E. Xoplaki et al., Connection between the large-scale 500 hPa geopotential height fields and precipitation over Greece during wintertime, CLIMATE RES, 14(2), 2000, pp. 129-146
The spatial distribution of the winter (December to February) precipitation
over Greece was related to the eastern North Atlantic-European scale mid-t
ropospheric circulation fields by means of empirical orthogonal functions (
EOFs) and canonical correlation analysis (CCA). The data used in this study
are winter precipitation totals, of 23 stations, equally distributed over
Greece, and winter mean 500 hPa geopotential heights (30 to 70 degrees N, 3
0 degrees W to 50 degrees E) for the period 1958 to 1994. The Greek precipi
tation data were found to be homogeneous (Alexandersson test). A decrease o
f winter precipitation over the whole country was found, although significa
nt (Mann-Kendall trend test) only over the northern and eastern parts and i
n the western mountainous regions. Three CCA patterns represent links that
are very reasonable from a physical point of view. It is supposed that stro
nger westerlies over the eastern North Atlantic and the raising of the 500
hPa geopotential height (and also the sea level pressure) over continental
Europe during the last few decades were connected with enhanced atmospheric
stabilization and anomalous advection of cold and dry air from northerly d
irections. This led to the winter dryness over the eastern Mediterranean. T
he probable mechanisms and processes in the complex atmosphere-ocean system
, leading to the regional anomalous climatic conditions, are discussed.