Brazilian biomes are home to a significant portion of the world’s biodiversity, with a total of 14% of existing species and still concentrate 20% of the world’s water resources. However, changes in biomes have a direct impact on rainfall patterns and water recycling. Based on this, the objective was to evaluate the variability of rainfall in the four existing biomes in the Northeast Brazil (NEB) and their interaction with the ENSO climate variability mode and regional scale meteorological systems via CHELSA product. For this, monthly rainfall data were used from 1979 to 2013, with a spatial resolution of 1 km × 1 km of the CHELSA product, and seasonal and annual rainfall patterns were extracted via boxplot. It was found that the rainy season in the Amazon, Caatinga and Cerrado biomes occurred between January and April, with varying intensities, except for the Atlantic Forest. Such seasonality patterns are associated with the NEB meteorological systems, with emphasis on ITCZ (all Biomes), UTCV (Amazon, Caatinga and Cerrado), Frontal Systems (extreme south of Caatinga, Cerrado and Atlantic Forest) and EWD/TWD in the (Atlantic Forest). In the inter-annual scale, the remarkable influence of ENSO was verified, mainly in the years 1983, 1985, 1989, 1993, 1998, 2009 and 2012. It is noteworthy that 1985 was the wettest year of the period, with a surplus in all biomes, while the driest year differs between the Amazon (1983), Atlantic Forest and Caatinga (1993) and Cerrado (2012) biomes. The study via orbital product in NEB showed that anthropogenic processes and natural variability interfere with the forms of rain interception in the biomes and hence in rainfall patterns and water recycling in NEB.

The objectives of this study are to use a clustering technique to identify homogeneous rainfall regions in the watersheds of the eastern region of the state of Paraná and to associate the spatial and temporal distribution of rainfall with the influences of orography, the ocean and regional atmospheric dynamics. Rainfall data were obtained from 54 pluviometric stations and from eight meteorological stations, which comprise the historical series from 1976 to 2015. A cluster analysis technique was used with the Euclidean distance for measuring proximity and Ward’s method for hierarchical grouping. The Litorânea watershed exhibited the highest rainfall totals in the study area, and the annual average was 2551 mm for the homogeneous group with the highest rainfall. The Ribeira river watershed exhibited the lowest total rainfall (1488 mm); therefore, it was considered a rain shadow region with a more tropical climate due to the concentration of rainfall in the period from September to March. The Alto Iguaçu watershed was characterized by the smallest spatiotemporal variation in rainfall due to its flatter relief and the influence of the subtropical climate.

O objetivo deste artigo é caracterizar a variabilidade espaço-temporal e interanual da chuva no Estado do Rio de Janeiro (ERJ) entre 1979 e 2009. Para isso foram utilizados dados de chuva de 99 estações pluviométricas, meteorológicas convencionais e automáticas distribuídas nas oito regiões de Governo do ERJ. As regiões de Governo com os maiores percentuais médios de falhas registradas foram Metropolitana, Costa Verde, Baixadas Litorâneas, Centro Sul, Médio Paraíba, Norte, Serrana e Noroeste. As falhas identificadas foram preenchidas com dados do produto 3B43 do satélite TRMM e com as normais climatológicas do INMET. A chuva média anual do período de estudo obtida para o estado foi de 1544 mm. As regiões Baixadas Litorâneas (2144 mm), Costa Verde (1912 mm), Médio Paraíba (1602 mm), Metropolitana (1571 mm) e Serrana (1547 mm) registraram média maior que a média estadual do período, enquanto as regiões Centro Sul (1307 mm), Noroeste (1235 mm) e Norte (1033 mm) ficaram abaixo da média. Todas as regiões registraram meses menos chuvosos em junho, julho e agosto. Já os meses com maiores totais de chuva foram registrados entre novembro e março, dependendo da região. A alta influência do relevo (altitude) no regime de chuva em todo o ERJ ficou caracterizada, principalmente nas Serras dos Órgãos e da Mantiqueira. As estações localizadas na vertente voltada para oceano Atlântico (barlavento) registraram as maiores médias anuais de chuva do estado, ao passo que regiões de relevo menos acidentado (Norte e Noroeste), ou com vertente voltada para continente (sotavento) das principais barreiras orográficas, registraram chuva média anual com valores inferiores à média estadual.

Satellite precipitation estimates are used as an alternative or as a supplement to the records of the in situ stations. Although some satellite precipitation products have reasonably consistent time series, they are often limited to specific geographic areas. The main objective of this study was to evaluate CHIRPS version 2, MSWEP version 2, and PERSIANN-CDR, compared to gridBR, as daily mean and extreme inputs represented on a monthly scale and their respective seasonal trends of rainfall in the Mearim River Drainage Basin (MDB), Maranhão state, Brazil. Estimates of errors were calculated (relative error, pbias; root mean square error, RMSE, and Willmott concordance index, d), and the chances of precipitation were estimated by remote sensing (RES). In addition, trends in precipitation were estimated by the two-sample Mann–Kendall test. Given the overall performance, the best products for estimating monthly mean daily rainfall in the MDB are CHIRPS and PERSIANN-CDR, especially for rainy months (December to May). For daily extremes on the monthly scale, the best RES is PERSIANN-CDR. There is no general agreement between gridBR and RES methods for the trend signal, even a nonsignificant one, much less a significant one. The use of MSWEP for the MDB region is discouraged by this study because it overestimates monthly averages and extremes. Finally, studies of this kind in drainage basins are essential to improve the information generated for managing territories and developing regionalized climate and hydrological models.

Resumo Este estudo objetivou avaliar a variabilidade da seca com base no índice Standardized Precipitation Index (SPI) em localidades da região Norte do estado do Paraná e a sua relação com o El Niño-Oscilação Sul (ENOS). Utilizaram-se as séries pluviométricas de cinco estações meteorológicas com 40 anos, obtidas junto ao Instituto Agronômico do Paraná, ao Instituto Nacional de Meteorologia e ao Sistema Meteorológico do Paraná. Destacou-se que os eventos de El Niño e La Niña influenciaram na variabilidade anual das chuvas, entretanto, mostraram associações menos significativas com extremos secos do índice SPI. Com a redução significativa dos totais de chuvas, o período de junho a agosto registrou a maior frequência das categorias de SPI moderadamente seco (18,3%), muito seco (13,0%) e extremamente seco (7,0%). As maiores frequências mensais de seca foram com intensidades, moderada, muito e extremamente seca, foram registrada na estação de Apucarana (83 eventos), seguida pelas estações de Maringá e Paranavaí (68 eventos), e Bela Vista do Paraíso (63 eventos) e Londrina (66 eventos), com as menores ocorrências de eventos de seca. Embora a literatura consultada indique a associação do aumento ou redução dos totais pluviométricos durante a ocorrência dos eventos El Niño e La Niña, as correlções de Kendall, Spearman e Pearson, e os parâmetros estatísticos (índice de concordância, erro padrão da estimativa e Teste t) empregados indicaram predominantemente baixas correlações entre os resultados obtidos de SPI - 1 mês e o ENOS em todas as regiões estudada.