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- Summertime changes in climate extremes over the peripheral Arctic regions
after a sudden sea ice retreat Abstract: Summertime changes in climate extremes over the peripheral Arctic regions after a sudden sea ice retreat Steve Delhaye, Thierry Fichefet, François Massonnet, David Docquier, Rym Msadek, Svenya Chripko, Christopher Roberts, Sarah Keeley, and Retish Senan Weather Clim. Dynam., 3, 555–573, https://doi.org/10.5194/wcd-3-555-2022, 2022 It is unclear how the atmosphere will respond to a retreat of summer Arctic sea ice. Much attention has been paid so far to weather extremes at mid-latitude and in winter. Here we focus on the changes in extremes in surface air temperature and precipitation over the Arctic regions in summer during and following abrupt sea ice retreats. We find that Arctic sea ice loss clearly shifts the extremes in surface air temperature and precipitation over terrestrial regions surrounding the Arctic Ocean. PubDate: Wed, 11 May 2022 04:48:14 +020 DOI: 10.5194/wcd-3-555-2022 2022
- Orographic resolution driving the improvements associated with horizontal
resolution increase in the Northern Hemisphere winter mid-latitudes Abstract: Orographic resolution driving the improvements associated with horizontal resolution increase in the Northern Hemisphere winter mid-latitudes Paolo Davini, Federico Fabiano, and Irina Sandu Weather Clim. Dynam., 3, 535–553, https://doi.org/10.5194/wcd-3-535-2022, 2022 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. PubDate: Tue, 10 May 2022 03:43:28 +020 DOI: 10.5194/wcd-3-535-2022 2022
- The global atmospheric energy transport analysed by a wavelength-based
scale separation Abstract: The global atmospheric energy transport analysed by a wavelength-based scale separation Patrick Johannes Stoll and Rune Grand Graversen Weather Clim. Dynam. Discuss., https//doi.org/10.5194/wcd-2022-26,2022 Preprint under review for WCD (discussion: open, 0 comments) 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 2,000 and 8,000 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 of high importance for transporting energy into the polar regions. PubDate: Tue, 10 May 2022 03:43:28 +020 DOI: 10.5194/wcd-2022-262022
- Supercell Convective Environments in Spain based on ERA5: Hail and
Non-Hail Differences Abstract: Supercell Convective Environments in Spain based on ERA5: Hail and Non-Hail Differences Carlos Calvo-Sancho, Javier Díaz-Fernández, Yago Martín, Pedro Bolgiani, Mariano Sastre, Juan Jesús González-Alemán, Daniel Santos-Muñoz, José Ignacio Farrán, and María Luisa Martín Weather Clim. Dynam. Discuss., https//doi.org/10.5194/wcd-2022-27,2022 Preprint under review for WCD (discussion: open, 0 comments) Supercells are amongst the most complex and dangerous severe convective storms due to their associated phenomena (lightning, strong winds, large hail, flash-floods, or tornadoes). In this survey we study the supercell synoptic configurations and convective environments in Spain using the atmospheric reanalysis ERA5. Moreover, supercells are grouped in hail (greater than 5 cm) and non-hail events in order to compare and analyze both groups. The results reveals statistical significant differences. PubDate: Tue, 03 May 2022 11:23:53 +020 DOI: 10.5194/wcd-2022-272022
- Classification of Alpine South Foehn based on five years of km-scale
analysis data Abstract: Classification of Alpine South Foehn based on five years of km-scale analysis data Lukas Jansing, Lukas Papritz, Bruno Dürr, Daniel Gerstgrasser, and Michael Sprenger Weather Clim. Dynam. Discuss., https//doi.org/10.5194/wcd-2022-24,2022 Preprint under review for WCD (discussion: open, 0 comments) This study presents a five-year climatology of three main Foehn types and three Deep Foehn subtypes. The main types differ in the large-scale and Alpine-scale weather conditions, the subtypes in terms of the amount and extent of precipitation on the Alpine south side. They are found to strongly affect the local meteorological characteristics at Altdorf. The study concludes by setting the new classification into a historic context. PubDate: Mon, 02 May 2022 11:23:53 +020 DOI: 10.5194/wcd-2022-242022
- Predictability of a tornado environment index from ENSO and the Arctic
Oscillation Abstract: Predictability of a tornado environment index from ENSO and the Arctic Oscillation Michael K. Tippett, Chiara Lepore, and Michelle L. L'Heureux Weather Clim. Dynam. Discuss., https//doi.org/10.5194/wcd-2022-25,2022 Preprint under review for WCD (discussion: open, 0 comments) The El Nino-Southern Oscillation (ENSO) and Arctic Oscillation (AO) are phenomena that affect the weather and climate of North America. Although ENSO harkens from the tropical Pacific and the AO high above the North Pole–the spatial patterns of their influence on a North American tornado environment index are remarkably similar in computer models. We find that when ENSO and the AO act in concert, their impact is large, and when they oppose each other their impact is small. PubDate: Thu, 21 Apr 2022 18:06:02 +020 DOI: 10.5194/wcd-2022-252022
- Quantifying climate model representation of the wintertime Euro-Atlantic
circulation using geopotential-jet regimes Abstract: Quantifying climate model representation of the wintertime Euro-Atlantic circulation using geopotential-jet regimes Joshua Dorrington, Kristian Strommen, and Federico Fabiano Weather Clim. Dynam., 3, 505–533, https://doi.org/10.5194/wcd-3-505-2022, 2022 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. PubDate: Wed, 20 Apr 2022 18:06:02 +020 DOI: 10.5194/wcd-3-505-2022 2022
- Signatures of midlatitude heat waves in global Rossby wave spectra
Abstract: Signatures of midlatitude heat waves in global Rossby wave spectra Iana Strigunova, Richard Blender, Frank Lunkeit, and Nedjeljka Žagar Weather Clim. Dynam. Discuss., https//doi.org/10.5194/wcd-2022-23,2022 Preprint under review for WCD (discussion: open, 0 comments) Extreme events like heat waves are accompanied by changes in atmospheric circulation across scales. Our study shows that heat waves over Eurasia have fingerprints in the probability density functions (PDFs) of the global balanced energy. We analyzed energy anomalies in the global balanced circulation and its components (the zonal mean state and Rossby waves at different zonal scales) and found an increase in the skewness of the PDFs of the planetary scale Rossby waves during surface heat waves. PubDate: Tue, 19 Apr 2022 18:06:02 +020 DOI: 10.5194/wcd-2022-232022
- Extreme Atlantic hurricane seasons made twice as likely by ocean warming
Abstract: Extreme Atlantic hurricane seasons made twice as likely by ocean warming Peter Pfleiderer, Shruti Nath, and Carl-Friedrich Schleussner Weather Clim. Dynam., 3, 471–482, https://doi.org/10.5194/wcd-3-471-2022, 2022 Tropical cyclones are amongst the most dangerous weather events. Here we develop an empirical model that allows us to estimate the number and strengths of tropical cyclones for given atmospheric conditions and sea surface temperatures. An application of the model shows that atmospheric circulation is the dominant factor for seasonal tropical cyclone activity. However, warming sea surface temperatures have doubled the likelihood of extremely active hurricane seasons in the past decades. PubDate: Wed, 13 Apr 2022 15:59:38 +020 DOI: 10.5194/wcd-3-471-2022 2022
- A global climatology of polar lows investigated for local differences and
wind-shear environments Abstract: A global climatology of polar lows investigated for local differences and wind-shear environments Patrick Johannes Stoll Weather Clim. Dynam., 3, 483–504, https://doi.org/10.5194/wcd-3-483-2022, 2022 Polar lows are small but intense cyclones and constitute one of the major natural hazards in the polar regions. To be aware of when and where polar lows occur, this study maps polar lows globally by utilizing new atmospheric datasets. Polar lows develop in all marine areas adjacent to sea ice or cold landmasses, mainly in the winter half year. The highest frequency appears in the Nordic Seas. Further, it is found that polar lows are rather similar in the different ocean sub-basins. PubDate: Mon, 11 Apr 2022 15:59:38 +020 DOI: 10.5194/wcd-3-483-2022 2022
- Circumglobal Rossby wave patterns during boreal winter highlighted by
space–time spectral analysis Abstract: Circumglobal Rossby wave patterns during boreal winter highlighted by space–time spectral analysis 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, 2022 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. PubDate: Fri, 08 Apr 2022 10:22:28 +020 DOI: 10.5194/wcd-3-449-2022 2022
- Dynamics of Gap Winds in the Great Rift Valley, Ethiopia: Emphasis on
Strong Winds at Lake Abaya Abstract: Dynamics of Gap Winds in the Great Rift Valley, Ethiopia: Emphasis on Strong Winds at Lake Abaya Cornelius Immanuel Weiß, Alexander Gohm, Mathias Walter Rotach, and Thomas Torora Minda Weather Clim. Dynam. Discuss., https//doi.org/10.5194/wcd-2022-20,2022 Preprint under review for WCD (discussion: open, 0 comments) Two gap flow events in the Great Rift Valley in Ethiopia were investigated with observations, ERA5 reanalysis data and simulations with the numerical weather prediction model WRF. The main focus was on strong winds in the area around Lake Abaya since the winds may generate waves on the lake which help to sustain the lakes ecology. That is important in terms of food supply for the local population. The gap winds exhibit a diurnal cycle and a seasonal dependence. PubDate: Thu, 07 Apr 2022 10:22:28 +020 DOI: 10.5194/wcd-2022-202022
- Tropical influence on heat-generating atmospheric circulation over
Australia strengthens through spring Abstract: Tropical influence on heat-generating atmospheric circulation over Australia strengthens through spring Roseanna C. McKay, Julie M. Arblaster, and Pandora Hope Weather Clim. Dynam., 3, 413–428, https://doi.org/10.5194/wcd-3-413-2022, 2022 Understanding what makes it hot in Australia in spring helps us better prepare for harmful impacts. We look at how the higher latitudes and tropics change the atmospheric circulation from early to late spring and how that changes maximum temperatures in Australia. We find that the relationship between maximum temperatures and the tropics is stronger in late spring than early spring. These findings could help improve forecasts of hot months in Australia in spring. PubDate: Tue, 05 Apr 2022 16:07:24 +020 DOI: 10.5194/wcd-3-413-2022 2022
- Future changes in North Atlantic winter cyclones in CESM-LE – Part 1:
Cyclone intensity, potential vorticity anomalies, and horizontal wind speed Abstract: Future changes in North Atlantic winter cyclones in CESM-LE – Part 1: Cyclone intensity, potential vorticity anomalies, and horizontal wind speed Edgar Dolores-Tesillos, Franziska Teubler, and Stephan Pfahl Weather Clim. Dynam., 3, 429–448, https://doi.org/10.5194/wcd-3-429-2022, 2022 Strong winds caused by extratropical cyclones represent a costly hazard for European countries. Here, based on CESM-LENS coupled climate simulations, we show that future changes of such strong winds are characterized by an increased magnitude and extended footprint southeast of the cyclone center. This intensification is related to a combination of increased diabatic heating and changes in upper-level wave dynamics. PubDate: Tue, 05 Apr 2022 16:07:24 +020 DOI: 10.5194/wcd-3-429-2022 2022
- How intense daily precipitation depends on temperature and the occurrence
of specific weather systems – an investigation with ERA5 reanalyses in the extratropical Northern Hemisphere Abstract: How intense daily precipitation depends on temperature and the occurrence of specific weather systems – an investigation with ERA5 reanalyses in the extratropical Northern Hemisphere Philipp Zschenderlein and Heini Wernli Weather Clim. Dynam., 3, 391–411, https://doi.org/10.5194/wcd-3-391-2022, 2022 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. PubDate: Mon, 04 Apr 2022 16:07:24 +020 DOI: 10.5194/wcd-3-391-2022 2022
- Stratospheric Wave Reflection Events Modulate North American Weather
Regimes and Cold Spells Abstract: Stratospheric Wave Reflection Events Modulate North American Weather Regimes and Cold Spells Gabriele Messori, Marlene Kretschmer, Simon H. Lee, and Vivien Matthias Weather Clim. Dynam. Discuss., https//doi.org/10.5194/wcd-2022-18,2022 Preprint under review for WCD (discussion: open, 0 comments) Over 10 km above the ground, there is a region of the atmosphere called stratosphere. While there is very little air in the stratosphere itself, its interactions with the lower parts of the atmosphere – where we live – can affect the weather. Here we study a specific example of such interaction, whereby processes occurring at the boundary of the stratosphere can lead to a continent-wide drop in temperatures in North America during winter. PubDate: Mon, 04 Apr 2022 16:07:24 +020 DOI: 10.5194/wcd-2022-182022
- Impact of climate change on wintertime European atmospheric blocking
Abstract: Impact of climate change on wintertime European atmospheric blocking Sara Bacer, Fatima Jomaa, Julien Beaumet, Hubert Gallée, Enzo Le Bouëdec, Martin Ménégoz, and Chantal Staquet Weather Clim. Dynam., 3, 377–389, https://doi.org/10.5194/wcd-3-377-2022, 2022 We study the impact of climate change on wintertime atmospheric blocking over Europe. We focus on the frequency, duration, and size of blocking events. The blocking events are identified via the weather type decomposition methodology. We find that blocking frequency, duration, and size are mostly stationary over the 21st century. Additionally, we compare the blocking size results with the size of the blocking events identified via a different approach using a blocking index. PubDate: Fri, 01 Apr 2022 16:07:24 +020 DOI: 10.5194/wcd-3-377-2022 2022
- Differentiating lightning in winter and summer with characteristics of the
wind field and mass field Abstract: Differentiating lightning in winter and summer with characteristics of the wind field and mass field 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, 2022 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. PubDate: Thu, 31 Mar 2022 16:07:24 +020 DOI: 10.5194/wcd-3-361-2022 2022
- Future changes in the extratropical storm tracks and cyclone intensity,
wind speed, and structure Abstract: Future changes in the extratropical storm tracks and cyclone intensity, wind speed, and structure Matthew D. K. Priestley and Jennifer L. Catto Weather Clim. Dynam., 3, 337–360, https://doi.org/10.5194/wcd-3-337-2022, 2022 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 %. PubDate: Thu, 31 Mar 2022 16:07:24 +020 DOI: 10.5194/wcd-3-337-2022 2022
- Trends in the tropospheric general circulation from 1979 to 2022
Abstract: Trends in the tropospheric general circulation from 1979 to 2022 Adrian John Simmons Weather Clim. Dynam. Discuss., https//doi.org/10.5194/wcd-2022-19,2022 Preprint under review for WCD (discussion: open, 0 comments) This study of changes in temperature and wind since 1979 met its twin aims of (i) increasing confidence in some findings of the latest IPCC assessment and (ii) identifying changes that had received little or no previous attention. It reports a small overall intensification and shift in position of the North Atlantic jet stream and associated storms, and a strengthening of tropical upper-level easterlies. Increases in low-level winds over tropical and southern hemispheric oceans are confirmed. PubDate: Thu, 31 Mar 2022 16:07:24 +020 DOI: 10.5194/wcd-2022-192022
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