Statistical prediction of winter rainfall in patagonia (Argentina)

This chapter describes rainfall evolution in southern Argentina (Patagonia) and faces with the possibility to predict winter rainfall using oceanic and atmospheric predictors. The Andes Mountain ranges along the west of Patagonia and a large plateau extends towards the east. A decrease of rainfall was observed in all seasons in central and east Patagonia meanwhile an increment is observed in southern part of Los Andes. The study area was regionalized using a principal component analysis and four regions could be defined. Almost all regions showed an annual cycle with maximum rainfall in autumnwinter. Therefore, several different statistical models: an autoregressive integrated moving average model (ARIMA), Holt Winter (HW), Climate Prediction Tool (CPT) and an ensemble of all, called multimodel were applied to predict MJJ (May to July) Patagonia rainfall in four regions defined in Patagonia. They were designed with MJJ rainfall for the period 1975-2007 in CPT model and for the period 1988-2007 in ARIMA and Holt Winter because this last two models use 1975-1987 values to generate the final scheme. All the models were proved for 2008-2012. The main result of this work is that the consideration of ARIMA and HW in the multimodel ensemble improves the efficiency obtained using CPT. This result was supported by the calculation of efficiency coefficients which represent the ability to detect over and sub normal rainfall. © 2014 by Nova Science Publishers, Inc. All rights reserved.