Variabilidade Horária, Diária e Sazonal da Frequência e Intensidade de Precipitação em uma Floresta Tropical Chuvosa na Amazônia Brasileira (Hourly, Daily and Seasonal Frequency Variability and Precipitation Intensity in a Rainy Tropical Rainforest in the Brazilian Amazon)

A presente investigacao trata da analise de uma serie de indicadores de precipitacao e sua variabilidade temporal em uma area restrita de floresta da Amazonia Oriental. O objetivo principal foi analisar os padroes horarios, diarios, e mensais de precipitacao durante os periodos chuvosos e menos chuvosos da regiao. Foram utilizados as seguintes etapas: a) coleta de dados de precipitacao com pluviografos de bascula modelo TB4 conectado a um datalogger Campbell Scientific, modelo CR1000, instalado em uma torre micrometeorologica de 40 m de altura.; b) avaliacao de indicadores de precipitacao, que foi definido como o periodo diario no qual ocorreu no minimo um evento de precipitacao maior ou igual a 1,0 mm; c) testes estatisticos nao-parametricos para avaliar a hipotese de diferencas significativas entre os indicadores de precipitacao entre os periodos PC e PMC. Os resultados indicaram que tanto no PC como no PMC, a maior frequencia de chuvas incidiu na categoria de 1,0 mm.dia-1 a 10,0 mm.h-1. No PC as chuvas foram mais predominantes durante os turnos da tarde e noite e no PMC a predominância ocorreu, principalmente durante o turno da noite. O teste estatistico de Friedman (Fr(13,GL=11) = 55,73 e p < 0,0001) acusou, respectivamente, que a precipitacao do mes de marco foi a mais excentrica da serie no PC, enquanto que no PMC, foi a de agosto. Entao, confirma-se a hipotese de que, em florestas conservadas, durante o PC o regime de precipitacoes e estratificado, com chuvas prolongadas, enquanto no PMC as chuvas sao predominantemente convectivas. A B S T R A C T The present investigation deals with the analysis of a series of precipitation indicators and their temporal variability in a restricted area of the forest of the Eastern Amazon. The main objective was to analyze the daily, daily and monthly rainfall patterns during the rainy and less rainy periods of the region. The following steps were used: a) Rainfall data collection with TB4 model balloons connected to a Campbell Scientific datalogger, model CR1000, installed in a 40 m high micrometeorological tower; b) evaluation of precipitation indicators, which was defined as the daily period in which a precipitation event greater than or equal to 1.0 mm occurred at least; b) non-parametric statistical tests to evaluate the hypothesis of significant differences between precipitation indicators between PC and PMC periods. The results indicated that in the PC and PMC, the highest rainfall frequency was in the category of 1.0 mm.day -1 to 10.0 mm.h -1. In the PC, rainfall was more prevalent during the afternoon and evening shifts and in PMC the predominance occurred, especially during the night shift. Friedman's statistical test (Fr (13, GL = 11) = 55.73 and p <0.0001) accused, respectively, that the March precipitation was the most eccentric of the CP series, whereas in PMC, it was the one of August. Then, it is confirmed the hypothesis that, in conserved forests, during the CP the precipitation regime is stratified, with prolonged rains, whereas in the PMC the rains are predominantly convective Keywords: Precipitation Time Series, Seasonal Variability, Caxiuana National Forest