Sur la variabilite des precipitations dans la basse Californie du nord (Mexique)

Abstract

Mean monthly data values of 36 climatological stations, for the period 1957 to 1983, have been used to study the tropical influence on the point rainfall observations over Northern Baja California Peninsule. The results show the time and space variability of the precipitation field associated to a tropical origin. During winter, the precipitation field is mainly of middle-latitude (i.e. north Pacific ocean) origin. During summer, the precipitation has a tropical origin (i.e. tropical eastern Pacific and tropical Atlantic oceans); however, lhe amount of precipitation is strongly dependent on planetary-scale phenomena, cvidencing considerable summer tropical influence du ring NON-ENSO events (El Nifio/Southern Oscillation). The tropical Index, (defined by the ratio between the sum of the medians of monthly precipitation during the summer over the sum of the medians of monthly precipitation during the year) is maximum during 1963, 1967, 1971 and 1976, with magnitudes of 42%,48%, 59% and 57%, respectively. The four of them coincide with positive anomalies of the Southern Oscillation Index.