Ajuste de un modelo VARMA para los campos de anomalías de precipitación en Centroamérica y los índices de los océanos Pacifico y Atlántico Tropical

ERICK J. ALFARO, LUIS CID

Abstract

Several studies had shown that the anomalies of the sea surface temperature of the Tropical Atlantic and Pacific Oceans, are related to variations in the duration and timing of the rainy season in Central America. Cluster analysis was used to identify common patterns of 72 rain gauge stations of the region, with their anomaly time series as grouping variables, five clusters where identified through this process. A Vector Auto Regressive-Moving Average (VARMA) model was fitted to the data to quantify the ocean-atmosphere interaction between the oceanic indices of the Tropical North and South Atlantic, the Tropical Eastern Pacific and the first EOF's of the regional rainfall clusters. This model shows that the Tropical North Atlantica has the largest influence over the region when compared with the influence of the other indices, having positive correlation with the rainfall EOF’s. The Niño 3, instead, was found to have lower correlation with the rainfall of the region, influencing only the Pacific related clusters. This work shows that the variability of Tropical North Atlantic sea surface temperature anomaly (SSTA) presents stronger associations with the Central America rainfall, than the Tropical Eastern Pacific SSTA. The Tropical North Atlantic SSTA is maynly related to the degree of development of the Tropical Upper Tropospheric Through (TUTT) and SSTA of the Niño 3 region with meridian position of the Intertropical Convergence Zone (ITCZ).

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