气候变暖背景下中亚地区极端降水事件变化及其对植被覆盖的影响

Variation of Extreme Precipitation Events and Their Impacts on Vegetation Coverage in Central Asia Under Climate Warming

为了解气候变暖背景下中亚地区极端降水事件的时空变化特征及其对植被覆盖的影响,基于1982—2014年GLDAS气象资料和GIMMS NDVI数据,采用线性趋势、滑动平均、M-K非参数检验、相关分析等方法分析了中亚地区降水极值时空变化以及和NDVI之间的关系。结果表明:近33 a来,中亚地区生长季气温呈显著上升趋势,各极端降水指数和降水量均呈弱增加趋势。除持续干旱日数(CDD)外,其他极端降水指数在1990s发生了气候突变,进入21世纪以来,极端降水频度和强度较之前更大,降水更为集中。极端降水指数多年均值空间分布特征与降水量较为一致,表现为从西南到东北呈逐渐增加趋势,除CDD外,各极端降水指数呈显著增加趋势的区域范围大于降水量。生长季NDVI与5日最大降水量(RX 5day)、降水强度(SDII)、中雨日数(R 10)、大雨日数(R 20)、极强降水量(R 99p)呈极显著正相关(p<0.01),与CDD和生长季均温(TEMP)呈负相关(p>0.05),降水为中亚地区植被生长的主要控制因子。生长季NDVI与除CDD之外的各极端降水指数呈显著正相关的区域主要集中在降水量高值区。

In order to understand the spatiotemporal variation characteristics of extreme precipitation events in Central Asia under the background of climate warming,based on the data of GLDAS and GIMMS NDVI from 1982 to 2014,linear trend,moving average,M-K non-parametric test and correlation analysis were used in this research.The results showed that the temperature of growing season in Central Asia has increased significantly in the past 33 years,and the precipitation and each extreme precipitation index in growing season were weakly increasing;in addition to the continuous dry days(CDD),other extreme precipitation indexes experienced a sudden change in the 1990s;since the beginning of the 21st century,the frequency and intensity of extreme precipitation have been greater than before,and precipitation has become more concentrated;the spatial distribution characteristics of the average extreme precipitation index were consistent with the precipitation,which showed a gradual increasing trend from southwest to northeast;except for CDD,the area of the extreme precipitation index showing a significant increase trend was larger than that of the precipitation;the mean NDVI value in the growing season was significantly positively correlated with the extreme precipitation indexes other than CDD,which was extremely significantly positively correlated with maximum precipitation for 5 consecutive days(RX 5day),precipitation intensity(SDII),number of heavy precipitation days(R 10),number of very heavy precipitation days(R 20),extremely wet days(R 99p)(p<0.01),and was negatively correlated with CDD and the average temperature of the growing season(TEMP).Precipitation is the main control factor for vegetation growth in Central Asia.The regions where NDVI and the extreme precipitation indexes other than CDD were significantly positively correlated mainly concentrated in areas with high precipitation.