Abstract:

A general survey of all typhoons that entered the 24 h cordon during 1961-2015 was conducted, and 245 typhoons between 22°N and 38°N (hereinafter named the study region) were selected to make a statistical analysis, the results show that these typhoons entering the study region had significantly inter-annual variation. Typhoons were mainly concentrated in the period from April to November and distributed in a normal distribution with a peak in August. Depending on the typhoon’s track and intensity, these typhoons were separated into five categories: offshore steering type, offshore northward type, landing steering type, landing northward type and landing weakening type, then typhoons with rainfall amount exceeding 50 mm in Rizhao were selected and analyzed. The results indicated that there were 33 typhoons which caused rainstorms in Rizhao and they mainly occurred in July and August. Among those typhoons, the landing weakening type caused the most rainstorms and occurred 11 times, and followed by the landing northward type occurring 8 times, and the third was the offshore steering type typhoon and the landing steering type typhoon occurring 5 times respectively, while the least was the offshore northward type typhoon occurring only 4 times. The landing weakening type typhoon caused more heavy rainstorms with a rainfall amount exceeding 100 mm in Rizhao and occurred 4 times, followed by the offshore steering type and the landing northward type typhoon which occurred 3 times respectively, while the least was the offshore northward type and the landing steering type occurring only once. The landing northward type typhoon caused disaster seriously, they had the best chance to cause heavy rainstorm and strong wind and in fact they occurred 3 times, followed by the landing weaken type typhoon which occurred 2 times, while the least was the offshore steering type and the landing steering type occurring only once respectively.