1959—2016年华南地区极端降水事件变化特征

EXTREME PRECIPITATION EVENTS VARIATIONS IN SOUTHERN CHINA FROM 1959 TO 2016

关键词:  气候变化  极端降水  时空变化  华南地区

Key words:  climate change  extreme precipitation  spatio-temporal change  Southern China

摘要:

目的 分析我国华南地区极端降水事件的时空变化特征，探讨极端降水指数的影响因子，及其与年总降水量、大尺度大气环流的关系，并预测未来研究区域极端降水事件变化趋势，为区域水资源可持续利用和防灾减灾提供参考。方法 文章选用1959—2016年华南地区72个资料序列较长的地面气象站点逐日降水实测数据，计算11种极端降水指数并对其进行气候倾向率分析、空间分析、因子分析、相关分析、小波分析及R/S预测分析。结果 （1）从时间尺度上来看，1959年以来，研究区极端降水事件呈现增加趋势，降水强度指数SDII变化倾向率为0.34 mm/d/10a；极端降水量指数（PRCPTOT、RX1day、RX5day、R95p、R99p）变化倾向率分别为19.96 mm/10a、2.06 mm/10a、3.22 mm/10a、17.46 mm/10a和7.23 mm/10a；极端降水日数指数（R10、R20、R50、CDD、CWD）中除持续湿润日数CWD呈减少趋势以外，其他指数也呈现微弱增加趋势，其变化倾向率分别为0.31 d/10a、0.48 d/10a、0.19 d/10a、0.09 d/10a和-0.11 d/10a。从空间尺度上来看，研究区极端降水指数总体呈增加趋势，存在明显的空间差异。（2）基于因子分析方法提取了3个公共因子，累积方差贡献率为90.01 %，反映了极端降水量指数和降水强度指数对极端降水事件影响较大；相关分析也表明极端降水指数与年总降水量的相关性很好，R95p和R99p对年总降水量的贡献呈增加趋势。北大西洋涛动（NAO）对极端降水事件具有明显的影响，南海副高强度指数（SCSSHII）和西太平洋副高强度指数（WPSHII）对研究区极端降水事件贡献明显。大气环流的变化是极端降水变化的重要影响因素。（3）基于R/S分析方法表明PRCPTOT、R10、R20、R50和CDD等指数表现为强反持续性，未来将呈现减少趋势；R95p呈随机变化，未来变化趋势不明确；SDII、RX1day、RX5day、R99p和CWD等指数表现为弱持续性，即未来变化趋势与过去变化趋势一致。结论 华南地区极端降水事件总体呈增加趋势，空间差异显著，大尺度大气环流对华南地区极端降水影响明显。

Abstract:

The frequencies of extreme precipitation events are increasing worldwide in the background of climate warming, causing significant damage to agriculture, ecology, and infrastructure. The extreme weather and related societal impacts are becoming an increasingly interesting area and also has received much more attention in many regions around the world. In this study, the spatio-temporal changes of extreme precipitation events and its impact factors were analyzed, and the relationships between extreme precipitation indices and large scale atmospheric circulation was also discussed, and its extreme climatic variation in future was predicted by using linear regression, factor analysis, correlation analysis, wavelet analysis and rescaled range analysis (R/S) method based on daily precipitation data from 72 meteorological stations in Southern China from 1959 to 2016. The results showed that: (1) The extreme precipitation events in the study area had shown an increasing trend since 1959. The climatic trend of precipitation intensity index (SDII) was increased with an average of 0.34 mm/d/10a in Southern China. The change tendency rates of extreme precipitation index (PRCPTOT, RX1day, RX5day, R95p, R99p) were 19.96, 2.06, 3.22, 17.46 and 7.23 mm/10a, respectively. The extreme precipitation days index (R10, R20, R50, CDD, CWD) also showed a slight increase trend, except for the number of continuous wet days (CWD) showed a decreasing trend, and the change tendency rates were 0.31, 0.48, 0.19, 0.09 and -0.11 d/10a, respectively. From the perspective of spatial scale, the extreme precipitation index of the study area was generally increasing, and there were obvious spatial differences. (2) Three common factors were extracted based on the factor analysis method. The cumulative variance contribution rate was 90.01 %, which reflected that the extreme precipitation index and the precipitation intensity index had a great influence on the extreme precipitation events. The correlation between the extreme precipitation index and the total annual precipitation was strong. The contribution of R95p and R99p to annual total precipitation was also increasing. The North Atlantic Oscillation (NAO) had a significant impact on extreme precipitation events. The South China Sea Subtropical High Intensity Index (SCSSHII) and the Western Pacific Subtropical High Intensity Index (WPSHII) contributed significantly to the extreme precipitation events in the study area. The change of atmospheric circulation was an important factor affecting the change of extreme precipitation. (3) Based on the R/S analysis method, the indices such as PRCPTOT, R10, R20, R50 and CDD showed strong anti-persistence, and would show a decreasing trend in the future; R95p would change randomly, and the future change trend was not clear; SDII, RX1day, RX5day, R99p and CWD were characterized by weak persistence, that means future trends were consistent with past trends. In summary, extreme precipitation events in Southern China generally shows an increasing trend, with significant spatial differences. Large-scale atmospheric circulation has an obvious impact on extreme precipitation in Southern China.