Searching for correlations between large-scale climate indices and meteorological drought in Greece

This diploma thesis aims to investigate the possibility of forecasting the meteorological drought and conditions of dryness in general, in Greece. Also, an attempt to investigate the presence of some specific conditions in the atmosphere that lead to correlations, in terms of climate, between areas that are located far away from each other, is made. The most representative climatic indices are the NAO and the ENSO34 index. The first one expresses the difference of sea level pressure between the tropical high in Azores and the polar low in Iceland. The second represents the sea surface temperature anomaly in a place located in the tropical Equatorial Pacific with geographical coordinates 5°Ν-5°S, 170°E-120°W. In order to achieve the objective of the research, precipitation data of seven distinct Greek cities with divergent precipitation conditions were examined. The determination of potential correlations between the extremely low values of precipitation in various time scales (monthly, seasonally, yearly) and the average values of the used indices in preceding time periods (month, season) was approached through correlation coefficients between the given time series and extended analysis through graphical material. Despite the thorough examination, only tenuous correlations were reached. This fact strengthens the view, that the global climatic system is remarkably too complicated to be described only by simplified climatic indices and that the impact of these phenomena on the climate of Greece is indirect and weak.