Abstract:

Based on daily precipitation data at 35 observation stations during flood season from 1961 to 2012 in Shandong province, temporal and spatial characteristics of rainstorm day and intensity were analyzed by a mathematical statistical method. Meanwhile, a mean generating function model was established in an experiment of rainstorm prediction and was used to predict rainstorm. The results show that the rainstorm day and intensity during flood season from 1961 to 2012 in Shandong province are in a decreasing trend, and both are not statistically significant at the 0.05 level. Annual mean rainstorm days during the flood season are 2.2 days from 1961 to 2012 in Shandong province, and there are two cycles of 3.4 years and 8.0 years. Annual mean rainstorm intensity is 67.8 mm·d^-1, oscillating with cycles of 2.3 years, 3.3 years, 6.9 years and quasi-12 years. There are no abrupt changes for rainstorm day and intensity during the flood season from 1961 to 2012 in Shandong province. Particularly, the annual mean rainstorm day and intensity during the flood season all decrease from the mid-later 1970s to late 1980s. The rainstorm day and intensity all increase gradually from northwest to southeast in Shandong province. The high frequency and strong intensity rainstorm events and continuous rainstorm events usually occur in the south of Shandong province, the south and east of Shandong peninsula. Prediction of rainstorm suggests that the mean generating function model can correctly simulate climate trend of rainstorm during the flood season from 2003 to 2012 in Shandong province, and it also has a good ability in the rainstorm prediction.

Key words: Flood season, Rainstorm day and intensity, Mean generating function