Articles | Volume 1, issue 2
https://doi.org/10.5194/wcd-1-405-2020
© Author(s) 2020. 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-1-405-2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
24 Aug 2020
Research article |
| 24 Aug 2020
| 24 Aug 2020
The sensitivity of atmospheric blocking to upstream latent heating – numerical experiments
Daniel Steinfeld
CORRESPONDING AUTHOR
Institute for Atmospheric and Climate Science, ETH Zürich, Zurich, Switzerland
Maxi Boettcher
Institute for Atmospheric and Climate Science, ETH Zürich, Zurich, Switzerland
Richard Forbes
European Centre for Medium-Range Weather Forecasts, Reading, United Kingdom
Stephan Pfahl
Institute of Meteorology, Freie Universität Berlin, Berlin, Germany
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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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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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Ian Boutle, Wayne Angevine, Jian-Wen Bao, Thierry Bergot, Ritthik Bhattacharya, Andreas Bott, Leo Ducongé, Richard Forbes, Tobias Goecke, Evelyn Grell, Adrian Hill, Adele L. Igel, Innocent Kudzotsa, Christine Lac, Bjorn Maronga, Sami Romakkaniemi, Juerg Schmidli, Johannes Schwenkel, Gert-Jan Steeneveld, and Benoît Vié
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Fog forecasting is one of the biggest problems for numerical weather prediction. By comparing many models used for fog forecasting with others used for fog research, we hoped to help guide forecast improvements. We show some key processes that, if improved, will help improve fog forecasting, such as how water is deposited on the ground. We also showed that research models were not themselves a suitable baseline for comparison, and we discuss what future observations are required to improve them.
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.
Zhihong Zhuo, Ingo Kirchner, Stephan Pfahl, and Ulrich Cubasch
Atmos. Chem. Phys., 21, 13425–13442, https://doi.org/10.5194/acp-21-13425-2021, https://doi.org/10.5194/acp-21-13425-2021, 2021
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The impact of volcanic eruptions varies with eruption season and latitude. This study simulated eruptions at different latitudes and in different seasons with a fully coupled climate model. The climate impacts of northern and southern hemispheric eruptions are reversed but are insensitive to eruption season. Results suggest that the regional climate impacts are due to the dynamical response of the climate system to radiative effects of volcanic aerosols and the subsequent regional feedbacks.
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.
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.
Emmanouil Flaounas, Matthias Röthlisberger, Maxi Boettcher, Michael Sprenger, and Heini Wernli
Weather Clim. Dynam., 2, 71–88, https://doi.org/10.5194/wcd-2-71-2021, https://doi.org/10.5194/wcd-2-71-2021, 2021
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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.
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.
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.
Mareike Schuster, Jens Grieger, Andy Richling, Thomas Schartner, Sebastian Illing, Christopher Kadow, Wolfgang A. Müller, Holger Pohlmann, Stephan Pfahl, and Uwe Ulbrich
Earth Syst. Dynam., 10, 901–917, https://doi.org/10.5194/esd-10-901-2019, https://doi.org/10.5194/esd-10-901-2019, 2019
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Decadal climate predictions are valuable to society as they allow us to estimate climate conditions several years in advance. We analyze the latest version of the German MiKlip prediction system (https://www.fona-miklip.de) and assess the effect of the model resolution on the skill of the system. The increase in the resolution of the system reduces the bias and significantly improves the forecast skill for North Atlantic extratropical winter dynamics for lead times of two to five winters.
Emmanuele Russo, Ingo Kirchner, Stephan Pfahl, Martijn Schaap, and Ulrich Cubasch
Geosci. Model Dev., 12, 5229–5249, https://doi.org/10.5194/gmd-12-5229-2019, https://doi.org/10.5194/gmd-12-5229-2019, 2019
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This is an investigation of COSMO-CLM 5.0 sensitivity for the CORDEX Central Asia domain, with the main goal of evaluating general model performances for the area, proposing a model optimal configuration to be used in projection studies.
Results show that the model seems to be particularly sensitive to those parameterizations that deal with soil and surface features and that could positively affect the repartition of incoming radiation.
Keun-Ok Lee, Franziska Aemisegger, Stephan Pfahl, Cyrille Flamant, Jean-Lionel Lacour, and Jean-Pierre Chaboureau
Atmos. Chem. Phys., 19, 7487–7506, https://doi.org/10.5194/acp-19-7487-2019, https://doi.org/10.5194/acp-19-7487-2019, 2019
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Our study is the first study to investigate the potential benefit of stable water isotopes (SWIs) in the context of a heavy precipitation event in the Mediterranean. As such, our study provides a proof of concept of the usefulness of SWI data to understand the variety of origins and moisture processes associated with air masses feeding the convection over southern Italy.
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.
Johannes Eckstein, Roland Ruhnke, Stephan Pfahl, Emanuel Christner, Christopher Diekmann, Christoph Dyroff, Daniel Reinert, Daniel Rieger, Matthias Schneider, Jennifer Schröter, Andreas Zahn, and Peter Braesicke
Geosci. Model Dev., 11, 5113–5133, https://doi.org/10.5194/gmd-11-5113-2018, https://doi.org/10.5194/gmd-11-5113-2018, 2018
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We present ICON-ART-Iso, an extension to the global circulation model ICON, which allows for the simulation of the stable isotopologues of water. The main advantage over other isotope-enabled models is its flexible design with respect to the number of tracers simulated. We compare the results of several simulations to measurements of different scale. ICON-ART-Iso is able to reasonably reproduce the measurements. It is a promising tool to aid in the investigation of the atmospheric water cycle.
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.
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.
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.
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
M. S. Johnston, S. Eliasson, P. Eriksson, R. M. Forbes, A. Gettelman, P. Räisänen, and M. D. Zelinka
Atmos. Chem. Phys., 14, 8701–8721, https://doi.org/10.5194/acp-14-8701-2014, https://doi.org/10.5194/acp-14-8701-2014, 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
S. Pfahl
Nat. Hazards Earth Syst. Sci., 14, 1461–1475, https://doi.org/10.5194/nhess-14-1461-2014, https://doi.org/10.5194/nhess-14-1461-2014, 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
S. Pfahl and H. Sodemann
Clim. Past, 10, 771–781, https://doi.org/10.5194/cp-10-771-2014, https://doi.org/10.5194/cp-10-771-2014, 2014
M. S. Johnston, S. Eliasson, P. Eriksson, R. M. Forbes, K. Wyser, and M. D. Zelinka
Atmos. Chem. Phys., 13, 12043–12058, https://doi.org/10.5194/acp-13-12043-2013, https://doi.org/10.5194/acp-13-12043-2013, 2013
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
Related subject area
Dynamical processes in midlatitudes
Influence of radiosonde observations on the sharpness and altitude of the midlatitude tropopause in the ECMWF IFS
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
Seasonally dependent increases in subweekly temperature variability over Southern Hemisphere landmasses detected in multiple reanalyses
Life cycle dynamics of Greenland blocking from a potential vorticity perspective
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
Warm conveyor belt characteristics and impacts along the life cycle of extratropical cyclones: Case studies and climatological analysis based on ERA5
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)
Konstantin Krüger, Andreas Schäfler, Martin Weissmann, and George C. Craig
Weather Clim. Dynam., 5, 491–509, https://doi.org/10.5194/wcd-5-491-2024, https://doi.org/10.5194/wcd-5-491-2024, 2024
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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.
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.
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.
Seraphine Hauser, Franziska Teubler, Michael Riemer, Peter Knippertz, and Christian M. Grams
EGUsphere, https://doi.org/10.5194/egusphere-2023-2945, https://doi.org/10.5194/egusphere-2023-2945, 2023
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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.
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.
Katharina Heitmann, Michael Sprenger, Hanin Binder, Heini Wernli, and Hanna Joos
EGUsphere, https://doi.org/10.5194/egusphere-2023-1092, https://doi.org/10.5194/egusphere-2023-1092, 2023
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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.
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.
Cited articles
Ahlgrimm, M. and Forbes, R.: Improving the Representation of Low Clouds and
Drizzle in the ECMWF Model Based on ARM Observations from the Azores, Mon.
Weather Rev., 142, 668–685, https://doi.org/10.1175/MWR-D-13-00153.1, 2013. a
Ahmadi-Givi, F., Graig, G. C., and Plant, R. S.: The dynamics of a midlatitude cyclone with very strong latent-heat release, Q. J. Roy. Meteorol. Soc., 130, 295–323, https://doi.org/10.1256/qj.02.226, 2004. a, b, c
Altenhoff, A. M., Martius, O., Croci-Maspoli, M., Schwierz, C., and Davies,
H. C.: Linkage of atmospheric blocks and synoptic-scale Rossby waves: a
climatological analysis, Tellus A, 60, 1053–1063,
https://doi.org/10.1111/j.1600-0870.2008.00354.x, 2008. a, b
Archambault, H. M., Bosart, L. F., Keyser, D., and Cordeira, J. M.: A
climatological analysis of the extratropical flow response to recurving
western north pacific tropical cyclones, Mon. Weather Rev., 141, 2325–2346,
https://doi.org/10.1175/MWR-D-12-00257.1, 2013. a
Attinger, R., Spreitzer, E., Boettcher, M., Forbes, R., Wernli, H., and Joos,
H.: Quantifying the role of individual diabatic processes for the formation
of PV anomalies in a North Pacific cyclone, Q. J. Roy. Meteorol. Soc., 145,
2454–2476, https://doi.org/10.1002/qj.3573, 2019. a, b
Bechtold, P., Köhler, M., Jung, T., Doblas-Reyes, F., Leutbecher, M.,
Rodwell, M. J., Vitart, F., and Balsamo, G.: Advances in simulating
atmospheric variability with the ECMWF model: From synoptic to decadal
time-scales, Q. J. Roy. Meteorol. Soc., 134, 1337–1351, https://doi.org/10.1002/qj.289, 2008. a
Bechtold, P., Semane, N., Lopez, P., Chaboureau, J.-P., Beljaars, A., and
Bormann, N.: Representing equilibrium and nonequilibrium convection in
large-scale Models, J. Atmos. Sci., 71, 734–753, https://doi.org/10.1175/JAS-D-13-0163.1, 2013. a
Berggren, R., Bolin, B., and Rossby, C.-G.: An aerological study of zonal
motion, its perturbations and break-down, Tellus, 1, 14–37,
https://doi.org/10.1111/j.2153-3490.1949.tb01257.x, 1949. a, b
Binder, H., Boettcher, M., Joos, H., and Wernli, H.: The role of warm conveyor belts for the intensification of extratropical cyclones in Northern
Hemisphere winter, J. Atmos. Sci., 73, 3997–4020,
https://doi.org/10.1175/JAS-D-15-0302.1, 2016. a
Büeler, D. and Pfahl, S.: Potential vorticity diagnostics to quantify
effects of latent heating in extratropical cyclones. Part I: methodology, J.
Atmos. Sci., 74, 3567–3590, https://doi.org/10.1175/JAS-D-17-0041.1, 2017. a
Chagnon, J. M. and Gray, S. L.: A diabatically generated potential vorticity
structure near the extratropical tropopause in three simulated extratropical
cyclones, Mon. Weather Rev., 143, 2337–2347, https://doi.org/10.1175/MWR-D-14-00092.1, 2015. a
Charney, J. G. and DeVore, J. G.: Multiple flow equilibria in the atmosphere
and blocking, J. Atmos. Sci., 36, 1205–1216,
https://doi.org/10.1175/1520-0469(1979)036<1205:MFEITA>2.0.CO;2, 1979. a, b
Colucci, S. J.: Explosive cyclogenesis and large-scale circulation changes:
implications for atmospheric blocking, J. Atmos. Sci., 42, 2701–2717,
https://doi.org/10.1175/1520-0469(1985)042<2701:ECALSC>2.0.CO;2, 1985. a, b, c, d
Colucci, S. J.: Planetary-scale preconditioning for the onset of blocking, J. Atmos. Sci., 58, 933–942,
https://doi.org/10.1175/1520-0469(2001)058<0933:PSPFTO>2.0.CO;2, 2001. a
Croci-Maspoli, M. and Davies, H. C.: Key dynamical features of the 2005/06 European winter, Mon. Weather Rev., 137, 664–678,
https://doi.org/10.1175/2008MWR2533.1, 2009. a, b
Croci-Maspoli, M., Schwierz, C., and Davies, H. C.: A multifaceted climatology of atmospheric blocking and its recent linear trend, J. Climate, 20, 633–649, https://doi.org/10.1175/JCLI4029.1, 2007. a
Davis, C. A., Stoelinga, M. T., and Kuo, Y.-H.: The integrated effect of
condensation in numerical simulations of extratropical cyclogenesis, Mon.
Weather Rev., 121, 2309–2330,
https://doi.org/10.1175/1520-0493(1993)121<2309:TIEOCI>2.0.CO;2, 1993. a, b, c, d
Dearden, C., Vaughan, G., Tsai, T., and Chen, J.-P.: Exploring the diabatic
role of ice microphysical processes in two North Atlantic summer cyclones,
Mon. Weather Rev., 144, 1249–1272, https://doi.org/10.1175/MWR-D-15-0253.1, 2016. a
Dee, D. P., Uppala, S. M., Simmons, A. J., Berrisford, P., Poli, P., Kobayashi, S., Andrae, U., Balmaseda, M. A., Balsamo, G., Bauer, P., Bechtold, P., Beljaars, A. C. M., van de Berg, L., Bidlot, J., Bormann, N., Delsol, C., Dragani, R., Fuentes, M., Geer, A. J., Haimberger, L., Healy, S. B., Hersbach, H., Hólm, E. V., Isaksen, L., Kållberg, P., Köhler,
M., Matricardi, M., Mcnally, A. P., Monge-Sanz, B. M., Morcrette, J. J., Park, B. K., Peubey, C., de Rosnay, P., Tavolato, C., Thépaut, J. N., and Vitart, F.: The ERA-Interim reanalysis: configuration and performance of the data assimilation system, Q. J. Roy. Meteorol. Soc., 137, 553–597,
https://doi.org/10.1002/qj.828, 2011. a
Dole, R. M.: The life cycles of persistent anomalies and blocking over the
North Pacific, Adv. Geophys., 29, 31–69, https://doi.org/10.1016/S0065-2687(08)60034-5, 1986. a
Drouard, M. and Woollings, T.: Contrasting mechanisms of summer blocking over
western Eurasia, Geophys. Res. Lett., 45, 12040–12048, https://doi.org/10.1029/2018GL079894, 2018. a
ECMWF: IFS documentation CY43r1, available at:
https://www.ecmwf.int/en/elibrary/17116-part-iii-dynamics-and-numerical-procedures
(last access: 17 April 2019), 2016a. a
ECMWF: IFS documentation CY43r1, available at:
https://www.ecmwf.int/en/elibrary/17117-part-iv-physical-processes
(last access: 17 April 2019), 2016b. a
EUMETSAT: Cloud top height product: Product guide, available at:
https://www.eumetsat.int/website/home/Data/Products/Atmosphere/index.html
(last access: 17 April 2019), 2017. a
Forbes, R. M. and Ahlgrimm, M.: On the representation of high-latitude
boundary layer mixed-phase cloud in the ECMWF global model, Mon. Weather Rev., 142, 3425–3445, https://doi.org/10.1175/MWR-D-13-00325.1, 2014. a
Forbes, R. M., Tompkins, A. M., and Untch, A.: A new prognostic bulk
microphysics scheme for the IFS, Tech. rep., ECMWF, available at:
http://old.ecmwf.int/publications/library/ecpublications/_pdf/tm/601-700/tm649.pdf
(last access: 17 April 2019), 2011. a
Grams, C. M., Wernli, H., Böttcher, M., Čampa, J., Corsmeier, U.,
Jones, S. C., Keller, J. H., Lenz, C.-J., and Wiegand, L.: The key role of
diabatic processes in modifying the upper-tropospheric wave guide: a North
Atlantic case-study, Q. J. Roy. Meteorol. Soc., 137, 2174–2193,
https://doi.org/10.1002/qj.891, 2011. a, b, c
Grams, C. M., Magnusson, L., and Madonna, E.: An atmospheric dynamics'
perspective on the amplification and propagation of forecast error in numerical weather prediction models: a case study, Q. J. Roy. Meteorol. Soc.,
144, 2577–2591, https://doi.org/10.1002/qj.3353, 2018. a
Green, J. S. A.: The weather during July 1976: Some dynamical consideration of the drought, Weather, 32, 120–126, https://doi.org/10.1002/j.1477-8696.1977.tb04532.x, 1977. a, b
Hoskins, B. J. and Valdes, P. J.: On the existence of storm-tracks, J. Atmos.
Sci., 47, 1854–1864, https://doi.org/10.1175/1520-0469(1990)047<1854:OTEOST>2.0.CO;2, 1989. a
Hoskins, B. J., James, I. N., and White, G. H.: The shape, propagation and
mean-flow interaction of large-scale weather systems, J. Atmos. Sci., 40,
1595–1612, https://doi.org/10.1175/1520-0469(1983)040<1595:TSPAMF>2.0.CO;2, 1983. a
Hoskins, B. J., McIntyre, M. E., and Robertson, A. W.: On the use and
significance of isentropic potential vorticity maps, Q. J. Roy. Meteorol. Soc., 111, 877–946, https://doi.org/10.1002/qj.49711147002, 1985. a, b
Joos, H. and Forbes, R. M.: Impact of different IFS microphysics on a warm
conveyor belt and the downstream flow evolution, Q. J. Roy. Meteorol. Soc.,
142, 2727–2739, https://doi.org/10.1002/qj.2863, 2016. a
Joos, H. and Wernli, H.: Influence of microphysical processes on the potential vorticity development in a warm conveyor belt: A case-study with the limited-area model COSMO, Q. J. Roy. Meteorol. Soc., 138, 407–418,
https://doi.org/10.1002/qj.934, 2012. a, b, c, d
Knippertz, P. and Martin, J. E.: The role of dynamic and diabatic processes in the generation of cut-off lows over Northwest Africa, Meteorol. Atmos.
Phys., 96, 3–19, https://doi.org/10.1007/s00703-006-0217-4, 2007. a
Kuo, Y.-H., Shapiro, M. A., and Donall, E. G.: The interaction between
baroclinic and diabatic processes in a numerical simulation of a rapidly
intensifying extratropical marine cyclone, Mon. Weather Rev., 119, 368–384,
https://doi.org/10.1175/1520-0493(1991)119<0368:TIBBAD>2.0.CO;2, 1990. a, b, c
Lenggenhager, S., Croci-Maspoli, M., Brönnimann, S., and Martius, O.: On
the dynamical coupling between atmospheric blocks and heavy precipitation
events: A discussion of the southern Alpine flood in October 2000, Q. J. Roy.
Meteorol. Soc., 145, 530–545, https://doi.org/10.1002/qj.3449, 2019. a
Luo, D., Cha, J., Zhong, L., and Dai, A.: A nonlinear multiscale interaction
model for atmospheric blocking: The eddy-blocking matching mechanism, Q. J.
Roy. Meteorol. Soc., 140, 1785–1808, https://doi.org/10.1002/qj.2337, 2014. a, b, c
Luo, D., Xiao, Y., Diao, Y., Dai, A., Franzke, C. L. E., and Simmonds, I.:
Impact of Ural blocking on winter warm Arctic – cold Eurasian anomalies.
Part II: the link to the North Atlantic oscillation, J. Climate, 29,
3949–3971, https://doi.org/10.1175/JCLI-D-15-0612.1, 2016. a
Lupo, A. R. and Smith, P. J.: Climatological features of blocking anticyclones in the Northern Hemisphere, Tellus A, 47, 439–456,
https://doi.org/10.1034/j.1600-0870.1995.t01-3-00004.x, 1995. a
Maddison, J. W., Gray, S. L., Martínez-Alvarado, O., and Williams, K. D.:
Impact of model upgrades on diabatic processes in extratropical cyclones and
downstream forecast evolution, Q. J. Roy. Meteorol. Soc., 146, 1322–1350,
https://doi.org/10.1002/qj.3739, 2020. a, b
Madonna, E., Limbach, S., Aebi, C., Joos, H., Wernli, H., and Martius, O.: On
the co-occurrence of warm conveyor belt outflows and PV streamers, J. Atmos.
Sci., 71, 3668–3673, https://doi.org/10.1175/JAS-D-14-0119.1, 2014a. a
Madonna, E., Wernli, H., Joos, H., and Martius, O.: Warm conveyor belts in the ERA-Interim Dataset (1979–2010). Part I: Climatology and potential vorticity evolution, J. Climate, 27, 3–26, https://doi.org/10.1175/JCLI-D-12-00720.1,
2014b. a
Martius, O., Schwierz, C., and Davies, H. C.: Tropopause-level waveguides, J. Atmos. Sci., 67, 866–879, https://doi.org/10.1175/2009JAS2995.1, 2010. a
Matsueda, M.: Blocking predictability in operational medium-range ensemble
forecasts, Scient. Online Lett. Atmos., 5, 113–116, https://doi.org/10.2151/sola.2009-029, 2009. a
Matsueda, M.: Predictability of Euro-Russian blocking in summer of 2010,
Geophys. Res. Lett., 38, L06801, https://doi.org/10.1029/2010GL046557, 2011. a
Methven, J.: Potential vorticity in warm conveyor belt outflow, Q. J. Roy.
Meteorol. Soc., 141, 1065–1071, https://doi.org/10.1002/qj.2393, 2015. a
Mullen, S.: Transient eddy forcing of blocking flows, J. Atmos. Sci., 44,
3–22, https://doi.org/10.1175/1520-0469(1987)044<0003:TEFOBF>2.0.CO;2, 1987. a, b, c
Müller, A. and Névir, P.: Using the concept of the Dynamic State Index for a scale-dependent analysis of atmospheric blocking, Meteorol. Z., 28, 487–498, https://doi.org/10.1127/metz/2019/0963, 2019. a
Nakamura, H. and Wallace, J. M.: Synoptic behavior of baroclinic eddies during the blocking onset, Mon. Weather Rev., 121, 1892–1903,
https://doi.org/10.1175/1520-0493(1993)121<1892:SBOBED>2.0.CO;2, 1993. a
Nakamura, H., Nakamura, M., and Anderson, J. L.: The role of high- and
low-frequency dynamics in blocking formation, Mon. Weather Rev., 125,
2074–2093, https://doi.org/10.1175/1520-0493(1997)125<2074:TROHAL>2.0.CO;2, 1997. a, b, c
Nakamura, N. and Huang, C. S.: Atmospheric blocking as a traffic jam in the
jet stream, Science, 361, 42–47, https://doi.org/10.1126/science.aat0721, 2018. a, b
Oertel, A., Boettcher, M., Joos, H., Sprenger, M., Konow, H., Hagen, M., and
Wernli, H.: Convective activity in an extratropical cyclone and its warm
conveyor belt – a case-study combining observations and a
convection-permitting model simulation, Q. J. Roy. Meteorol. Soc., 145,
1406–1426, https://doi.org/10.1002/qj.3500, 2019. a
Oertel, A., Boettcher, M., Joos, H., Sprenger, M., and Wernli, H.: Potential
vorticity structure of embedded convection in a warm conveyor belt and its
relevance for large-scale dynamics, Weather Clim. Dynam., 1, 127–153,
https://doi.org/10.5194/wcd-1-127-2020, 2020. a, b
Pauley, P. M. and Smith, P. J.: Direct and indirect effects of latent heat
release on a synoptic-Scale wave system, Mon. Weather Rev., 116, 1209–1236,
https://doi.org/10.1175/1520-0493(1988)116<1209:DAIEOL>2.0.CO;2, 1988. a
Petoukhov, V., Rahmstorf, S., Petri, S., and Schellnhuber, H. J.:
Quasiresonant amplification of planetary waves and recent Northern
Hemisphere weather extremes, P. Natl. Acad. Sci. USA, 110, 5336–5341,
https://doi.org/10.1073/pnas.1222000110, 2013. a
Pfahl, S., Schwierz, C., Croci-Maspoli, M., Grams, C. M., and Wernli, H.:
Importance of latent heat release in ascending air streams for atmospheric
blocking, Nat. Geosci., 8, 610–614, https://doi.org/10.1038/ngeo2487, 2015. a, b, c, d
Pomroy, H. R. and Thorpe, A. J.: The evolution and dynamical role of reduced
upper-tropospheric potential vorticity in intensive observing period one of
FASTEX, Mon. Weather Rev., 128, 1817–1834,
https://doi.org/10.1175/1520-0493(2000)128<1817:TEADRO>2.0.CO;2, 2000. a, b
Quandt, L.-A., Keller, J. H., Martius, O., Pinto, J. G., and Jones, S. C.:
Ensemble sensitivity analysis of the blocking system over Russia in summer 2010, Mon. Weather Rev., 147, 657–675, https://doi.org/10.1175/MWR-D-18-0252.1,
2018. a
Quinting, J. F. and Reeder, M. J.: Southeastern Australian heat waves from a
trajectory viewpoint, Mon. Weather Rev., 145, 4109–4125,
https://doi.org/10.1175/MWR-D-17-0165.1, 2017. a
Rex, D. F.: Blocking action in the middle troposphere and its effect upon
regional climate, Tellus, 2, 196–211, https://doi.org/10.1111/j.2153-3490.1950.tb00331.x, 1950. a, b
Riemer, M., Jones, S. C., and Davis, C. A.: The impact of extratropical
transition on the downstream flow: An idealized modelling study with a
straight jet, Q. J. Roy. Meteorol. Soc., 134, 69–91, https://doi.org/10.1002/qj.189,
2008. a
Rodwell, M. J., Magnusson, L., Bauer, P., Bechtold, P., Bonavita, M.,
Cardinali, C., Diamantakis, M., Earnshaw, P., Garcia-Mendez, A., Isaksen, L.,
Källén, E., Klocke, D., Lopez, P., McNally, T., Persson, A., Prates, F., and Wedi, N.: Characteristics of occasional poor medium-range weather forecasts for Europe, B. Am. Meteorol. Soc., 94, 1393–1405,
https://doi.org/10.1175/BAMS-D-12-00099.1, 2013. a, b
Röthlisberger, M., Martius, O., and Wernli, H.: Northern Hemisphere
Rossby wave initiation events on the extratropical jet – a climatological
analysis, J. Climate, 31, 743–760, https://doi.org/10.1175/JCLI-D-17-0346.1, 2018. a, b
Schäfler, A., Craig, G., Wernli, H., Arbogast, P., Doyle, J. D.,
McTaggart-Cowan, R., Methven, J., Rivière, G., Ament, F., Boettcher, M., Bramberger, M., Cazenave, Q., Cotton, R., Crewell, S., Delanoë, J.,
Dörnbrack, A., Ehrlich, A., Ewald, F., Fix, A., Grams, C. M., Gray, S. L., Grob, H., Groß, S., Hagen, M., Harvey, B., Hirsch, L., Jacob, M.,
Kölling, T., Konow, H., Lemmerz, C., Lux, O., Magnusson, L., Mayer, B.,
Mech, M., Moore, R., Pelon, J., Quinting, J., Rahm, S., Rapp, M., Rautenhaus,
M., Reitebuch, O., Reynolds, C. A., Sodemann, H., Spengler, T., Vaughan, G.,
Wendisch, M., Wirth, M., Witschas, B., Wolf, K., and Zinner, T.: The North
Atlantic Waveguide and Downstream Impact Experiment, B. Am. Meteorol. Soc., 99, 1607–1637, https://doi.org/10.1175/BAMS-D-17-0003.1, 2018. a, b, c, d
Scherrer, S. C., Croci-Maspoli, M., Schwierz, C., and Appenzeller, C.:
Two-dimensional indices of atmospheric blocking and their statistical
relationship with winter climate patterns in the Euro-Atlantic region, Int.
J. Climatol., 26, 233–249, https://doi.org/10.1002/joc.1250, 2006. a
Schwierz, C., Croci-Maspoli, M., and Davies, H. C.: Perspicacious indicators
of atmospheric blocking, Geophys. Res. Lett., 31, 0094–8276,
https://doi.org/10.1029/2003GL019341, 2004a. a, b, c, d
Schwierz, C., Dirren, S., and Davies, H. C.: Forced Waves on a Zonally Aligned Jet Stream, J. Atmos. Sci., 61, 73–87,
https://doi.org/10.1175/1520-0469(2004)061<0073:FWOAZA>2.0.CO;2, 2004b. a
Spreitzer, E., Attinger, R., Boettcher, M., Forbes, R., Wernli, H., and Joos,
H.: Modification of potential vorticity near the tropopause by non-conservative processes in the ECMWF model, J. Atmos. Sci., 76, 1709–1726, 2019. a
Sprenger, M. and Wernli, H.: The LAGRANTO Lagrangian analysis tool – version 2.0, Geosci. Model Dev., 8, 2569–2586, https://doi.org/10.5194/gmd-8-2569-2015, 2015. a, b
Steinfeld, D.: ConTrack – Contour Tracking, available at: https://github.com/steidani/ConTrack, last access: August 2020. a
Stoelinga, M. T.: A Potential Vorticity-Based Study of the Role of Diabatic
Heating and Friction in a Numerically Simulated Baroclinic Cyclone, Mon.
Weather Rev., 124, 849–874,
https://doi.org/10.1175/1520-0493(1996)124<0849:APVBSO>2.0.CO;2, 1996. a, b, c, d
Teubler, F. and Riemer, M.: Dynamics of Rossby wave packets in a quantitative
potential vorticity-potential temperature framework, J. Atmos. Sci., 73,
1063–1081, https://doi.org/10.1175/JAS-D-15-0162.1, 2016. a
Tibaldi, S. and Molteni, F.: On the operational predictability of blocking,
Tellus A, 42, 343–365, https://doi.org/10.1034/j.1600-0870.1990.t01-2-00003.x, 1990. a
Tiedtke, M.: A comprehensive mass flux scheme for cumulus parameterization in
large-scale models, Mon. Weather Rev., 117, 1779–1800,
https://doi.org/10.1175/1520-0493(1989)117<1779:ACMFSF>2.0.CO;2, 1989. a
Tiedtke, M.: Representation of clouds in large-scale models, Mon. Weather
Rev., 121, 3040–3061, https://doi.org/10.1175/1520-0493(1993)121<3040:ROCILS>2.0.CO;2,
1993. a
Tyrlis, E. and Hoskins, B. J.: The morphology of Northern Hemisphere blocking, J. Atmos. Sci., 65, 1653–1665, https://doi.org/10.1175/2007JAS2338.1, 2008. a
Wernli, H.: A Lagrangian-based analysis of extratropical cyclones. II: a
detailed case-study, Q. J. Roy. Meteorol. Soc., 123, 1677–1706,
https://doi.org/10.1002/qj.49712354211, 1997. a, b
Wirth, V., Riemer, M., Chang, E. K. M., and Martius, O.: Rossby wave packets
on the midlatitude waveguide – a review, Mon. Weather Rev., 146, 1965–2001,
https://doi.org/10.1175/MWR-D-16-0483.1, 2018.
a
Woollings, T., Barriopedro, D., Methven, J., Son, S.-W., Martius, O., Harvey,
B., Sillmann, J., Lupo, A. R., and Seneviratne, S.: Blocking and its response to climate change, Curr. Clim. Change Rep., 4, 287–300,
https://doi.org/10.1007/s40641-018-0108-z, 2018. a, b, c
Yamazaki, A. and Itoh, H.: Vortex – Vortex interactions for the maintenance of blocking. Part I: the selective absorption mechanism and a case study, J.
Atmos. Sci., 70, 725–742, https://doi.org/10.1175/JAS-D-11-0295.1, 2012.
a, b, c
Zhang, G. and Wang, Z.: North Atlantic extratropical Rossby wave breaking
during the warm season: wave life cycle and role of diabatic heating, Mon.
Weather Rev., 146, 695–712, https://doi.org/10.1175/MWR-D-17-0204.1, 2018. a, b
Zschenderlein, P., Pfahl, S., Wernli, H., and Fink, A. H.: A Lagrangian
analysis of upper-tropospheric anticyclones associated with heat waves in
Europe, Weather Clim. Dynam., 1, 191–206, https://doi.org/10.5194/wcd-1-191-2020, 2020. a
Short summary
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.
The effect of latent heating on atmospheric blocking is investigated using numerical sensitivity...
