Analysis on the Precipitation in Multiple Scales in Xi’an of China

Abstract

Based on the data of precipitation from 1951 to 2014 in Xi’an,Shanxi Province,China(hereinafter referred to as Xi’an),after analyzing the characteristics of changes in precipitation over the last 64 years,the multiple scale analysis of annual precipitation and flood season precipitation are analyzed by wavelet analysis in Xi'an.The conclusions are as follows:(1)Flood season precipitation accounts for 79.32% of annual precipitation, and the correlation coefficient is 0.94,so,the contribution of precipitation in flood season to annual precipitation is very great.(2) Annual precipitation and flood season precipitation shows a decreasing trend, with a decreasing rate of -11.3mm/10a and -3.17mm /10a, respectively,which shows 72% of the annual precipitation decreases in the non flood season.(3)Annual precipitation sequence and flood season precipitation sequence have the similar main cycle in Xi'an.Their first main periods are 29 years and 31 years, respectively, and the second, the third,the forth main cycles all are 13 years, 6 years and 3 years.(4)Over any time scale,the annual precipitation and the precipitation in flood season will be into a less period after 2014.Since the oscillation intensities of the first and the second main cycles of annual precipitation is basically same,the possibilities of the less period of annual precipitation continuing to 2020 or 2017 are the same.However,the oscillation intensity of the first main cycle of precipitation in flood season is much greater than that of the second main cycle,so the probability of the less period of precipitation in the flood season is more likely to continue to 2020 than 2017.