In this work, a synoptic classification of sequence patterns of sea level pressure (SLP) and 500 hPa geopotencial heights associated with cold waves over São Paulo city was carried out. The rotated "Principal Components Analysis" (PCA) is used to obtain the basic patterns of sequence of SLP and 500 hPa geopotential heights. The results show three dominant types of patterns of circulation associated with cold waves in São Paulo city during 1960-2002 period, which explain 70% of the total variance. The dominant pattern represents the incursion of an intense postfrontal anticyclones in low level, close to 80°W, 45°S, and a ridge over the Pacific ocean at upper level, producing cold air advection over central and southern Brazil. The second pattern is associated with occurrence of cyclogenesis forming in the Atlantic ocean, next to the southern Region of Brazil, with a blocking aloft configuration. Finally, it is observed a pattern related with the passage of a cold fronts with a zonally trajectory, due to the presence of a pronounced trough extending southward over the south of the continent.
synoptic classification; cold wave; principal components
