Advances in Geosciences www.adv-geosci.net 1680-7340 1680-7359 16 Observation, Prediction and Verification of Precipitation (EGU Session 2007) 2008 10.5194/adgeo-16-55-2008 http://www.adv-geosci.net/16/55/2008/ http://www.adv-geosci.net/16/55/2008/adgeo-16-55-2008.html http://www.adv-geosci.net/16/55/2008/adgeo-16-55-2008.pdf 55 62 2008-04-09 Decadal changes in extreme daily precipitation in Greece P. T. Nastos nastos@geol.uoa.gr C. S. Zerefos Laboratory of Climatology and Atmospheric Environment, Faculty of Geology and Geoenvironment, National and Kapodistrian University of Athens, Greece National Observatory of Athens, Greece Academy of Athens, Greece The changes in daily precipitation totals in Greece, during the 45-year period (1957–2001) are examined. The precipitation datasets concern daily totals recorded at 21 surface meteorological stations of the Hellenic National Meteorological Service, which are uniformly distributed over the Greek region. First and foremost, the application of Factor Analysis resulted in grouping the meteorological stations with similar variation in time. The main sub groups represent the northern, southern, western, eastern and central regions of Greece with common precipitation characteristics. For representative stations of the extracted sub groups we estimated the trends and the time variability for the number of days (%) exceeding 30 mm (equal to the 95% percentile of daily precipitation for eastern and western regions and equal to the 97.5% percentile for the rest of the country) and 50 mm which is the threshold for very extreme and rare events. Furthermore, the scale and shape parameters of the well fitted gamma distribution to the daily precipitation data with respect to the whole examined period and to the 10-year sub periods reveal the changes in the intensity of the precipitation. 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