Avaluació de les connexions entre l'índex NAO d'hivern i les precipitacions hivernals al Pirineu Andorrà

(CAT) En aquest estudi s'ha correlacionat l'índex de l'Oscil·lació de l'Atlàntic Nord (NAO) Lisboa- Stykkisholmur/Reykjavik corresponent a l'hivern amb les precipitacions del uadrimestre desembre - gener- febrer- març de dos observatoris del Pirineu andorrà, Escaldes i Ransol, durant el període 1935-2000.Els resultats obtinguts permeten cobrir en part les mancances de dades en un espai com el pirinenc i establir connexions amb altres sectors de la península Ibèrica. (ENG) In this research, a correlation has been made between the North Atlantic Oscilation (NAO) index Lisbon-Stykkisholmur/ Reykjavik corresponding to the winter rainfalls of the December - January - February - March quarter from two observatories in the Andorran Pyrenees, Escaldes and Ransol, between 1935 - 2000. The results obtained partly make up for the lack of data in an area such as the Pyrenees and allow connections to be made with other areas of the Iberian Peninsula. The North Atlantic Oscillation index consists in linking surface pressure values from an area in the subtropical Atlantic with the surface pressure values in an area of the subpolar Atlantic. If the difference between the subtropical Atlantic pressure and the subpolar Atlantic pressure is positive, it is referred to as positive NAO index. If the difference is negative, it is negative NAO index. The NAO allows an estimation to be made of the intensity and path of westerly currents on temperate Europe. Also, due to the ease with which the dominating position of the main centres of action change in the north Atlantic in contiguous years or seasons, the NAO index is a very useful tool with which to evaluate meteorological anomalies and the variability of the climate in western Europe. The following study aims to correlate winter rainfalls in the Pyreneen sector of Andorra (the south facing stretch of the central-easterly Pyrenees) with the winter NAO index (from December to March) and thus extract conclusions which will better contribute to regionalisation.