Twenty‐First‐Century Changes in the Eastern Mediterranean Etesians and Associated Midlatitude Atmospheric Circulation. Issue 23 (9th December 2019)

• Record Type: Journal Article
• Authors: Dafka, Stella; Toreti, Andrea; Zanis, Prodromos; Xoplaki, Elena; Luterbacher, Juerg
• Is Part Of: Journal of geophysical research. Volume 124:Issue 23(2019)
• Page Start: 12741
• Page End: 12754
• Publication Date: 2019-12-09
• Subjects: Etesians -- extreme winds -- Eastern Mediterranean -- midlatitude atmospheric circulation -- EURO‐CORDEX -- future projections; Atmospheric physics -- Periodicals; Geophysics -- Periodicals; 551.5
• DOI: 10.1029/2019JD031203
• Languages: English
• ISSNs: 2169-897X

Abstract

Abstract: The Etesians are the dominant synoptically driven winds observed in the Eastern Mediterranean, usually from late spring to late summer. Due to the complex topography, the Etesians can be very strong and pose significant environmental hazards, especially over wildfire incidents. This study assesses the impacts of climate change on future Etesians by analyzing the response of the most recent EURO‐CORDEX regional climate simulations at the 12‐km grid resolution over the twenty‐first century. The mean model ensemble projects a significant increase of the Etesians' frequency and intensity under the two emission scenarios RCP4.5 and RCP8.5. This response is connected to an increase in the zonal wind at 200 hPa, a reinforcement of the midlatitude westerly flow, and a decrease in the wave amplitude. These circulation changes accelerate the mid‐to‐high latitude eastward propagation of the large‐scale circulation systems which can favor enhanced ridges over the Balkans. A strengthening and poleward shift of the subtropical jet stream is also projected, connected with stronger subsidence over the Eastern Mediterranean. The projected changes will have profound environmental and societal implications, including the lengthening of the wildfire season and increasing air pollution risk in the region. On the other hand, the current estimate of future wind power potential in the Aegean Sea will be significantly increased by the end of the century, which might have positive impact in the regional economy. Plain Language Summary: The Etesians are one of the most prominent wind systems in the world. They are persistent, northerly, regional‐scale winds that blow every summer over the Aegean Sea and the Eastern Mediterranean. They are known since antiquity, with the first reference dating back to the eighth century B.C. Recent studies based on climate model projections have pointed to a decrease in the wind speed in most of Europe for the coming decades, except for the Aegean Sea. Thus, this study assesses the impacts of climate change on Etesians and identifies the associated dynamical mechanisms. The main findings show an increase in the Etesians' frequency and intensity over the twenty‐first century mainly attributable to changes in the large‐scale atmospheric circulation. The projected changes will have profound societal and environmental implications in response to the associated lengthening of the wildfire season and the increased risk of air pollution in the region. At the same time, a positive impact on the regional economy due to the increase in wind power potential is also expected. Key Points: The impacts of large‐scale atmospheric circulation changes in the Eastern Mediterranean winds over the twenty‐first century is here assessed Projections show a reinforced westerly flow, a decreased meridional wave amplitude, and an intensified‐poleward shifted Subtropical Jetstream A progressively increase of Etesians frequency and intensity induced by large‐scale circulation processes is projected for the twenty‐first century