FUTURE CHANGES IN THE OCCURRENCE OF EXTREME PRECIPITATION EVENTS IN EASTERN MEDITERRANEAN

摘要

It is widely known that precipitation extreme events can generate great impact on human activities and natural environment. Therefore, the analysis of extreme precipitation events in the present and future climate is of great importance. For Eastern Mediterranean, recent studies have shown an increasing tendency of the dry spell length during the last two decades while appears one of the most sensitive areas regarding the future precipitation extreme conditions. Therefore, further work is required in order to understand the distribution and causes of precipitation extremes in Eastern Mediterranean and be able to get general conclusions about their future occurrence and impact. The aim of this study is to estimate future potential changes in duration of extreme dry and wet spells and rainfall intensity in Eastern Mediterranean. For this purpose, daily precipitation amounts, as derived from the regional climate model of the UK Hadley Centre HadRM3P have been used for the present period 1960-1990 (control run) and the future period 2070-2100. The data are available on 0.44°x 0.44° latitude by longitude grid through the European project MICE (Modelling Impacts of Climate Extremes). Future data are based on the B2a IPCC emission scenario. For the identification of the precipitation extremes three climatic indices were employed: a) CWD (Maximum number of consecutive wet days), b) CDD (Maximum number of consecutive dry days) and c) SDII (quotient of precipitation amount of wet days and the number of wet days of the specified period). The indices were calculated for the present and future period, on a seasonal and annual basis. The validation of model results (control run) against the station data for the present period demonstrated that the two datasets agree quite well. Then, our analysis has shown a general tendency towards longer dry spells in all seasons, except autumn. In addition, extreme wet spells are shortened in the future during all seasons, except autumn where their length is increasing at almost all sites. Similarly, precipitation intensity found reduced for all seasons. However, the uncertainties in the future response of climate and its variability still remain, implying that these results should be handled with caution and further work must be conducted.