Prediction of Climate Change Trend Based on Rescaled Range Analysis and Non-periodic Cycle Analysis——A Case Study in Lanzhou City

Based on two methods of R/S and non-periodic cycle analysis,the values of Hurst parameter H,fractal dimension D and non-cycle average cycle length of temperature and precipitation at time series in Lanzhou City were calculated,and then the variation trends,long-term memory effects and memory cycles of temperature and precipitation at the time series were analyzed.The results show that the values of H and D of average seasonal and annual temperature varied in ranges of 0.5-1 and 1-1.5 respectively,there was a fractal structure,and average seasonal and annual temperature was in a continuous increase trend.Average cycle lengths of average annual and spring,summer,autumn and winter temperature at time series were 9 years,4 years,8 years,5 years and 6 years respectively.Precipitation in spring and winter will continuously decrease but increase in summer.H and D of average annual and autumn precipitation series with long-term negative correlation will vary in ranges of 0-0.5 and 1.5-2 respectively,the change process has an anti-persistent character,the average annual and autumn precipitation in the future will in an increase trend,average cycle lengths of average annual,spring,summer,autumn and winter precipitation at time series will be 9 years,7 years,10 years,12 years and 13 years respectively.Precipitation in the past will affect that in the future for a long time.The study revealed that the methods of R/S and non-periodic cycle analysis are new,scientific and reliable in predicting regional climate change.