Gilberto Chohaku Sediyama

Climatologia do comportamento do período chuvoso da região sudeste do Brasil

ABSTRACT: CLIMATOLOGY OF THE RAINY PERIOD BEHAVIOR IN THE SOUTHEAST REGION OF BRAZILDaily data from 203 pluviometric stations, located in the Southeast region of Brazil, were studied with the objective to characterize climatically and analyze the tendency of the behavior of the rainy period. The results indicate that the rainy period begins early (between 13 and September 22 th ) and has larger duration (210 to 229 days) at the coastal area of Sao Paulo. Behavior opposed to the observed in the areas North and Vale do Jequitinhonha, in Minas Gerais, where the rainy period begins on average, among October 23 th on November 2 nd , only lasting 136 to 155 days. The duration and the dates at the beginning of the rainy period are strongly correlated, as well as, among the precipitation total and the duration of the rainy period in practically the whole Southeast region of Brazil. In general, from middles of the 1970’s, the rainy period has started earlier and lasted more in the Southeast region of Brazil. In regard to the amount of rain, it has been occurred in larger amounts only in the MG3 (Southeast of Minas Gerais) area and in the State of Sao Paulo.

Regiões homogêneas e funções de distribuição de probabilidade da precipitação pluvial no Estado de Táchira, Venezuela

The objective of this work was to determine regions of monthly pluvial precipitation based on the seasonal and the probability distribution that best fit to precipitation of those areas in the State of Tachira, Venezuela. Long-term series of 24 throughout 62 years of monthly precipitation data of 25 climatological stations were used. The Wards clustering methods of analyses was used to group the months with similar monthly pluvial precipitation and also the climatological locations with similar precipitation (homogeneous regions). The adjust of the probability density functions exponential, Gamma, Gumbel, normal, log-normal were evaluated with three parameters as well as Weibull distributions in order to observe monthly precipitation data. The precipitation seasonal variation at the State of Tachira presents three periods statistically defined as: dry, transition, and wet. For the dry and wet periods, four homogeneous regions of locations with similar monthly precipitation could be identified and, in the transition period, three regions. In the dry period, the recommended probability distribution is the exponential, except for the homogeneous regions with the largest rainfall values during that period, when Gamma distribution is better. In the wet period, in all regions, normal distribution prevails, except for August, when Gamma prevails. As far as transition periods are concerned, Gamma distributions are better in April and normal distribution, in November.

Modelo de regressão para a previsão de produdividade de cafeeiros no Estado de Minas Gerais

The objective of this work was to set up and test a multiple linear regression model applied to principal components for representative coffee crop yield series for three places in Southern Minas Gerais, based on the model proposed by Stewart et al. (1976), with new variables, represented by agrometeorological elements, besides the soil water depletion for the four quarterly periods in agricultural cycle (July to June). Since the number of observations was lower than the amount number of variables, we resorted to principal component analysis to reduce the dimension of this set of variables. The multiple linear regression analysis was applied to the first three principal components. In agreement with the tests, the model presented relative errors of estimates with high discrepancies and a tendency to overestimate productivity for the three places. However, it was verified that the estimates for the model tended to present behavior similar to observed data.

Geotecnologias aplicadas à avaliação de parâmetros biofísicos do Pantanal

The objective of this work was to evaluate surface biophysical parameters of the Pantanal biome, Brazil, by the application of geotechnologies. The Sebal algorithm, Modis imagery, and land use and land cover map were used. The obtained results for NDVI, surface temperature, albedo, daily sensible heat flux, daily net radiation and daily actual evapotranspiration were consistent with literature data for the different land use and land cover classes, and corroborate the analytical and synoptic capacity of Sebal estimates. These results show the potential of geotechnologies in the implementation of models or algorithms developed for the understanding of biophysical process dynamics related to the soil‑plant‑atmosphere interactions in Pantanal.

Consumo de água em plantios de eucalipto: parte 1 determinação da condutância estomática em tratamentos irrigado e não-irrigado

In response to the growing interest in hydric need in eucalypt plantations and plant response as a function of environmental conditions, this work aimed to calculate water consumption in 2-year-old Eucalyptus grandis x Eucalyptus urophylla clones located both on irrigated and non-irrigated plantations. This work is divided into two parts. In the first, stomatal conductance is determined and the effect of seasonal variability of environmental variables is verified. In the second, stomatal resistance is modeled and eucalypt transpiration is calculated by the Penman-Monteith method. The experimental site was located in Belo Oriente, Minas Gerais, at 19o 1823 S latitude, 42o2246 W longitude and 220 m altitude. Stomatal conductance was measured in three different periods: humid period, early dry period, and dry period. Average values of stomatal conductance ranged from 0.41to 0.22mol m-2 s-1 for the irrigated treatment and from 0.38 to 0.24 mol m-2 s-1 for the non-irrigated treatment. Stomatal conductance was also found to decrease between the humid and dry periods. This variation was related with some environmental variables and soil moisture.

Eficiência do uso da água das culturas do milho e do feijão-caupi sob sistemas de plantio exclusivo e consorciado no semiárido brasileiro

This study aimed to analyze the productivity, the water use efficiency, and the economical viability for corn and cowpea crops on single and intercropping systems in the Brazilian semiarid region. The experiment was carried out at Petrolina, State of Pernambuco. The crops, in different planting systems (single and intercropping), underwent the five blades of irrigation, ap - plied at the flowering stage of cowpea to 40 days after sowing. Combining the settings of cultivation system and the differ - ent depths of irrigation, crops of maize and cowpea were subjected to 15 different treatments. To evaluate the performance of crops in the different treatments indicators that consider the production response of crops and the performance of the application of water in the production system were used. The grain yield responses of maize and cowpea to the soil water content were reduced in intercropped plantations, in relation to single cropping. Even so, in economic terms, the adoption of maize-cowpea proved to be more advantageous in all treatments.

Oscilações climáticas em Minas Gerais

O coeficiente angular da analise de regressao e o coeficiente de Mann-Kendall foram utilizados para analisar tendencias climaticas mensais da temperatura maxima, da temperatura minima, da insolacao e do conteudo de vapor dagua, em algumas localidades do Estado de Minas Gerais. Ambos os testes estatisticos foram aplicados para tres diferentes periodos, sendo um de 1961 a 2004, e os demais, em intervalos divididos pelo ponto de descontinuidade identificado pelo Teste de Homogeneidade Normal Padrao (THNP). Os resultados mais relevantes indicam que, em Minas Gerais, a temperatura maxima e a temperatura minima cresceram no periodo 1960-2004, entre 1,3oC e 3,9oC, mas este comportamento nao foi geralmente gradual, sendo associado com a descontinuidade que ocorreu principalmente na decada de 1990. A maior parte do crescimento significativo da temperatura maxima centrou-se entre setembro e dezembro. O predominio de tendencia positiva para o vapor dagua e coerente com o aumento observado dos extremos da temperatura. Entre as poucas tendencias significativas da insolacao, a predominante foi de decrescimo da decada de 1960 ate meados da decada de 1990.

Consumo de água em plantios de eucalipto: parte 2 modelagem da resistência estomática e estimativa da transpiração em tratamentos irrigados e não-irrigados

This paper concludes the last part of the work aimed to calculate water consumption in eucalypt plantations. Stomatal resistance was modeled as a function of the following ambient variables: global solar irradiance, vapor pressure deficit and temperature. Based on stomatal resistance modeled from the values observed in the first part of this work, eucalypt transpiration by the Penman-Monteith method could be calculated in some days during the humid and dry periods of the year. Correlation between stomatal resistance and ambient variables was verified. The models generated by this relation proved efficient in calculating the diurnal variation of stomatal resistance as well as hourly and daily transpiration totals.

Guidelines for irrigation scheduling of banana crop in São Francisco Valley, Brazil . II - Water consumption, crop coefficient, and physiologycal behavior

The water consumption and the crop coefficient of the banana cv. Pacovan were estimated in Petrolina County, northeastern Brazil, in order to establish guidelines to irrigation water management. Evaluations were carried out since planting in January 1999 to the 3rd harvest in September 2001 on a microsprinkler irrigated orchard, with plants spaced in a 3 x 3 m grid. Average daily water consumption was 3.9, 4.0, and 3.3 mm in the 1st, 2nd and 3rd growing seasons, respectively. Crop coefficient values increased from 0.7 (vegetative growth) to 1.1 (flowering). Even with high soil water availability, transpiration was reduced due to high evaporative demand.

Comparação de produtos de precipitação para a América do Sul

COMPARISON OF PRECIPITATION PRODUCTS FOR SOUTH AMERICA This work compares five precipitation datasets for South America, for the period 2000-2004, considering the meridional variation, the variation across the main continental watersheds (Amazonas, Tocantins, Sao Francisco, Orinoco, Parana/Prata, in addition to the main Patagonia basins) and across the main vegetation types (tropical evergreen forest, tropical deciduous forest, woodland, savanna and grassland/steppe). We compare three products based on a combination of rain gauge measurements and satellite data (TRMM, CMAP and GPCP) and two based on reanalyzed meteorological datasets (NCEP/NCAR and CPTEC). The results indicate that the annual average precipitation fields of the different products present different behavior among them. For example, the CPTEC reanalysis does not represent the main regimes of precipitation in the continent, overestimating the precipitation in the interior of northeast Brazil and underestimating the precipitation in the rest of the continent. The combined rain gauge-remote sensing products obtained similar patterns, mainly CMAP and GPCP.