Contribution of typhoon over coastal waters to summer rainfall in eastern China

Abstract

Now, it is difficult to consider the typhoon rainfall in the short-term climate prediction. This is mainly because the typhoon is a strong synoptic scale system and it does not match the scale of the short-term climate forcast. It is a factor restricting the great improvement of forecast. By using station precipitation data in eastern China from 1960 to 2011 and CMA-STI Best track dataset for tropical cyclones over the western north pacific, we analyse the strength variation of typhoon influence from month and quarter scale in summer by determining the typhoon influence index, then discuss the contribution of typhoon rainfull to summer rainfall in eastern China. 1) On average, the typhoon is enhanced from June to August, it is weakest in June, and strongest in August. 2) From the distribution of typhoon rainfall and its proportion of the total precipitation in eastern China, totally, the tyhoon rainfall is higher in eastern region than in the western region on the same latitude, and it is higher in southern region than in the northern region on the same longitude. The ratio of typhoon rainfall to the total precipitation could reach up to 10% in the South of the Yangtze river region. The typhoon rainfall can also reach up to 100 mm in the southeast coastal area in July and August, which can amount to 40% of the total precipitation during the month. 3) The correlation of the typhoon influence index with summer precipitation shows that the typhoon’s influences on the precipitation in eastern China are different spatiotemporally. The results indicate that the negative correlation is in southern part of China in June, the positive correlation is the southeast coastal area in July, the positive correlation is in the south China in August, and the negative correlation is in the middle and lower reaches of the Yangtze river region, which are mainly due to the typhoon, summer moonsoon, and high pressure in the north-east pacific subtripics respectively.