Abstract
Rainfall expresses one of the most complex climate factors in Southeastern Brazil. Understanding the dynamics and temporal trends of rainfall represents a significant challenge due to regional and even global mechanisms, such as FS (Frontal Systems) and the SACZ (South Atlantic Convergence Zone), and the interaction with the Atlantic and Pacific Oceans. The present study aimed at analyzing the pluviometric tendencies in São Carlos/SP, in the countryside of São Paulo State. Laplace trend test was used to comprehend the temporal evolution of daily rainfall in the region in the historical series 1979-2017, in seven pluviometric stations (climatological or surface stations). Significant fluctuations in interannual trends and between seasons were observed. However, it was noted that the beginning of the 1980s showed positive trends, whereas, as of the year 2000, most of the stations demonstrated negative trends, indicating a reduction in daily rainfall volume due to the great tropical climatic variability of Brazil. Emphasis should also be given to the regional and local effects, such as elevation and urbanization, respectively, which corroborate such differences among the analyzed stations. This methodology is of considerable value for the observation of pluviometric trends, and future studies can validate such a tool in climatological studies.
Highlights
Several pluviometric anomalies occur in Brazil, such as in the northeastern drought polygon and extreme events in the southern portion of the country, where interactions between tropical and extratropical systems are present, as well as the South Atlantic Convergence Zone (SACZ) and frontal phenomena, which result from the air masses that predominate in the region
It is noteworthy that frontal systems (FS) and the South Atlantic Convergence Zone (SACZ), among other atmospheric mechanisms, represent some of the primary elements associated with rainfall in the region
The chosen method (Laplace test) showed to be effective in annually guiding the rainfall distribution in climatological seasons. Considering these aspects, the present study verified the temporal behavior of rainfall in São Carlos/SP in order to interpret the pluviometric trends for the region, since discussions regarding its intensification have shown to be of great interest in regional climatology
Summary
Several pluviometric anomalies occur in Brazil, such as in the northeastern drought polygon and extreme events in the southern portion of the country, where interactions between tropical and extratropical systems are present, as well as the South Atlantic Convergence Zone (SACZ) and frontal phenomena, which result from the air masses that predominate in the region. These interactions are of significant interest in regional planning due to the high degree of interference, impact, and spatiotemporal repercussion (Sant’Anna Neto & Zavattini, 2000). In the Brazilian Southeast, the rainfall trends influence the tendencies of temperature increase/decrease (Drumond & Ambrizzi, 2008; Evangelista et al, 2007; Kayano & Capistrano, 2014; Pscheidt & Grimm, 2009; Vásquez et al, 2018)
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