Assessment of the changes in the Etesians in the EURO-CORDEX regional model projections

The northerly Etesian winds blow persistently over the Aegean Sea and eastern Mediterranean (EM) during summer months (June, July and August). This study investigates the July-August (JA) characteristics of the Etesians for a present time period (1981-2000) from both ECMWF ERA-Interim Reanalysis data set (observations) and 11 EURO-CORDEX regional climate model (RCM) simulations and assesses future changes using the associated RCP8.5 simulations. An EOF analysis applied to observations near surface meridional wind component (v10) over eastern Mediterranean demonstrates its strength as the leading mode, which explains 43.6% of the total variance, as the principal component (PC) time series of EOF1 has a very high correlation (r = 0.98) with an index showing the intensity of the Etesians. A composite analysis involving the opposite phases in the PC time series reveals that the strong Etesians develop when high pressure takes place towards Balkans and the Black Sea, which increases the meridional pressure gradient over the Aegean Sea. Some of the RCMs reproduce quite realistically pressure system and its associated Etesian winds. However, the intensity of the Etesians in these simulations is usually not as high as that in observations despite their higher horizontal resolutions. In general, the Etesians are projected to be stronger in the future periods as a result of the increasing pressure gradient over the Aegean Sea. This result suggests that the wind energy potential of the region that already attracts investment from the energy sector will increase in the future.