Influência do Tipo de Textura e Umidade Inicial do Solo Sobre a Simulação da Precipitação Sazonal e de Extremos de Precipitação no Sudeste do Brasil

N C R Ferreira,S C Chou

doi:10.11137/2018_3_680_689

Abstract

The objective of this paper is to investigate the influence of soil conditions (initial moisture and soil texture type) on the seasonal simulations of precipitation extremes over Upper Sao Francisco River basin in Brazil. The Eta regional climate model is used to produce simulations for the dry and rainy seasons in southeast Brazil between the years 1979 and 2012. These are 4.5-month integrations. Two maps of soil texture type and two initial soil moisture conditions are tested. Eta rainfall simulations are more sensitive to soil texture than to the changes in the initial soil moisture. The runs using the map of 26 soil texture types represent better the climate of South America compared to the simulations using the map of 9 soil texture types. In general, the extreme climatic indices and the total accumulated precipitation for the dry and rainy seasons in Brazil are underestimated by the Eta regional climate model over the study region, which suggests the necessity of tests with convection precipitation schemes to improve the model’s performance.

Highlights

The knowledge about climate is essential to help the management of activities, such as agriculture, water resources, energy supplies, and others socioeconomic sectors
We examine the effects of initial soil conditions and soil texture types in the simulations of seasonal precipitation extremes over the Upper São Francisco River basin in Brazil
We conclude that changes in the soil texture affected more the variation of simulated rainfall than the change in the initial soil moisture

Summary

Introduction

The knowledge about climate is essential to help the management of activities, such as agriculture, water resources, energy supplies, and others socioeconomic sectors. Climate models are valuable tools to support climate studies and extreme events such as droughts and floods, and the decision making in the various activities on economic sectors mentioned above. Regional Climate Models (RCM’s) use the technique so-called dynamical downscaling to detail the coarse horizontal resolution of global climate models. In the RCM, the reliability of the simulations at high resolution depends on the quality of the lateral boundary conditions, and on the ability of the regional model to develop realistic features of this climate (Chou et al, 2000; 2002). Studies have shown that regional models, in particular, the Eta model reproduces simulations of meteorological variables in seasonal and intra-seasonal ranges (Seluchi & Chou, 2001; Marengo et al, 2003; Cavalcanti et al, 2002)

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