DATE2016-06-01 18:02:59
IDABSTRACT20160601180259-1046
CONTACTezber@itu.edu.tr
PRESENTATIONORAL-PLENARY
INVITED0
IDSESSION1
TITLEEFFECT OF EAST ASIAN TROUGH ON THE TEMPERATURE PATTERNS IN THE EURO-MEDITERRANEAN REGION IN THE EARLY SPRING AND THE EXTREME CASE OF THE YEAR 2004
AUTHORSYasemin Ezber (1), Deniz Bozkurt (2), Omer Lutfi Sen (1)
AFFILIATIONS
  1. Istanbul Technical University, Itu Istanbul (Turkey)
  2. University Of Chile Santiago (Chile)
ABSTRACTAnomalous temperatures over eastern Anatolia during the first week of March 2004 caused rapid snowmelt and resulted in high river discharges that are unprecedented in the region at that time of year. The primary objective of the study is to investigate the underlying surface and atmospheric mechanisms leading to this extreme event, together with a long-term analysis using ERA-Interim data. The surface observations showed that the temperatures increased well above 10oC in the region as part of a larger warming pattern extending from northeastern Africa to Caucasus and Caspian regions to Siberia. A counter cooling pattern that extends from Europe to northwestern parts of Africa was also evident. This dipole temperature pattern was produced by a strong trough lying along a tilted axis between central north Africa to eastern Europe. A strong depression over central north Africa helped maintain a cutoff low associated with the trough. A detailed analysis of several teleconnection indices indicated no outstanding signal related with such a strong trough in the first week of March. Albeit not very strong, Arctic Oscillation was in its negative phase indicating the existence of the high-amplitude Rossby Waves in the northern hemisphere. Further analysis reveals that the anomalous strengthening of the East Asian Trough (EAT) increased the amplitudes of ridge-trough system over Euro-Mediterranean region, causing colder polar air to penetrate to interiors of northwestern Africa while warmer African air to reach the higher latitudes along northeastern Africa-Mesopotamia-Caucasus-Siberia path. A simple EAT index, which is based on 500hPa level average heights for the first weeks of March between 1979 and 2015, demonstrated statistically significant correlations with the surface temperatures over Europe and a region covering northeastern Africa and Middle East. Other indices related with EAT as well as an EOF analysis of EAT also support the finding that EAT plays an important role on the temperature distribution over a large area covering Europe, Northern Africa and the Middle East in the early spring.
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