Spatiotemporal Variation Of Meteorological Drought In North Xinjiang Province From 1961 To 2012

Variation of drought have a significant influence on agricultural development and ecological security in arid and semi-arid region of Northweast China. The spatiotemporal variation and the driving force of drought were investigated based on meteorological data(temperature, precipitation, relative humid, sunshine hours, and et al.) and trend analysis, wavelet analysis, ensemble empirical mode decomposition. The results are as follow:(1) The comlex meteorological drought composite index(CI) can adequately characterize variation of drought in North Xinjiang Province(NX) based on comparatively analysis between calculation results and historical datasets, which not only reflected by robust ability of drought detection and lower error rate, but also confirmed by strong sensitivity to variation of precipitation.(2) The drought coverage area and frequency experienced a decreasing trend, the drought intensity presented a weaking trend from 1961 to 2012. Morever, the drought coverage area, frequency and intensity have multiscale periods(inter-decadal and inter-annual variation) and abrupt change(maily happened in 1980 s and early 1990s), which indicated the multiscale characteristics of drought in NX. Dought is worst in summer, serious in spring and autumn, light in winter. However, the decreasing trend exhibited most significant in winter.For spatial variation, drought was light in northwest region and serious in southeast of NX. Under the condition of climate change, drought gradually became light during tha past 52 years, especially exhibited more significant in south central region of NX. Nevertheless, a noticeable point is that extreme drought happened frequently.(3) The increasing trend of temperature and precipitation and the decreasing trend of evapotranspiration have a humidifying effect on the light trend of drought in the study region. The Arctic Oscillation and Southern Oscillation Index have a significant anti-phase relationship with interannual and interdecadal variation of drought. Whereas, variation of drought responsed to North Atlantic Oscillation Index and Pacific / North American Oscillation Index in-phase on different time-scales over the study period.Summarly,the results in this study suggested that drought has been alleviated during past half century, especially more significant after 1980 s. The transformation from warm-drying to warm-wetting trend contribute most to the alleviating condition of drought under the condition of climate change. However, extreme drought also happened frequently, whicih necessitate countermeasures to minimize the risk of drought disease. This study investigated spatiotemporal variation of drought and its correlation with climatic factors and oscillation index, which can enrich scientific research of drought in Xinjiang and provide scientific basis and theoretical support for drought countermeasures.