Climatologia de frentes frias no litoral de Santa Catarina

Abstract

A climatology of cold fronts at the coast of State do Santa Catarina, Brazil, is established based on 10-year period (1990-1999) of NCEP-NCAR reanalysis data. The cold front passages were objectively identified taking into account the wind shifts to a southerly direction, as well as the persistence of southerly wind for at least one day, and a decreasing of air temperature. The results show that, on the average, 3 to 4 cold fronts reach coast of Santa Catarina, each month, with an interval of 8 days. The composite data analysis, using the date of days of cold front passages at Santa Catarina as reference, shows clearly a climatological pattern of evolution, with cold front moving typically from southwest to northeast. In terms of seasonal mean, during winter, one day before reaching coast of Santa Catarina (day -1) the cold front is observed at Rio Grande do Sul. After passing at Santa Catarina (day 0), it continues to move equatorward, reaching the coast of Rio de Janeiro one day later (day +1), until it reaches latitudes close to 20°S (day +2), in the its stage of dissipation. In the third day, after the passage at Santa Catarina, the cold front is no more observed. Similar pattern of evolution is observed during summer, though the cold fronts are less intense and of slightly more rapid dissipation. © 2004 Sociedade Brasileira de Geofísica.