Abstract:
In order to systematically reveal the variation characteristics of extreme temperature and precipitation events in Kunming, based on the data of daily maximum and minimum temperature and daily precipitation from 1951 to 2016 at Kunming meteorological stations, the variation trends, mutation characteristics and periodic change of 16 extreme temperature indices and 11 extreme precipitation indices have been analyzed with methods of the linear regression analysis, Mann-Kendall abrupt change test, and Morlet complex wavelet analysis. Firstly, the results of variation trends are as follow: there are significant downward trends of extreme temperature indices of FD, TN10p, TX10p, CSDI and DTR. However, there are significant upward trends of extreme temperature indices of TNx, TNn, SU, TR, TN90p, TX90p and WSDI. There are non-significant upward trends of extreme temperature indices of TXx, TXn, ID and GSL. Moreover, the monthly minimum temperature indices increases faster than the monthly maximum temperature indices. The extreme precipitation indices of R95pTOT, R99pTOT, CDD, CWD, Rx1day, Rx5day and SDII show upward trends whereas the indices of R1, R10, R20 and PRCPTOT show downward trends. Secondly, the results of mutation test are as follows: most of the abrupt change years of extreme temperature and precipitation indices are from the late 1980s to early 21st century. And there are different mutation years of extreme indices. The extreme indices of cold events show significant downward trends after the mutation years, while the extreme indices of warm events show significant upward trends after the mutation years. In addition, the periodic results of wavelet analysis are as follows : the extreme temperature indices present 2—6 quasi-periods of ranging from 4 to 57 years, with 1—3 main periods ranging from 6 to 55 years. The extreme precipitation indices present 4—6 quasi-periods of ranging from 4 to 57 years, with 1—3 main periods ranging from 15 to 57 years. Therefore, there are parellel or similar main periods for part of the extreme temperature and precipitation indices.