Abstract:

Precipitation has been a hot topic in the study of climate change and forecast. Heavy precipitation days reflect the condition of concentrated precipitation that has a great significance. Based on the daily precipitation data of 27 rainfall stations from 1957 to 2013 in Liaoning Province, trend coefficient method was used to calculate the trend of heavy precipitation days. Mutation was tested by the Mann-Kendall method. The cycle of heavy precipitation days was explored using the Morlet wavelet method. With the help of the ArcGIS software, this study analyzed the spatial distribution of heavy precipitation days. Both Kriging and inverse distance weighted (IDW) interpolation method were used in this study. The results show that heavy precipitation days decreased from the southeast to the northwest in Liaoning Province. Maximum days of precipitation were found in Dandong. Inter-annual variation of heavy precipitation showed a cycle of about 38 years. Overall the number of heavy precipitation days decreased, but not significantly. Only a few areas passed the significance test. In central Liaoning Province the change slightly lagged, and changes in western Liaoning Province were complex. Seasonally, a 38 year cycle was detected for the spring and the summer—the same as the annual cycle, and a 15 year cycle was found for the autumn. Inter-annual variation of heavy precipitation days showed a slight decreasing trend, and it slightly differed in different seasons.

Key words: Liaoning Province, heavy precipitation days, trend coefficient, wavelet analysis