【摘要】 利用R/S分析方法分析了分别来源于美国North Dakota(1980～2000年)及我国常德市(1990～1999年)的降水酸度月均值时间序列,证实了降水酸度时间序列中存在长程相关性.其Hurst指数H>0.5,表明其变化表现为分形布朗运动,各月份降水酸度值是相互关联的.长程相关的时间可达8～9年,表明长程相关性是降水酸度趋势预测中必须考虑的重要因子。更多还原

【Abstract】 Rescaled range analysis (R/S) is applied to verify the presence of long-term dependence of monthly rain acidity series. Two series, which are respectively from North Da-kota( 1980 - 2000), USA, and Changde (1990 - 1999), China, are checked. The results show that monthly rain acidity series exhibit fractal Brown motion with Hurst exponent H> 0. 5, implying a long-term dependence in the series and the succeeding monthly pH are not independent of each other. The dependence duration may persist 8-9 years, implying that the long-term dependence may be a very important factor and must be considered in the trend prediction of rain acidity.更多还原