Resumo

CORONEL, Alejandra S.  e  CASTANEDA, María E.. Classification of air masses that affect the south of Santa Fe, their trajectories and the relationship between them to the the daily precipitation in January abstract. Meteorologica [online]. 2010, vol.35, n.1, pp.29-40. ISSN 1850-468X.

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%.

Palavras-chave : Air masses; Backward trajectory; Daily rainfall; January.

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