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- Atmospheric response to cold wintertime Tibetan Plateau conditions over
eastern Asia in climate models Abstract: Atmospheric response to cold wintertime Tibetan Plateau conditions over eastern Asia in climate models 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, 2023 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. PubDate: Fri, 15 Sep 2023 10:41:25 +020 DOI: 10.5194/wcd-4-809-2023 2023
- A critical evaluation of decadal solar cycle imprints in the MiKlip
historical ensemble simulations Abstract: A critical evaluation of decadal solar cycle imprints in the MiKlip historical ensemble simulations Tobias C. Spiegl, Ulrike Langematz, Holger Pohlmann, and Jürgen Kröger Weather Clim. Dynam., 4, 789–807, https://doi.org/10.5194/wcd-4-789-2023, 2023 We investigate the role of the solar cycle in atmospheric domains with the Max Plank Institute Earth System Model in high resolution (MPI-ESM-HR). We focus on the tropical upper stratosphere, Northern Hemisphere (NH) winter dynamics and potential surface imprints. We found robust solar signals at the tropical stratopause and a weak dynamical response in the NH during winter. However, we cannot confirm the importance of the 11-year solar cycle for decadal variability in the troposphere. PubDate: Mon, 11 Sep 2023 10:41:25 +020 DOI: 10.5194/wcd-4-789-2023 2023
- Classification of large-scale environments that drive the formation of
mesoscale convective systems over southern West Africa Abstract: Classification of large-scale environments that drive the formation of mesoscale convective systems over southern West Africa Francis Nkrumah, Cornelia Klein, Kwesi Akumenyi Quagraine, Rebecca Berkoh-Oforiwaa, Nana Ama Browne Klutse, Patrick Essien, Gandomè Mayeul Leger Davy Quenum, and Hubert Azoda Koffi Weather Clim. Dynam., 4, 773–788, https://doi.org/10.5194/wcd-4-773-2023, 2023 It is not yet clear which variations in broader atmospheric conditions of the West African monsoon may lead to mesoscale convective system (MCS) occurrences in southern West Africa (SWA). In this study, we identified nine different weather patterns and categorized them as dry-, transition-, or monsoon-season types using a method called self-organizing maps (SOMs). It was revealed that a warmer Sahel region can create favourable conditions for MCS formation in SWA. PubDate: Wed, 06 Sep 2023 21:38:52 +020 DOI: 10.5194/wcd-4-773-2023 2023
- The importance of regional sea-ice variability for the coastal climate and
near-surface temperature gradients in Northeast Greenland Abstract: The importance of regional sea-ice variability for the coastal climate and near-surface temperature gradients in Northeast Greenland Sonika Shahi, Jakob Abermann, Tiago Silva, Kirsty Langley, Signe Hillerup Larsen, Mikhail Mastepanov, and Wolfgang Schöner Weather Clim. Dynam., 4, 747–771, https://doi.org/10.5194/wcd-4-747-2023, 2023 This study highlights how the sea ice variability in the Greenland Sea affects the terrestrial climate and the surface mass changes of peripheral glaciers of the Zackenberg region (ZR), Northeast Greenland, combining model output and observations. Our results show that the temporal evolution of sea ice influences the climate anomaly magnitude in the ZR. We also found that the changing temperature and precipitation patterns due to sea ice variability can affect the surface mass of the ice cap. PubDate: Fri, 01 Sep 2023 17:44:19 +020 DOI: 10.5194/wcd-4-747-2023 2023
- Adverse impact of terrain steepness on thermally driven initiation of
orographic convection Abstract: Adverse impact of terrain steepness on thermally driven initiation of orographic convection Matthias Göbel, Stefano Serafin, and Mathias W. Rotach Weather Clim. Dynam., 4, 725–745, https://doi.org/10.5194/wcd-4-725-2023, 2023 On summer days over mountains, upslope winds transport moist air towards mountain tops and beyond, making local rain showers more likely. We use idealized simulations to investigate how mountain steepness affects this mechanism. We find that steeper mountains lead to a delayed onset and lower intensity of the storms, because less moisture accumulates over the ridges and the thermal updraft zone at the top is narrower and thus more prone to the intrusion of dry air from the environment. PubDate: Thu, 31 Aug 2023 17:44:19 +020 DOI: 10.5194/wcd-4-725-2023 2023
- Validation of boreal summer tropical–extratropical causal links in
seasonal forecasts Abstract: Validation of boreal summer tropical–extratropical causal links in seasonal forecasts Giorgia Di Capua, Dim Coumou, Bart van den Hurk, Antje Weisheimer, Andrew G. Turner, and Reik V. Donner Weather Clim. Dynam., 4, 701–723, https://doi.org/10.5194/wcd-4-701-2023, 2023 Heavy rainfall in tropical regions interacts with mid-latitude circulation patterns, and this interaction can explain weather patterns in the Northern Hemisphere during summer. In this analysis we detect these tropical–extratropical interaction pattern both in observational datasets and data obtained by atmospheric models and assess how well atmospheric models can reproduce the observed patterns. We find a good agreement although these relationships are weaker in model data. PubDate: Mon, 14 Aug 2023 12:36:36 +020 DOI: 10.5194/wcd-4-701-2023 2023
- Transient anticyclonic eddies and their relationship to atmospheric block
persistence Abstract: Transient anticyclonic eddies and their relationship to atmospheric block persistence 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, 2023 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. PubDate: Tue, 08 Aug 2023 14:19:40 +020 DOI: 10.5194/wcd-4-683-2023 2023
- On the linkage between future Arctic sea ice retreat, Euro-Atlantic
circulation regimes and temperature extremes over Europe Abstract: On the linkage between future Arctic sea ice retreat, Euro-Atlantic circulation regimes and temperature extremes over Europe Johannes Riebold, Andy Richling, Uwe Ulbrich, Henning Rust, Tido Semmler, and Dörthe Handorf Weather Clim. Dynam., 4, 663–682, https://doi.org/10.5194/wcd-4-663-2023, 2023 Arctic sea ice loss might impact the atmospheric circulation outside the Arctic and therefore extremes over mid-latitudes. Here, we analyze model experiments to initially assess the influence of sea ice loss on occurrence frequencies of large-scale circulation patterns. Some of these detected circulation changes can be linked to changes in occurrences of European temperature extremes. Compared to future global temperature increases, the sea-ice-related impacts are however of secondary relevance. PubDate: Mon, 31 Jul 2023 13:28:00 +020 DOI: 10.5194/wcd-4-663-2023 2023
- A composite approach to produce reference datasets for extratropical
cyclone tracks: application to Mediterranean cyclones Abstract: A composite approach to produce reference datasets for extratropical cyclone tracks: application to Mediterranean cyclones 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, 2023 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. PubDate: Fri, 21 Jul 2023 14:20:37 +020 DOI: 10.5194/wcd-4-639-2023 2023
- The role of boundary layer processes in summer-time Arctic cyclones
Abstract: The role of boundary layer processes in summer-time Arctic cyclones Hannah L. Croad, John Methven, Ben Harvey, Sarah P. E. Keeley, and Ambrogio Volonté Weather Clim. Dynam., 4, 617–638, https://doi.org/10.5194/wcd-4-617-2023, 2023 The interaction between Arctic cyclones and the sea ice surface in summer is investigated by analysing the friction and sensible heat flux processes acting in two cyclones with contrasting evolution. The major finding is that the effects of friction on cyclone strength are dependent on a particular feature of cyclone structure: whether they have a warm or cold core during growth. Friction leads to cooling within both cyclone types in the lower atmosphere, which may contribute to their longevity. PubDate: Tue, 18 Jul 2023 18:32:36 +020 DOI: 10.5194/wcd-4-617-2023 2023
- Uncertainty growth and forecast reliability during extratropical
cyclogenesis Abstract: Uncertainty growth and forecast reliability during extratropical cyclogenesis Mark J. Rodwell and Heini Wernli Weather Clim. Dynam., 4, 591–615, https://doi.org/10.5194/wcd-4-591-2023, 2023 Midlatitude storms and their downstream impacts have a major impact on society, yet their prediction is especially prone to uncertainty. While this can never be fully eliminated, we find that the initial rate of growth of uncertainty varies for a range of forecast models. Examination of the model of the European Centre for Medium-Range Weather Forecasts (ECMWF) suggests ways in which uncertainty growth could be reduced, leading to sharper and more reliable forecasts over the first few days. PubDate: Wed, 05 Jul 2023 18:32:36 +020 DOI: 10.5194/wcd-4-591-2023 2023
- The relationship between extra-tropical cyclone intensity and
precipitation in idealised current and future climates Abstract: The relationship between extra-tropical cyclone intensity and precipitation in idealised current and future climates Victoria A. Sinclair and Jennifer L. Catto Weather Clim. Dynam., 4, 567–589, https://doi.org/10.5194/wcd-4-567-2023, 2023 We studied the relationship between the strength of mid-latitude cyclones and their precipitation, how this may change in the future, and whether it depends of the type of cyclone. The relationship between cyclone strength and precipitation increases in warmer climates and depends strongly on the type of cyclone. For some cyclone types there is no relation between cyclone strength and precipitation. For all cyclone types, precipitation increases with uniform warming and polar amplification. PubDate: Tue, 04 Jul 2023 18:32:36 +020 DOI: 10.5194/wcd-4-567-2023 2023
- Convection-parameterized and convection-permitting modelling of heavy
precipitation in decadal simulations of the greater Alpine region with COSMO-CLM Abstract: Convection-parameterized and convection-permitting modelling of heavy precipitation in decadal simulations of the greater Alpine region with COSMO-CLM Alberto Caldas-Alvarez, Hendrik Feldmann, Etor Lucio-Eceiza, and Joaquim G. Pinto Weather Clim. Dynam., 4, 543–565, https://doi.org/10.5194/wcd-4-543-2023, 2023 We evaluate convection-permitting modelling (CPM) simulations for the greater Alpine area to assess its added value compared to a 25 km resolution. A new method for severe precipitation detection is used, and the associated synoptic weather types are considered. Our results document the added value of CPM for precipitation representation with higher intensities, better rank correlation, better hit rates, and an improved amount and structure, but with an overestimation of the rates. PubDate: Fri, 23 Jun 2023 16:58:57 +020 DOI: 10.5194/wcd-4-543-2023 2023
- Large uncertainty in observed estimates of tropical width from the
meridional stream function Abstract: Large uncertainty in observed estimates of tropical width from the meridional stream function Daniel Baldassare, Thomas Reichler, Piret Plink-Björklund, and Jacob Slawson Weather Clim. Dynam., 4, 531–541, https://doi.org/10.5194/wcd-4-531-2023, 2023 Using ensemble members from the ERA5 reanalysis, the most widely used method for estimating tropical-width trends, the meridional stream function, was found to have large error, particularly in the Northern Hemisphere and in the summer, because of weak gradients at the tropical edge and poor data quality. Another method, using the latitude where the surface wind switches from westerly to easterly, was found to have lower error due to better-observed data. PubDate: Thu, 22 Jun 2023 16:58:57 +020 DOI: 10.5194/wcd-4-531-2023 2023
- Future changes in the mean and variability of extreme rainfall indices
over the Guinea coast and role of the Atlantic equatorial mode Abstract: Future changes in the mean and variability of extreme rainfall indices over the Guinea coast and role of the Atlantic equatorial mode Koffi Worou, Thierry Fichefet, and Hugues Goosse Weather Clim. Dynam., 4, 511–530, https://doi.org/10.5194/wcd-4-511-2023, 2023 The Atlantic equatorial mode (AEM) of variability is partly responsible for the year-to-year rainfall variability over the Guinea coast. We used the current climate models to explore the present-day and future links between the AEM and the extreme rainfall indices over the Guinea coast. Under future global warming, the total variability of the extreme rainfall indices increases over the Guinea coast. However, the future impact of the AEM on extreme rainfall events decreases over the region. PubDate: Wed, 14 Jun 2023 18:08:23 +020 DOI: 10.5194/wcd-4-511-2023 2023
- Understanding Winter Windstorm Predictability over Europe
Abstract: Understanding Winter Windstorm Predictability over Europe Lisa Degenhardt, Gregor C. Leckebusch, and Adam A. Scaife Weather Clim. Dynam. Discuss., https//doi.org/10.5194/wcd-2023-12,2023 Preprint under review for WCD (discussion: open, 0 comments) This study is investigating how dynamical factors that are known to influence cyclone or windstorm development and strengthening also influence the seasonal forecast skill of severe winter windstorms. This study shows which factors are well represented in the seasonal forecast model, GloSea5, and which might would need improvement to might improve the forecast of severe winter windstorms. PubDate: Thu, 01 Jun 2023 14:09:03 +020 DOI: 10.5194/wcd-2023-122023
- Thunderstorm environments in Europe
Abstract: Thunderstorm environments in Europe 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, 2023 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. PubDate: Thu, 25 May 2023 18:22:30 +020 DOI: 10.5194/wcd-4-489-2023 2023
- The teleconnection of extreme El Niño–Southern Oscillation (ENSO)
events to the tropical North Atlantic in coupled climate models Abstract: The teleconnection of extreme El Niño–Southern Oscillation (ENSO) events to the tropical North Atlantic in coupled climate models Jake W. Casselman, Joke F. Lübbecke, Tobias Bayr, Wenjuan Huo, Sebastian Wahl, and Daniela I. V. Domeisen Weather Clim. Dynam., 4, 471–487, https://doi.org/10.5194/wcd-4-471-2023, 2023 El Niño–Southern Oscillation (ENSO) has remote effects on the tropical North Atlantic (TNA), but the connections' nonlinearity (strength of response to an increasing ENSO signal) is not always well represented in models. Using the Community Earth System Model version 1 – Whole Atmosphere Community Climate Mode (CESM-WACCM) and the Flexible Ocean and Climate Infrastructure version 1, we find that the TNA responds linearly to extreme El Niño but nonlinearly to extreme La Niña for CESM-WACCM. PubDate: Mon, 22 May 2023 18:22:30 +020 DOI: 10.5194/wcd-4-471-2023 2023
- Model-simulated hydroclimate in the East Asian summer monsoon region
during past and future climate: a pilot study with a moisture source perspective Abstract: Model-simulated hydroclimate in the East Asian summer monsoon region during past and future climate: a pilot study with a moisture source perspective Astrid Fremme, Paul J. Hezel, Øyvind Seland, and Harald Sodemann Weather Clim. Dynam., 4, 449–470, https://doi.org/10.5194/wcd-4-449-2023, 2023 We study the atmospheric moisture transport into eastern China for past, present, and future climate. Hence, we use different climate and weather prediction model data with a moisture source identification method. We find that while the moisture to first order originates mostly from similar regions, smaller changes consistently point to differences in the recycling of precipitation over land between different climates. Some differences are larger between models than between different climates. PubDate: Mon, 15 May 2023 22:24:27 +020 DOI: 10.5194/wcd-4-449-2023 2023
- What distinguishes 100-year precipitation extremes over central European
river catchments from more moderate extreme events' Abstract: What distinguishes 100-year precipitation extremes over central European river catchments from more moderate extreme events' Florian Ruff and Stephan Pfahl Weather Clim. Dynam., 4, 427–447, https://doi.org/10.5194/wcd-4-427-2023, 2023 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. PubDate: Fri, 12 May 2023 07:34:08 +020 DOI: 10.5194/wcd-4-427-2023 2023
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