Las masas de aire que afectan el sur de la provincia de Santa Fe y su relación con la precipitación diaria en enero

the aim of this work is to identify the air masses that affect the south of santa fe in january during 1998-2006 and to relate it to the daily precipitation, in zavalla (33o01′s, 60o53′o). the analyzed daily information is: mean, maximum and minimum temperature, relative humidity, effective insolation, atmospheric pressure, precipitation and wind direction of the 8 and 14 hours. the fields of circulation and temperature in 1000 and 500 hpa, and specific humidity in 850 hpa, are calculated using ncep reanálisis data. analysis of cluster k-means is applied and it determines four types of air masses: warm drought: a very warm air mass; warm humid: it increases the humidity and cloudiness, moderate dry: air mass with the smallest minimum temperatures; moderate humid: very humid air mass, daily losses thermal amplitude, associated to the previous conditions to the passage of cold fronts. the 50% of the precipitation days happen during warm humid masses and the 32% with moderate humid, and 93% of the most intense occurs during these masses. moderate humid have major efficiency in the precipitation occurrence because in 50% of the cases precipitates, and for warm humid only in 27%.