Pa、SPI和SPEI干旱指数对青藏高原东部高寒草地干旱的响应比较

利用甘南州及周边地区33个气象台站1965-2013年的降水和温度数据,比较分析了降水距平指数(Pa)、标准化降水指数(SPI)和标准化降水蒸散指数(SPEI)对高寒草地干旱响应的有效性,并结合历史旱灾统计资料进行了结果验证。结果表明,从Pa指数、SPI指数、SPEI指数与草地NDVI的相关分析可以看出,SPI_6和SPEI_6与草地NDVI关系较好,Pa、SPI_1、SPEI_1、SPI_3、SPEI_3不足是波动不稳定,SPI_(12)、SPEI_(12)对干旱的反应表现出一定的滞后性。SPI_6和SPEI_6均适于定量研究高寒草地的干旱状况,结合历史统计资料验证,两项干旱指数监测效果相对较好。本研究结果将为有关青藏高原高寒草地的干旱研究提供有益的参考。

The responses of Pa,SPI, and SPEI to dry climate in alpine meadows of eastern Qinghai-Tibet Plateau

Using precipitation and temperature data from 33 meteorological stations around Gannan in 1965-2013, the percentage of precipitation anomalies (Pa), standardized precipitation index (SPI), and standardized precipitation evapotranspiration index (SPEI) were calculated.To select a suitable index to describe dry climatic factors in alpine meadows, we analysed the response of these indexes to drought.In addition, verification was conducted by comparing historical disaster statistics with the drought indexes.The correlation analysis of SPI, SPEI, and Pa with grassland normalized difference vegetation index (NDVI) showed that the reaction of Pa, SPI1, SPEI1, SPI3, and SPEI3 to precipitation was too sensitive;however, SPI12 and SPEI12 were slightly hysteretic.SPI6 and SPEI6 were both well suited to quantitatively evaluating the dry climatic factors in this area.Based on historical statistics, two drought indexes were somewhat better.These results provide effective data in support of further research on drought risk analysis in alpine grasslands.