基于ESMD方法的上川岛降水多尺度特征分析

An Analysis of Multi-scale Characteristics of Precipitation on Shangchuan Island Based on the ESMD Method

利用极点对称模态分解(ESMD)方法,对1958—2020年上川岛的年降水序列进行多时间尺度分析,并用小波分析、M-K检验法进行对比验证。结果表明:(1)上川岛年降水量变化以年际尺度周期变化为主,有2.6和6.3年的周期振荡;年代际尺度上以10.5和31.5年周期振荡为主。(2)2.6、6.3和10.5年尺度下的突变时间分别为1986、1995和2000年,31.5年尺度上没有明显的突变时间。(3)利用ESMD方法可以将不同时间尺度的序列有效分离,便于诊断多时间尺度的周期、趋势和突变特征。

The method of Extreme-point Symmetric Mode Decomposition(ESMD)is used to perform a multiple time scale analysis of annual rain series for the island of Shangchuan from 1958 to 2020 and the methods of wavelet analysis and Mann-Kendall test are used to compare and verify the results.The result is shown as follows.(1)For the island,annual precipitation amount varies at a predominantly interannual scale,oscillating at periods of 2.6 and 6.3 years.It also varies at the interdecadal scales of 10.5 and 31.5 years.(2)On the annual scales of 2.6,6.3 and 10.5 years,abrupt changes took place in 1986,1995 and 2000,respectively,but the scale of 31.5 years did not show any significant abrupt change.(3)With the ESMD method,series with different time scales can be efficiently isolated and the characteristics can be diagnosed of periods,tendency and abrupt changes on multiple time scale.