Influência de algumas forçantes climáticas no período chuvoso da Região Sudeste do Brasil e suas conseqüências para as culturas da soja e do milho

• Autor(a) principal: Minuzzi, Rosandro Boligon
• Data de Publicação: 2006
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1508
• topic: Precipitação; El Niña; La Niña; Dipolo do Atlântico; Soja; Milho; Precipitation; El Niño; La Niña; Atlantic dipole; Soybean; Corn; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::AGROMETEOROLOGIA

Daily data from pluviometric and meteorological stations were used to analyze statistically the influence of the climate forcings El Niño-southern oscillation (ENOS) and tropical Atlantic dipole on the rainfall behavior at different temporal scales during the rainy period (PC) in Southeastern Brazil (SEB). The influence of ENOS on the different phenological stages and planting times (October 1st and November 1st) of medium-cycle crops (120 days duration) corn and soybean, in SEB s arable lands, was also analyzed. The classifications of the beginning (IPC) and end (FPC) of rainy periods and total amount of rainfall were based on average, maximum and minimum values, respectively, using the quantis technique and the normalized deviations. Besides the classification, monthly and quarterly rainfall amounts in years of occurrence of climate forcings were correlated with the Southern Oscillation Index (IOS) and the sea surface temperature (TSM) of equatorial Pacific regions and North and South Tropical Atlantic Basins, using total and partial lag correlations, lagging up to nine months. In SEB areas that had at least two significant lag correlations at 95% of probability between the monthly and/or quarterly rainfall and the regions of Equatorial Pacific and Tropical Atlantic oceans, the confidence interval was determined for the average number of rainy days, which were divided into four intensity classes. On the basis of two areas correlated with each other and located in the far north and far south of SEB (MG1 and SP3), Principal Components Analysis and Multiple and Total Linear Regression were used to analyze four situations of simultaneous occurrences of climate forcings. The Effective Drought Index and the Water Requirement Satisfaction (only for Minas Gerais), in soils with three different water retention capacities (30 mm, 50 mm and 70 mm) were chosen to evaluate the climate risk on soybean and corn during ENOS occurrences. The positive phase of the Atlantic Dipole was shown to be the most evident climate forcing at the beginning of the rainy period, whereas at the FPC, the most significant results were found in Negative Dipole years of the Atlantic, tending to end late in the MG1, ES1, SP3 and SP4 regions, with reverse behavior in the RJ1 region. The expressive anomalies of monthly and quarterly rainfalls, observed in years of LN climate forcing, were barely related with equatorial Pacific TSM, while El Niño had less influence on the beginning and end of rainy periods and on the monthly and quarterly rains of Southeastern Brazil. The influences on the soybean crop are more visible during La Niña occurrences, in which the municipal districts Patos de Minas , Lavras and Sete Lagoas were reached, mainly plantings carried out on October 1st. In El Niño years, the regions of Lavras and Sete Lagoas are more susceptible to drought effects, resulting from the climate forcing, mainly soybean plantings carried out on November 1st. With respect to the corn crop, the middle-south region of Minas Gerais is more susceptible to La Niña effects, regardless of the planting time and soil type. In El Niño years, however, the regions of Lavras and Sete Lagoas are more affected, mainly plantings carried out on October 1st, during the vegetative and maturation stages and soils with available water capacity (CAD) of 30 mm in both regions and CAD of 50 mm in the Lavras region.