Impact of climate change on the climatology of Vb cyclones

Abstract

Extratropical cyclones of type Vb develop over the western Mediterranean and move north-eastward, leading to heavy precipitation over central Europe and posing a major natural hazard. Thus, this study aims at assessing their sensitivity to climate change and deepens the understanding of the underlying processes of Vbtype cyclones. The analysis is based on global climate model output, which is dynamically downscaled for extreme Vb cyclones. Thereby two periods are compared: the reference period 1979 to 2013, and the future period 2070 to 2099 under the representative concentration pathway RCP8.5. Additionally, we include the analysis from a large ensemble (LENS), where 25 ensemble members are analysed for the reference period 1990-2005 and the future period 2071-2080. The results show a reduction of Vb cyclones from 3.2 events per year during the reference period to only 2.1 Vb cyclones per year at the end of the 21st century. This result is supported by the LENS, which shows a significant reduction from 2.9 to 2.6 Vb events per year. This reduction is induced by a northward shift of cyclone track over Europe in the future. To gain insight into the impact of Vb cyclones, 10 Vb cyclones with the most intense precipitation over the Alps are selected and dynamically downscaled for each period, separately. Although the overall precipitation in the innermost domain stays the same in the two periods, results indicate that future Vb events tend to affect more strongly the eastern coasts of the Mediterranean Sea, while the impact in the Alpine region becomes slightly ameliorated compared to the current conditions. Furthermore, the dynamical downscaling exhibits an increased temperature contrast between the Mediterranean Sea and the European land for these 10 events in future. This contrast leads to a higher instability at coastal areas and thus explains the changed precipitation pattern.

Wind Waves in the Mediterranean Sea: An ERA5 Reanalysis Wind-Based Climatology

“…Hence, the reasons for different trends on the intensity of storms should be searched for in the wind forcings that have generated the wave model results. Changes in ERA5 wind characteristics might be due, for instance, to changes in storm trajectories, as suggested by numerous climatological studies, which investigated not only the intensity and frequency of Mediterranean cyclones but also the variability of their trajectories in the last decades and in the future climate projections (Lionello et al, 2002;Lionello and Giorgi, 2007;Cavicchia et al, 2014;Messmer et al, 2020). We have verified monthly H s percentile trends from the ERA5 wind forced wave hindcast at the MS basin scale against trends from satellite altimeters and found a general agreement in the increasing/decreasing trends as well as in the magnitude of the trends.…”

Alarming coastal vulnerability of the deltaic and sandy beaches of North Africa

“…1 A. The global warming impact is to increases the occurrence and intensity of storm surges 25 , 53 . Alternatively, the METEOCEAN Model studies (e.g.…”

Estimation of precipitation induced by tropical cyclones based on machine‐learning‐enhanced analogue identification of numerical prediction

“…Junk et al, 2015) can also be expected to improve the performance of the method. Finally, the current study only uses data at a single level (850 hPa), whereas including the data at several levels could possibly be beneficial for the identification performance (Hofstatter et al, 2016;Messmer et al, 2020).…”