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Revista Brasileira de Meteorologia

Print version ISSN 0102-7786

Abstract

TAVARES, João Paulo Nardin  and  MOTA, Maria Aurora Santos da. Thermodynamic conditions of extreme rainfall events in Belém-PA, Brazil, during the rainy season. Rev. bras. meteorol. [online]. 2012, vol.27, n.2, pp. 207-218. ISSN 0102-7786.  http://dx.doi.org/10.1590/S0102-77862012000200007.

The thermodynamic conditions from any region are very important to the development of the deep, moist convection, mainly in the tropical region. Therefore, the aim of this work was to understand and characterize the role of atmospheric thermodynamic conditions during extreme rainfall events in the rainy season, in Belém (PA, Brazil). The results show that the extreme rainfall, in their majority (56%) present a pre-storm environment with strong instability, indicated by the CAPE high values (above 1000 J/kg) and meaningful values of the instability indexes. There was, however, events with low values of CAPE in the 1200 UTC sounding at the day of the event, but larger values in the day before, which indicates that the rain in question may have begun in the early hours and have last for several hours, crossing the time of the sounding, explaining the decrease of this parameter. The K, TT and LI instability indexes showed a close representation of the environment, predicting storms with heavy rainfall with 74% of correct identification, if taken into account the events on which all indexes showed the same indication of strong instability. Therefore, thermodynamic conditions of strong instability may lead to storms, but are not the only responsible factors for convective storms with extreme rainfall.

Keywords : CAPE; Instability indexes; Severe Weather; Extreme precipitation.

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