Trend of Observed and Projected Extreme Climate Indices in Minas Gerais State

Abstract Climate extreme indices of temperature and precipitation over Minas Gerais are analyzed by using 19 General Circulation Models belonging to the CMIP5 in 1948-2005 period and during the periods of 2041-2070 and 2071-2100. The Reanalysis (NCEP / NCAR) data is also used for the 1948-2005 period for comparison with simulations models, as well as, conventional meteorological station data for the 1961-2014 period. Trend analysis of these indices is made through the statistical Mann-Kendall and Sen’s Slope estimator for spatial means of the indexes in two study areas: north and south of Minas Gerais (NMG and SMG, respectively). Generally, the temperature-related indices have higher tendencies of values than the precipitation rates, are significant in most and show an increase of hot days and nights and a reduction of cold days and nights in Minas Gerais. Regarding to precipitation, even with few significant amounts, one can observe an increase in dry conditions in the NMG region and humid conditions in the SMG, intensifying the existing differences in the state. Therefore, these results may have important implications for studies of climatic extremes and monitoring activities of the extreme features of temperature and rainfall in Minas Gerais.

摘要：本文针对巴西米纳斯吉拉斯州的气温与降水气候极端指数开展分析。研究采用隶属于第五次耦合模式比较计划（Coupled Model Intercomparison Project Phase 5, CMIP5）的19个大气环流模式（General Circulation Models, GCM），覆盖1948-2005年、2041-2070年及2071-2100年三个时段。此外，本文还使用1948-2005年的NCEP/NCAR再分析数据与模式模拟结果进行对比，并采用1961-2014年的常规气象站观测数据辅助分析。针对米纳斯吉拉斯州北部（NMG）和南部（SMG）两个研究区域的指数空间均值，本文采用曼-肯德尔（Mann-Kendall）检验与森斜率（Sen’s Slope）估计器对上述极端指数进行趋势分析。整体而言，该州与气温相关的极端指数变化幅度高于降水相关指数，多数指数通过了显著性检验，表现为热日、热夜天数增加，冷日、冷夜天数减少。就降水极端指数而言，尽管通过显著性检验的案例较少，但仍可观测到NMG区域趋于干旱、SMG区域趋于湿润的变化趋势，这将加剧该州内部已有的气候差异。综上，本研究结果对米纳斯吉拉斯州的气候极端事件研究以及气温、降水极端特征的监测工作具有重要参考价值。