Teor e transporte de vapor d'água na atmosfera do Nordeste do Brasil.

Abstract

In this study the spatial distribution and inter-annual variation of precipitable water, atmospheric water vapour transport and water budget over northeast Brazil (NEB) are investigated. The study is confined to the months March, April and May which represent the rainiest period of the year for the northern and eastern parts of the region. The inter-annual variations of the atmospheric parameters is analysed by comparing conditions during 1977 (normal), 1983 (dry) and 1986 (wet) years. The Regional Atmospheric Modeling System (RAMS), was used for the simulation of fields of precipitable water and water vapour flux. Soil and vegetation data is included in the model and the climatic mean sea surface temperature is used as the boundary over the ocean. To initialize the RAMS, data from the National Center for Atmospheric Research/National Center for Environmental Prediction (NCAR/NCEP) reanalysis is used. The results reveal fluctuations in precipitable water content due to orographic effects and characteristics of the ocean-continent interface. The vertically integrated water vapour flux indicates a relation between the meridional component and rains in northern part of region. In 1986 (wet year) the water vapour influx was 1.7 mm/day while during 1983 (dry year) the out-flux was 1.8 mm/day. Rainfall rates derived from precipitable water content variation agreed well with observed rainfall data. Results of the study suggest that the RAMS model can provide a reliable tool for the study of atmospheric water vapour content and transport over NEB.