Kapitel: 3.1.8 Die Niederschlagsentwicklung im mediterranen Raum und ihre Ursachen

Mediterranean rainfall changes and their causes:

Based on a revised version of the CRU (Norwich) gridded monthly rainfall data, trends in Mediterranean precipitation for the 1951–2000 period are calculated on a seasonal scale.

The most important characteristic is the widespread rainfall decrease during the winter half-year which is linked to particular changes in atmospheric circulation patterns identified by canonical correlation analyses: a shift to preferred positive modes of the NAO-linked Mediterranean Oscillation since the 1980s, a weakening of the central Mediterranean trough since the late 1980s, and a modal change since the 1970s implying increased pressure in the Mediterranean area.

Statistical downscaling assessments for enhanced greenhouse conditions at the end of the 21st century indicate some further developments: rainfall increases in high winter and decreases in spring and autumn for western and northern Mediterranean regions, but mainly negative changes throughout the rainy period for southern and eastern regions.