Influence of Climate Variability on Erosivity in Belém (PA)

Abstract The Universal Soil Loss Equation (USLE) is a model in which soil loss is the product of several indices, including rainfall erosivity (R). This factor identifies when the greatest risk of water erosion occurs. The objective of this study was to analyze the influence of ENOS (El Niño Southern Oscillation) and Atlantic Dipole on the R factor in Belém (PA). Erosivities from 1986 to 2015 were classified according to intensity. ENSO events were also classified to evaluate a possible influence of their amplitude. The Niño Oscillation Index (ION) was used to verify the occurrence of ENSO. In order to analyze the Atlantic Dipole, the TNA (Tropical Northern Atlantic) and TSA (Tropical Southern Atlantic) indices were used, because this phenomenon directly interferes in the region’s main atmospheric system, the Intertropical Convergence Zone (ZCIT). Pearson correlation analysis and linear regression were determined between R and climatic indexes. Thus, lower erosivities were observed in years of intense El Niño, obtaining higher correlation coefficients. Coincidence of intense La Niña with Negative Dipole also represented higher correlation coefficients, meaning the increase of erosivity. There was a weak correlation of erosivity during Positive Dipole.

摘要：通用土壤流失方程（Universal Soil Loss Equation, USLE）是一类将土壤侵蚀量表示为多指标乘积的模型，其中降雨侵蚀力（rainfall erosivity, R）为关键组成因子，该因子可用于识别水蚀风险最高的时段。本研究旨在分析厄尔尼诺南方涛动（El Niño Southern Oscillation, ENOS）与大西洋偶极子对巴西帕拉州贝伦地区降雨侵蚀力（R）因子的影响。研究对1986年至2015年的降雨侵蚀力按强度等级进行分类，并对厄尔尼诺南方涛动事件按振幅分级，以评估其潜在影响。本研究采用尼诺涛动指数（Niño Oscillation Index, ION）验证厄尔尼诺南方涛动的发生情况；针对大西洋偶极子现象，则选用热带北大西洋（Tropical Northern Atlantic, TNA）与热带南大西洋（Tropical Southern Atlantic, TSA）指数开展分析，因该现象直接干扰研究区域的主要大气系统——热带辐合带（Intertropical Convergence Zone, ZCIT）。本研究通过皮尔逊相关分析与线性回归，探究了降雨侵蚀力（R）与各气候指数间的关联。结果显示，强厄尔尼诺年份的降雨侵蚀力更低，且相关系数更高；强拉尼娜与负大西洋偶极子同时出现时，相关系数同样较高，表明此时降雨侵蚀力有所提升；而正大西洋偶极子期间，降雨侵蚀力仅表现出弱相关性。