Possible influences of pacific decadal oscillation in the ten day based radio between actual and potential evapotranspiration in the region of Campinas, São Paulo State, Brazil

Abstract

Considering the importance of the ratio between the actual and potential evapotranspiration (AE/PE) for agricultural purposes, the present study estimated the 10-day based AE/PE, aiming to evaluate possible influences of the Pacific Decadal Oscillation (PDO), on temporal variability series, in the region of Campinas, São Paulo State, Brazil. The shapes of the beta probability density function of the AE/PE series for four periods (two in the cold PDO phase and two in the warm PDO phase) do not show differences between the PDO phases. In this sense, the use of "average periods" to obtain a standard climatology for agrometeorological purposes (such as the climate normal of the 1961-1990 period, which encompasses sixteen years of the cold PDO phase and fourteen years of the warm PDO phase) should not result in significant errors in the region of Campinas, SP. However, considering academic/scientific purposes, the analyses of the autocorrelation functions of the residual AE/PE series for the four periods show differences in the persistence between the two phases of the PDO. Tendo em vista a importância agrícola da razão entre a evapotranspiração real e potencial (ETR/ETP), estimou-se esta relação (em escala decendial), a fim de verificar possíveis influências da Oscilação Decadal do Pacífico (PDO) sobre a variabilidade temporal desse parâmetro agrometeorológico na região de Campinas, Estado de São Paulo, Brasil. Pelas formas da função de densidade de probabilidade Beta das séries de ETR/ETP para quatro períodos (dois na fase fria, e dois na fase quente) não se observam diferenças significativas (influência) entre as fases da PDO. Nesse aspecto, sob o ponto de vista agrometeorológico, o uso de um determinado "período médio" (tal como a normal climatológica de 1961-1990, que compreende dezesseis anos da fase fria e catorze da fase quente), para caracterização de séries temporais de ETR/ETP, não deve resultar em grandes erros. No entanto, sob o enfoque científico/acadêmico, diferentes "graus de persistência" das séries de anomalias de ETR/ ETP foram observados nas duas fases da PDO. Nas fases frias, foram detectados maiores graus de persistência; sugere-se, assim, que a variabilidade temporal da ETR/ETP na região de Campinas pode estar relacionada à variabilidade de longo prazo da temperatura da superfície dos oceanos tropicais.Palavras-chave: normal climatológica, temperatura da superfície do mar.

Probable reference evapotranspiration for Chapecó, Santa Catarina, Brazil

“…The mean error ranged from 0.0145 to 0.0535 with a mean of 0.0309, showing that the probability estimates of evapotranspiration events with the Beta distribution have a mean error of less than 6%. These results agree with other studies showing that the Beta distribution is suitable for analyzing the frequency of evapotranspiration data (BLAIN et al, 2009).…”

Soybean and maize off-season sowing dates when cultivated in succession: impacts of climate variability on yield and profitability

“…The complex interaction of rainfall, solar radiation, air temperature, and other meteorological parameters with plant and soil characteristics make challenging the determination of the best sowing date for soybean-maize succession in the different Brazilian producing regions, mainly when the effects of El Niño Southern Oscillation (ENSO), Pacific Decal Oscillation (PDO), and other phenomena are considered (BLAIN et al, 2009;DA ROCHA et al, 2014;ERASMI et al, 2014). The ENSO phenomenon alters the rainfall regime, causing serious problems for In order to test our hypothesis, three calibrated and validated soybean and maize crop simulation models were used to simulate soybean-maize succession yields in Brazil, aiming to determine the influence of ENSO phases on the spatial and temporal yield variability of soybean-maize succession and, therefore, to determine the best sowing window for soybean-maize off-season succession in different producing regions and for each phase of this phenomenon.…”