Variabilidade regional das nuvens de chuva na Bacia Amazônica visto por uma rede de radares meteorológicos

Abstract

A new dataset based on 5 years of operational meteorological weather radars from Amazon Protection System has enabled new knowledge in relation to rainfall in the Amazon Basin. The dataset has been calibrated against the TRMM-PR to remove bias and filtered to remove partial bean blocking by topography. Peculiar characteristics of 10 different regions are discussed from the point of view of the annual and diurnal cycles of reflectivity, as well as the vertical distribution of precipitation. Rainfall variability are analyzed on west and northwest Amazon and under different regime meridional wind. Lightning data are used to supplement the analysis of raincloud features. Similarities between the annual and diurnal cycles are found in northwestern and western, southwestern and southern, and northeastern and northern Amazon. Nocturnal peaks are found in stratiform fraction on southern, southwestern, western, northwestern, northern, central western, and coastal region. The convective fraction on western, northwestern, northern and central eastern region also show nocturnal peaks. Analysis of the vertical distributions of radar reflectivity at each radar site indicates that in the northern coast close to Belém heavy rainfall with deep convective systems is observed throughout the year. More oceanic-like clouds are also observed there and in other locations in the northern coast like Macapá, where the frequency of lightning is quite low. The locations in western Amazon, São Gabriel da Cachoeira and Tabatinga are closer to the Andes Mountains which may influence the rainclouds. São Gabriel da Cachoeira located in the northwest portion of the Amazon Basin has a regime with rainfall in all seasons with a slight decrease from August to October when the systems become more convective and with more lightning. The rainfall variability on northwest and western Amazon show that in northern wind regimes, the rain are more frequent in both São Gabriel da Cachoeira as Tabatinga, however they tend to be more intense and more convective under south wind in São Gabriel da Cachoeira and north wind in Tabatinga.