Trends and Variabilities in the Historical Series of Monthly and Annual Precipitation in Cerrado Biome in the Period 1977-2010

Abstract The objective of the present study was to analyze the annual and monthly precipitation historical series of the Cerrado biome (Brazil), in order to identify local and regional trends. Different trend detection methods were used for 125 rain gauge stations throughout the Cerrado during the period 1977-2010, including LOWESS (LW), Mann-Kendall (MK), Theil-Sen (TS), and Pettitt (PT). The MK test suggested negative trends for 71% of the stations, with 14% of them statistically significant, mainly in the southerly region. Positive trends were found in 28% of the stations, where 1% was significant. The TS test suggested that, in general, the annual total precipitation in Cerrado decreased by 8,4% during the studied period. The precipitation in the dry months (JJAS) decreased in 76% of the stations, indicating an intensification of the dry season in the region. The results were consistent, suggesting a general decreasing trend in the precipitation of the biome, during the studied period.

摘要
本研究旨在分析巴西塞拉多（Cerrado）生物群落的年度与月度降水历史序列，以识别局地及区域降水趋势。研究针对1977-2010年间分布于塞拉多地区的125个雨量站，采用了包括局部加权回归散点平滑法（LOWESS, LW）、曼-肯德尔检验（Mann-Kendall, MK）、塞尔估计法（Theil-Sen, TS）以及佩蒂特检验（Pettitt, PT）在内的多种趋势检测方法。曼-肯德尔检验结果显示，71%的站点呈现降水负趋势，其中14%的站点趋势具有统计学显著性，且此类显著负趋势主要集中于南部区域；28%的站点呈现降水正趋势，仅1%的正趋势具有统计学显著性。塞尔估计法结果表明，研究期内塞拉多地区的年总降水量整体下降了8.4%。旱季（JJAS）的降水在76%的站点中均出现下降，反映出该区域旱季强度的加剧态势。上述研究结果具有一致性，表明研究期内该生物群落的降水整体呈现下降趋势。