Análise temporal da atuação das frentes frias em Cuiabá-MT : 1996-2015

Abstract

In the present study was carried an analysis of the performance of the cold fronts in Cuiabá - MT in the period 1996-2015. In this research we observed the behavior of the climatic elements that characterize the performance of a cold front, such as temperature, relative air humidity, wind direction and rainfall. It was also elaborated a categorization of these cold fronts regarding the intensity, using as main parameter the air temperature. For the achievement of this research were obtained meteorological data on surface next to CPTEC and INMET, analysis of the bulletin of the Climanálise magazine and images of satellite GOES in the infrared channel. Were identified a total of 333 cold fronts, of which 230 they concentrated in the months of May to September of the time series studied. This period corresponds to the beginning and end of the dry season in the region, representing 69% of the total cold fronts. The years 2003 and 2007 presented the highest action of cold fronts, in a total of 23 for each year. In 2001 and 2002, there were smaller shares of cold fronts, with 9 and 10, respectively. The annual average for the historic series was on 16.5 cold fronts. The highest frequency of quantity occurred in the range of 16 to 20 cold fronts per year. The duration of the cold front in Cuiabá had a higher frequency between two and four days. The lowest temperature recorded was 278.6 K in July / 2013 and the lowest maximum daily was 285.3 K in July / 2010. The maximum thermal amplitude for a period of 24 hours occurred in July / 2013 with a variation of 293.6 K, in which the temperature declined from 309 k to 288.4 k. The categorization of these frontal systems indicated the performance of 237 cold fronts of weak intensity, representing 71.2% of the total. We also identified 88 fronts of moderate intensity (26.4%) and only 8 of strong intensity (2.4%). The study showed that the passage of cold fronts in Cuiabá and region changes considerably the patterns of the climatological variables of a place with typical tropical climate. It also made possible the elaboration of a proposal for the categorization of cold fronts, as well allowed a better understanding about the performance of frontal systems from southern South America to tropical areas of the interior of the continent. In Mato Grosso, due to the lack of works in this field, the present study becomes a contribution to research related to regional atmospheric circulation.