The evolution of the Etesian Winds over the 21st century : Results of CMIP5 model simulations.

Περίληψη

The Etesian winds are northern sector winds of the lower atmosphere that flow over the Aegean Sea during summer and early autumn moderating the summer temperatures and regulating the concentration of pollutants in the SE Mediterranean. This study investigates future projections of the Etesian winds and their possible changes using Earth System Model (ESM) simulations available from the Coupled Model Intercomparison Project Phase 5 (CMIP5), under different Representative Concentration Pathways (RCP), namely RCP2.6, RCP4.5 and RCP8.5 of the Intergovermental Panel on Climate Change (IPCC). Here we use simulations of four ESMs (MPI-ESM-MR, MPI-ESM-LR, HadGEM2-CC, CanESM2 and GFDLHIRAM-C360_amip) which provide data for RCPs scenarios. For the detection of days with etesian winds during the summer months of July and August we used the amplitude and the direction of the winds over the Aegean Sea. The models’ ability to simulate realistic etesian winds frequency is evaluated using the CMIP5 historical simulations (1950-2005) and comparing results to the ERA-Interim reanalysis and the L-days index according to Karapiperis (1951). Finally we examined the future development and change of the amplitude, frequency and the seasonal dependence of the etesian winds using climate data projections during 2006-2100 according to IPCC scenarios for three periods (2010-2039, 2040-2069 and 2070-2100). Under the RCP2.6 scenario changes in the Etesian days frequency are insignificant, whereas with the RCP4.5 and RCP8.5 our analysis shows an increase in the number of etesian wind days towards the end of the 21st century, especially during the last 30 years.