EL-NINO SOUTHERN OSCILLATION AND NORTH-ATLANTIC OSCILLATION CONTROL OF CLIMATE IN PUERTO-RICO

Many studies have shown that the El Nino-Southern Oscillation (ENSO) h as a significant influence on climate in many parts of the globe, most ly in the Pacific Basin. The objective of this study is to examine the possible impact of ENSO on climatic patterns on the island of Puerto Rico in the Caribbean. The authors find that annual mean air temperatu res are controlled by ENSO since 1914. El Nino years are associated wi th warm air temperatures, whereas El Viejo (La Nina) years, which are the opposite of El Nino, are cooler. On the other hand, since 1911 flu ctuations in annual rainfall amounts are synchronous with variations i n the North Atlantic Oscillation (NAO) during the winter and are not c ontrolled by ENSO. During years of a high winter NAO index, when the a xis of moisture transport in the North Atlantic changes to a more sout hwesterly-northeasterly orientation, annual precipitation in Puerto Ri co is lower than average.