Abstract:

 Based on daily and hourly precipitation data at 61 national weather stations in Liaoning province from 1960 to 2011, the spatial and temporal climate change characteristics of heavy rainstorm were analyzed statistically. The result shows that the number of average annual rainstorm is 6.5 days, and annual average stations where heavy rainstorms were observed are 17.5 stations. High-incidence areas of two rainstorms are located in the southeast of Liaoning and southwestern to southern seacoast of Liaoning province, respectively. Regional and local heavy rain easily occurs in the area of high-incidence rainstorm because of influence of typhoon, Jianghuai cyclone, North China cyclone, Mongolia cyclone etc. and local geographical conditions in the southeast of Liaoning province. As a result, the frequency of heavy rain is high and precipitation changes largely. Extreme of precipitation and intensity both are large, and the strongest rainfall is up to 212 mm/h^-1 and appears in Fengcheng. On the other hand, a regional heavy rain also easily occurs in the area of high-incidence rainstorm because of influence of typhoon, North China cyclone and topography, so extreme precipitation and intensity are also larger in the south to southwest of Liaoning province. However, the centers of maximum precipitation and extreme intensity are not consistent with that of the number of rainstorm day. Extreme of regional rainstorm is a major contribution to that of rainstorm. Hourly variation of precipitation intensity has a peak at 08:00 and a valley at 20:00. Heavy rainstorm day mainly appears from the last ten days of July to the first ten days of August, and it is higher in August than in July. The first and last regional heavy rains are influenced by Jianghuai cyclone and both occur in the south of Liaoning province. It is a significant cycle for the heavy rain day and its main inerdecadal cycle is 10 years, while main cycles of regional and local heavy rain are 36 years and 10 years respectively. Forecast suggests that the heavy rain still often occurs in the next 6 years in Liaoning province, especially the local heavy rain.

Key words: Heavy rainstorm, Extreme, Cycle