河西走廊沙尘暴频数的时序分形特征

对1961-1990年河西走廊沙尘暴频次资料进行的分形研究发现,沙尘暴发生的时序分布具有分形特征,计算所得其相空间的关联维数为5.52,表明要恰当地描述河西地区沙尘暴变化特征,需构造至少6个状态变量的动力学系统;在分析了沙尘暴频数时间序列的Kolmogorov熵为0.18、平均可预测时间尺度为5~6 a的基础上,运用R/S分析方法对1961-1990年中各时段沙尘暴的变化趋势进行了预测,预测结果与实际沙尘暴的变化趋势十分吻合,表明上述方法是进行河西地区沙尘暴时间序列分形研究的有效途径。

Time-Series Fractal Characteristics of Sandstorm Frequency in Hexi Corridor

Many researches have been made about sandstorm based on correlative data,and the work mainly focused on the history data's arrangement and statistical analysis,but the inherent nonlinear trait of sandstorm is studied less.Based on the annual frequency data of sandstorm occurring from 1961-1990 in Hexi corridor,the time-series phase space is reconstructed and Kolmogorov entropy is calculated.The results show that sandstorm time-series has fractal characteristics and its correlative dimension is 5.52,which indicates that there should have at least 6 independent variables for describing sandstorm change characteristics and reconstructing a dynamic system.Kolmogorov entropy of sandstorm time-series is 0.18,which indicates that sandstorm dynamic system is chaotic and the forecasting time-scale is about 5~6 years.Based on R/S analysis of every sandstorm period from 1961-1990,all the periods have persistence change except the period of 1973-1978,and the results are quite consistent with actual changing trend of sandstorm time-series.The method is effective for studying fractal characteristics of sandstorm time-series in Hexi corridor.