50年来中国沙尘暴的多时间尺度变化特征

采用中国强沙尘暴序列及其支撑数据集，对1958—2007年中国沙尘暴的时间序列进行小波分析，揭示了中国沙尘暴多时间尺度的复杂结构和总体变化趋势，给出不同时间尺度下沙尘暴变化的突变点，并对未来变化趋势进行了展望。结果表明：中国沙尘暴呈明显振荡式减少趋势，距平值在1985-1986年出现转折；50a中沙尘暴变化呈现从多到少的振荡形式，其减少趋势的振荡变化主要受6—8a和2～3a尺度变化的叠加影响，6～8a尺度变化出现了4次突变；1966、1985和2001年沙尘暴出现较强的变化是多时间尺度叠加的结果。2008年后的10～15a中，沙尘暴总体减少趋势将减缓，其平均值在1958-2007年平均值和1983-2007年平均值之间，2011年前后可能出现一个接近2001和2002年平均情况的峰值，随后仍和缓减少。

Multi-Timescale Variation of Sand-Dust Storm in China during 1958 2007

By using the observational data from meteorological stations, wavelet analysis has been con-ducted to the time series of sand-dust storm station-hour occurred in China during the past 50 years (1958-2007). The complicated multi-timescale structure and general tendency of the time series have been revealed. Turning points of the time series on different time scales have been analyzed. Also future outlook on the changes of sand-dust storm is presented. The research results indicate that the sand-dust storms in China showed an apparent deceasing trend accompanied by obvious oscillations; and there was a turning point in the anomaly series in 1985-1986. Wavelet analysis indicates that an oscillation occurred in the past 50 years, in which the sand-dust storms changed from more to less than normal. The fluctuatedly decreasing trend was mainly governed by 6-8 years' and 2-3 years' time scales, The sig-nificant changes of sand-dust storms in 1966,1985, and 2001 resulted from the superposition of multi-time scales. An outlook on sand-dust storms after 2008 show that in the future 10-15 years, the gener-ally decreasing of sand-dust storms will be slow down, the mean value will range between the averaged value of past 50 years(1958-2007) and that of the past 20 years(1988-2007) ,namely between 1 100 and 2 000 station-hour, under the circumstances that the observation stations and the number of sta-tions keep unchanged. As influenced by oscillations,there might be a peak value around 2011, which is close to the mean values of 2001 and 2002 ,also approximates to the mean value of the past 50 years. Afterwards,the sand-dust storm will still gently decrease.