Distributions of Seasonal Average Temperature and Precipitation Trends in Brazilian Biomes

Abstract The aim of this work was to identify climate trends in seasonal time series for precipitation and average air temperature, observed in 243 municipalities distributed over the Brazilian biomes. The data were obtained from National Institute of Meteorology (INMET). The Mann-Kendall and Pettitt tests were applied. The statistical results and the seasonal trend distributions maps allow us to observe that all biomes exhibit non-significant trends in the both meteorological variables. The average temperature was the variable that showed the highest number of positive trends (72 in autumn, 81 in winter, 80 in spring and 92 in summer). Such trends were mostly detected during the decade of 1990 and in the Amazônia and Cerrado biomes. Negative trends were observed in the Caatinga and Cerrado biomes for the seasons of autumn, winter and spring. For the precipitation, negative trends we observed in all the four seasons, during the decades of 1980, 1990 and 2000. Positive trends were observed in the decade of 2000 and during the autumn and winter seasons, especially in the Amazônia and Mata Atlântica biomes. These trends seem to be related to the El Niño and La Niña events.

摘要：本研究旨在识别分布于巴西各生物群落的243个自治市所观测到的降水与平均气温的季节时间序列的气候趋势。所用数据源自巴西国家气象局（National Institute of Meteorology, INMET）。本研究采用曼-肯德尔（Mann-Kendall）检验与佩蒂特（Pettitt）检验开展分析。统计结果与季节趋势分布地图表明，所有生物群落的两类气象变量均未呈现显著趋势。平均气温是正向趋势数量最多的变量：秋季72个、冬季81个、春季80个、夏季92个。此类正向趋势主要集中于1990年代，且多在亚马逊（Amazônia）与塞拉多（Cerrado）生物群落中被检测到。卡廷加（Caatinga）与塞拉多生物群落的秋、冬、春三季则观测到负向趋势。就降水而言，1980、1990及2000年代的四季均存在负向趋势；而2000年代的秋季与冬季则呈现正向趋势，尤其在亚马逊与大西洋森林（Mata Atlântica）生物群落中表现显著。上述趋势似乎与厄尔尼诺（El Niño）及拉尼娜（La Niña）事件存在关联。