear growth stage followed by nonlinear and irreversible Rossby wave breaking (RWB). Here we take a new approach to study RWB events and their fundamental relation to weather systems by combining a storm-tracking technique and an RWB detection algorithm. The synoptic-scale dynamics leading to RWB is then examined by analyzing time evolution composites of cyclones and anticyclones during RWB events.
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.
Aleksa Stanković, Gabriele Messori, Joaquim G. Pinto, and Rodrigo Caballero
EGUsphere, https://doi.org/10.5194/egusphere-2024-38, https://doi.org/10.5194/egusphere-2024-38, 2024
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The article studies extreme winds near the surface over the North Atlantic ocean. These winds are caused by storms that pass through this region. The strongest storms that have occurred in the winters from 1950–2020 are studied in detail and compared to weaker, but still strong storms. The analysis shows that the storms associated with the strongest winds are preceded by another, older storm that traveled through the same region and made the conditions suitable for development of extreme winds.
Patrick Martineau, Swadhin K. Behera, Masami Nonaka, Hisashi Nakamura, and Yu Kosaka
Weather Clim. Dynam., 5, 1–15, https://doi.org/10.5194/wcd-5-1-2024, https://doi.org/10.5194/wcd-5-1-2024, 2024
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The representation of subweekly near-surface temperature variability trends over the Southern Hemisphere landmasses is compared across multiple atmospheric reanalyses. It is found that there is generally a good agreement concerning the positive trends affecting South Africa and Australia in the spring, and South America in the summer. A more efficient generation of subweekly temperature variance by horizontal temperature fluxes contributes to the observed rise.
Stephen Outten and Richard Davy
EGUsphere, https://doi.org/10.5194/egusphere-2023-2832, https://doi.org/10.5194/egusphere-2023-2832, 2023
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The North Atlantic Oscillation is linked to wintertime weather events over Europe. One feature often overlooked is how much the climate variability explained by the NAO has changed over time. We show that there has been a considerable increase in the percentage variance explained by the NAO over the 20th century, and that this is not reproduced by 50 CMIP6 climate models, which are generally biased too high. This has implications for projections and prediction of weather events in the region.
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.
Tiina Nygård, Lukas Papritz, Tuomas Naakka, and Timo Vihma
Weather Clim. Dynam., 4, 943–961, https://doi.org/10.5194/wcd-4-943-2023, https://doi.org/10.5194/wcd-4-943-2023, 2023
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Despite the general warming trend, wintertime cold-air outbreaks in Europe have remained nearly as extreme and as common as decades ago. In this study, we identify six principal cold anomaly types over Europe in 1979–2020. We show the origins of various physical processes and their contributions to the formation of cold wintertime air masses.
Andrea Marcheggiani and Thomas Spengler
Weather Clim. Dynam., 4, 927–942, https://doi.org/10.5194/wcd-4-927-2023, https://doi.org/10.5194/wcd-4-927-2023, 2023
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There is a gap between the theoretical understanding and model representation of moist diabatic effects on the evolution of storm tracks. We seek to bridge this gap by exploring the relationship between diabatic and adiabatic contributions to changes in baroclinicity. We find reversed behaviours in the lower and upper troposphere in the maintenance of baroclinicity. In particular, our study reveals a link between higher moisture availability and upper-tropospheric restoration of baroclinicity.
Alice Portal, Fabio D'Andrea, Paolo Davini, Mostafa E. Hamouda, and Claudia Pasquero
Weather Clim. Dynam., 4, 809–822, https://doi.org/10.5194/wcd-4-809-2023, https://doi.org/10.5194/wcd-4-809-2023, 2023
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The differences between climate models can be exploited to infer how specific aspects of the climate influence the Earth system. This work analyses the effects of a negative temperature anomaly over the Tibetan Plateau on the winter atmospheric circulation. We show that models with a colder-than-average Tibetan Plateau present a reinforcement of the eastern Asian winter monsoon and discuss the atmospheric response to the enhanced transport of cold air from the continent toward the Pacific Ocean.
Charlie C. Suitters, Oscar Martínez-Alvarado, Kevin I. Hodges, Reinhard K. H. Schiemann, and Duncan Ackerley
Weather Clim. Dynam., 4, 683–700, https://doi.org/10.5194/wcd-4-683-2023, https://doi.org/10.5194/wcd-4-683-2023, 2023
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Atmospheric blocking describes large and persistent high surface pressure. In this study, the relationship between block persistence and smaller-scale systems is examined. Persistent blocks result from more interactions with small systems, but a block's persistence does not depend as strongly on the strength of these smaller features. This work is important because it provides more knowledge as to how blocks can be allowed to persist, which is something we still do not fully understand.
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
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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.
Deborah Morgenstern, Isabell Stucke, Georg J. Mayr, Achim Zeileis, and Thorsten Simon
Weather Clim. Dynam., 4, 489–509, https://doi.org/10.5194/wcd-4-489-2023, https://doi.org/10.5194/wcd-4-489-2023, 2023
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Two thunderstorm environments are described for Europe: mass-field thunderstorms, which occur mostly in summer, over land, and under similar meteorological conditions, and wind-field thunderstorms, which occur mostly in winter, over the sea, and under more diverse meteorological conditions. Our descriptions are independent of static thresholds and help to understand why thunderstorms in unfavorable seasons for lightning pose a particular risk to tall infrastructure such as wind turbines.
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.
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.
Colin Manning, Martin Widmann, Douglas Maraun, Anne F. Van Loon, and Emanuele Bevacqua
Weather Clim. Dynam., 4, 309–329, https://doi.org/10.5194/wcd-4-309-2023, https://doi.org/10.5194/wcd-4-309-2023, 2023
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Climate models differ in their representation of dry spells and high temperatures, linked to errors in the simulation of persistent large-scale anticyclones. Models that simulate more persistent anticyclones simulate longer and hotter dry spells, and vice versa. This information is important to consider when assessing the likelihood of such events in current and future climate simulations so that we can assess the plausibility of their future projections.
Edward Groot, Patrick Kuntze, Annette Katharina Miltenberger, and Holger Tost
EGUsphere, https://doi.org/10.5194/egusphere-2023-664, https://doi.org/10.5194/egusphere-2023-664, 2023
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Deep convective clouds systems are often associated with severe weather conditions. They can organise into coherent convective cloud systems. Accurate representation in numerical weather prediction is challenging due to the dynamics of the systems and its dependency on resolution. Here, the effect of convective organisation and geometry on outflow winds (altitudes of 7–14 km) is investigated. The divergent outflow originating from these systems is represented in more detail at higher resolution.
Franziska Teubler, Michael Riemer, Christopher Polster, Christian M. Grams, Seraphine Hauser, and Volkmar Wirth
Weather Clim. Dynam., 4, 265–285, https://doi.org/10.5194/wcd-4-265-2023, https://doi.org/10.5194/wcd-4-265-2023, 2023
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Weather regimes govern an important part of the sub-seasonal variability of the mid-latitude circulation. The year-round dynamics of blocked regimes in the Atlantic European region are investigated in over 40 years of data. We show that the dynamics between the regimes are on average very similar. Within the regimes, the main variability – starting from the characteristics of dynamical processes alone – dominates and transcends the variability in season and types of transitions.
Acacia S. Pepler and Irina Rudeva
Weather Clim. Dynam., 4, 175–188, https://doi.org/10.5194/wcd-4-175-2023, https://doi.org/10.5194/wcd-4-175-2023, 2023
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In recent decades, cold fronts have rained less often in southeast Australia, which contributes to decreasing cool season rainfall. The largest changes in front dynamics are found to the north of the area where rain changes. Wet fronts have strong westerly winds that reach much further north than dry fronts do, and these fronts are becoming less common, linked to weakening subtropical winds and changes in the Southern Hemisphere circulation.
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.
Felix Jäger, Philip Rupp, and Thomas Birner
Weather Clim. Dynam., 4, 49–60, https://doi.org/10.5194/wcd-4-49-2023, https://doi.org/10.5194/wcd-4-49-2023, 2023
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Mid-latitude weather is dominated by the growth, breaking and decay of baroclinic waves and associated jet shifts. A way to study this process is via idealised life-cycle simulations, which are often classified as LC1 (anticyclonic breaking, poleward shift) or LC2 (cyclonic breaking, equatorward shift), depending on details of the initial state. We show that all systems exhibit predominantly anticyclonic character and poleward net shifts if multiple wave modes are allowed to grow simultaneously.
Philipp Breul, Paulo Ceppi, and Theodore G. Shepherd
Weather Clim. Dynam., 4, 39–47, https://doi.org/10.5194/wcd-4-39-2023, https://doi.org/10.5194/wcd-4-39-2023, 2023
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Accurately predicting the response of the midlatitude jet stream to climate change is very important, but models show a variety of possible scenarios. Previous work identified a relationship between climatological jet latitude and future jet shift in the southern hemispheric winter. We show that the relationship does not hold in separate sectors and propose that zonal asymmetries are the ultimate cause in the zonal mean. This questions the usefulness of the relationship.
Patrick Johannes Stoll, Rune Grand Graversen, and Gabriele Messori
Weather Clim. Dynam., 4, 1–17, https://doi.org/10.5194/wcd-4-1-2023, https://doi.org/10.5194/wcd-4-1-2023, 2023
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The atmosphere is in motion and hereby transporting warm, cold, moist, and dry air to different climate zones. In this study, we investigate how this transport of energy organises in different manners. Outside the tropics, atmospheric waves of sizes between 2000 and 8000 km, which we perceive as cyclones from the surface, transport most of the energy and moisture poleward. In the winter, large-scale weather situations become very important for transporting energy into the polar regions.
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.
Iana Strigunova, Richard Blender, Frank Lunkeit, and Nedjeljka Žagar
Weather Clim. Dynam., 3, 1399–1414, https://doi.org/10.5194/wcd-3-1399-2022, https://doi.org/10.5194/wcd-3-1399-2022, 2022
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We show that the Eurasian heat waves (HWs) have signatures in the global circulation. We present changes in the probability density functions (PDFs) of energy anomalies in the zonal-mean state and in the Rossby waves at different zonal scales in relation to the changes in intramonthly variability. The skewness of the PDF of planetary-scale Rossby waves is shown to increase during HWs, while their intramonthly variability is reduced, a process referred to as blocking.
Anubhav Choudhary and Aiko Voigt
Weather Clim. Dynam., 3, 1199–1214, https://doi.org/10.5194/wcd-3-1199-2022, https://doi.org/10.5194/wcd-3-1199-2022, 2022
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The warm conveyor belt (WCB), which is a stream of coherently rising air parcels, is an important feature of extratropical cyclones. This work presents the impact of model grid spacing on simulation of cloud diabatic processes in the WCB of a North Atlantic cyclone. We find that the refinement of the model grid systematically enhances the dynamical properties and heat releasing processes within the WCB. However, this pattern does not have a strong impact on the strength of associated cyclones.
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.
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.
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.
Valerio Lembo, Federico Fabiano, Vera Melinda Galfi, Rune Grand Graversen, Valerio Lucarini, and Gabriele Messori
Weather Clim. Dynam., 3, 1037–1062, https://doi.org/10.5194/wcd-3-1037-2022, https://doi.org/10.5194/wcd-3-1037-2022, 2022
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Eddies in mid-latitudes characterize the exchange of heat between the tropics and the poles. This exchange is largely uneven, with a few extreme events bearing most of the heat transported across latitudes in a season. It is thus important to understand what the dynamical mechanisms are behind these events. Here, we identify recurrent weather regime patterns associated with extreme transports, and we identify scales of mid-latitudinal eddies that are mostly responsible for the transport.
Fei Luo, Frank Selten, Kathrin Wehrli, Kai Kornhuber, Philippe Le Sager, Wilhelm May, Thomas Reerink, Sonia I. Seneviratne, Hideo Shiogama, Daisuke Tokuda, Hyungjun Kim, and Dim Coumou
Weather Clim. Dynam., 3, 905–935, https://doi.org/10.5194/wcd-3-905-2022, https://doi.org/10.5194/wcd-3-905-2022, 2022
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Recent studies have identified the weather systems in observational data, where wave patterns with high-magnitude values that circle around the whole globe in either wavenumber 5 or wavenumber 7 are responsible for the extreme events. In conclusion, we find that the climate models are able to reproduce the large-scale atmospheric circulation patterns as well as their associated surface variables such as temperature, precipitation, and sea level pressure.
Meryl Wimmer, Gwendal Rivière, Philippe Arbogast, Jean-Marcel Piriou, Julien Delanoë, Carole Labadie, Quitterie Cazenave, and Jacques Pelon
Weather Clim. Dynam., 3, 863–882, https://doi.org/10.5194/wcd-3-863-2022, https://doi.org/10.5194/wcd-3-863-2022, 2022
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The effect of deep convection representation on the jet stream above the cold front of an extratropical cyclone is investigated in the global numerical weather prediction model ARPEGE. Two simulations using different deep convection schemes are compared with (re)analysis datasets and NAWDEX airborne observations. A deeper jet stream is observed with the less active scheme. The diabatic origin of this difference is interpreted by backward Lagrangian trajectories and potential vorticity budgets.
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.
Paolo Davini, Federico Fabiano, and Irina Sandu
Weather Clim. Dynam., 3, 535–553, https://doi.org/10.5194/wcd-3-535-2022, https://doi.org/10.5194/wcd-3-535-2022, 2022
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In climate models, improvements obtained in the winter mid-latitude circulation following horizontal resolution increase are mainly caused by the more detailed representation of the mean orography. A high-resolution climate model with low-resolution orography might underperform compared to a low-resolution model with low-resolution orography. The absence of proper model tuning at high resolution is considered the potential reason behind such lack of improvements.
Joshua Dorrington, Kristian Strommen, and Federico Fabiano
Weather Clim. Dynam., 3, 505–533, https://doi.org/10.5194/wcd-3-505-2022, https://doi.org/10.5194/wcd-3-505-2022, 2022
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We investigate how well current state-of-the-art climate models reproduce the wintertime weather of the North Atlantic and western Europe by studying how well different "regimes" of weather are captured. Historically, models have struggled to capture these regimes, making it hard to predict future changes in wintertime extreme weather. We show models can capture regimes if the right method is used, but they show biases, partially as a result of biases in jet speed and eddy strength.
Jacopo Riboldi, Efi Rousi, Fabio D'Andrea, Gwendal Rivière, and François Lott
Weather Clim. Dynam., 3, 449–469, https://doi.org/10.5194/wcd-3-449-2022, https://doi.org/10.5194/wcd-3-449-2022, 2022
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A revisited space and time spectral decomposition allows us to determine which harmonics dominate the upper-tropospheric flow evolution over a given time period as well as their propagation. This approach is used to identify Rossby wave patterns with a circumglobal extent, affecting weather evolution over different Northern Hemisphere regions. The results cast light on the processes originating and supporting these wave patterns, advocating at the same time for the usefulness of the technique.
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.
Deborah Morgenstern, Isabell Stucke, Thorsten Simon, Georg J. Mayr, and Achim Zeileis
Weather Clim. Dynam., 3, 361–375, https://doi.org/10.5194/wcd-3-361-2022, https://doi.org/10.5194/wcd-3-361-2022, 2022
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Wintertime lightning in central Europe is rare but has a large damage potential for tall structures such as wind turbines. We use a data-driven approach to explain why it even occurs when the meteorological processes causing thunderstorms in summer are absent. In summer, with strong solar input, thunderclouds have a large vertical extent, whereas in winter, thunderclouds are shallower in the vertical but tilted and elongated in the horizontal by strong winds that increase with altitude.
Matthew D. K. Priestley and Jennifer L. Catto
Weather Clim. Dynam., 3, 337–360, https://doi.org/10.5194/wcd-3-337-2022, https://doi.org/10.5194/wcd-3-337-2022, 2022
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We use the newest set of climate model experiments from CMIP6 to investigate changes to mid-latitude storm tracks and cyclones from global warming. The overall number of cyclones will decrease. However in winter there will be more of the most intense cyclones, and these intense cyclones are likely to be stronger. Cyclone wind speeds will increase in winter, and as a result the area of strongest wind speeds will increase. By 2100 the area of strong wind speeds may increase by over 30 %.
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.
Manuel Saigger and Alexander Gohm
Weather Clim. Dynam., 3, 279–303, https://doi.org/10.5194/wcd-3-279-2022, https://doi.org/10.5194/wcd-3-279-2022, 2022
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In this work a special form of a foehn wind in an Alpine valley with a large-scale northwesterly flow is investigated. The study clarifies the origin of the air mass and the mechanisms by which this air enters the valley. A trajectory analysis shows that the location where the main airstream passes the crest line is more suitable for a foehn classification than the local or large-scale wind direction. Mountain waves and a lee rotor were crucial for importing air into the valley.
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Short summary
Initial conditions of current numerical weather prediction models insufficiently represent the sharp vertical gradients across the midlatitude tropopause. Observation-space data assimilation output is used to study the influence of assimilated radiosondes on the tropopause. The radiosondes reduce systematic biases of the model background and sharpen temperature and wind gradients in the analysis. Tropopause sharpness is still underestimated in the analysis, which may impact weather forecasts.
Initial conditions of current numerical weather prediction models insufficiently represent the...