| The goal of this dissertation is to clarify the connection between the regional scale of Caribbean rainfall variability and the large scale of the surrounding climate patterns: the El Niño-Southern Oscillation (ENSO) and the North Atlantic Oscillation (NAO). The mechanisms by which anomalies in Caribbean climate arise are discussed: (1) the ENSO teleconnection to the Atlantic Ocean in its atmospheric and oceanic components, with the influence of the atmospheric bridge on the surface pressure gradients, winds and sea surface temperatures; (2) the impact of the NAO on tropical Atlantic SST variability, whereby changes in wind speed affect the magnitude and direction of surface heat fluxes.; A warm ENSO event is associated with drier than average conditions in the Caribbean during the months leading to the mature ENSO phase, the effect of a locally divergent atmospheric circulation, and with a reversal to wetter than average conditions during the months following mature conditions, the effect of ENSO's forcing of SST anomalies in the tropical Atlantic. A positive NAO implies stronger than average northeasterly trade winds and a cooling of the tropical North Atlantic by way of increased evaporation, hence less rainfall downstream, in the Caribbean basin. (The signs of the rainfall anomalies reverse for ENSO and NAO patterns of opposite sign.); Knowledge of the state of Atlantic and Pacific climate, e.g. whether an ENSO event is developing or decaying, and what the state of the NAO was during the previous winter, should provide a simplified prediction scheme to be used as verification for regional prediction efforts to be developed. |
