Abstract:

The observed precipitation and temperature data of 31 meteorological stations from 1965 to 2013 in Nujiang and Lancang river basins in Yunnan Province were collected and the standardized precipitation evapo-transpiration index (SPEI) was employed to analyse the drought processes of each bio-climate zone in the two basins. The occurrence frequencies and severities of the meteorological droughts were computed in annual, seaso- nal and monthly scale. The spatial and temporal change and the intensity of drought occurrence in the study area were revealed. The results show that there was a significant increasing trend in seasonal and monthly drought since the late 1970s; the drought occurred without obvious spatial distinction among the bio-climate zones. In the recent 50 years, the significant increase of drought in the study area may be attributed to the significantly raising in temperature, rather than the lightly decline of the precipitation.

Key words: standardized precipitation evapotranspiration index (SPEI), meteorological drought, Nujiang river, Lancang rive

摘要：

基于怒江、澜沧江云南段31个气象站点1965—2013年的月降水、气温资料, 计算两个流域各生物气候区的标准化降水蒸散指数(SPEI)。分析近50年的年、季节、月尺度的干旱过程、干旱发生频率及强度, 揭示怒江、澜沧江云南段干旱发生的时空和强度演变特征。结果表明, 自20世纪70年代后期以来, 研究区季节、月尺度干旱整体上呈显著增加趋势, 尤其是冬季; 两个流域内各气候区干旱特征的空间分异不明显, 干旱发生与全省性的大范围干旱发生较为一致; 近50年来, 研究区气温的显著升高可能比降水的微弱减少对其干旱变化贡献更大。

关键词: 标准化降水蒸散指数(SPEI), 气象, 干旱, 怒江, 澜沧江