Sequeres i circulació atmosfèrica a la Mediterrània Occidental

Abstract

This thesis examines the phenomenon of drought in the western Mediterranean weather (Balearic islands), understood as those periods in which there is a decrease in rainfall compared to the average area over a certain period of time between 1950 and 2010 in this case. Droughts are a risk geographical area that historically have affected the Balearic year given the irregularity of rainfall typical of the Mediterranean climate. For this reason we have selected a total of 62 stations located in the Balearic Islands. 3 on the island of Menorca, Mallorca 53, 4 to Ibiza and Formentera 2 according to the criteria of availability of monthly and daily rainfall data from the sixty years of the study period and made to ensure a minimum coverage of the entire archipelago. To detect dry years has been used in the first quintile while the classic method to detect those episodes where the rainfall deficit extends beyond 12 months standardized drought index that rainfall in the context of similar studies Spanish Levant with climatic conditions similar to the Balearic Islands have proved to be fully efficient. Once detected major droughts that have affected the island territory (1950-2010) have been mapped using a geographic information system abnormalities compared to average values observed up to seven annual rainfall distribution patterns of droughts Islands. In this sense there is a mixed affect both temporal and spatial drought in the Balearic Islands. For which reason also mapped the geographic and temporal evolution of these episodes using the results of the índexestandarditzatanteriorment said. Finally has tried to find a possible correlation between the appearance of these cyclical droughts with the atmospheric circulation in the western Mediterranean. Firstly these droughts has been linked with both daily and monthly data with synoptic classification of Jenkinson and type of time while Collinson was subsequently correlated with three teleconnection patterns that, according to previous studies may influenced more or less with actual rainfall are the Southern Oscillation, the North Atlantic Oscillation and of the Western Mediterranean. Correlations have been observed both real and questionable regarding these patterns and monthly totals of precipitation.