干旱区生态环境知识资源中心

Drought evolution from 1960 to 2010 and its teleconnections were analyzed by utilizing the monthly Standardized Precipitation Evapotranspiration Index (SPEI) in the arid region of northwestern China. To assess the temporal pattern of drought as multi-scalar events, the SPEI was calculated for short-term (1 and 3 mo), medium-term (6 and 12 mo), and long-term droughts (24 and 48 mo). The results showed (1) step changes occurred in 1986; droughts occurred frequently before 1986, and wet periods prevailed after 1986. Generally, the period of 1973-1983 showed the highest drought activity, while 1993-1998 showed the lowest. (2) Annual and seasonal SPEI demonstrated significant upward trends, especially for the stations around the Tarim River Basin, implying that the study area had become wetter. (3) Interannual periods and decadal periods were observed for the whole study area and sub-regions. Moreover, patterns of period characteristics became more apparent at longer time scales. (4) The Indian Ocean Basin-Wide mode (IOBW) and Pacific Decadal Oscillation (PDO) may be the dominant forces, with the largest correlation coefficients in the whole study area. For the Xinjiang region, the simultaneous Arctic Oscillation (AO) and North Atlantic Oscillation (NAO) play an important role in drought evolution, especially from January to March. Lag times between climate indices and SPEI may exist in this arid region, and current droughts may be affected by the preceding climate indices.