Characteristics Of Tropical Cyclone Extreme Precipitation And Its Preliminary Causes Over Mainland Of The South China

Based on 184 meteorological-station daily precipitation data during 1960-2014 over mainland of the South China(Guangdong and Guangxi), Tropical Cyclone(TC) Best Track Dataset, ERA-interim Reanalysis Dataset and ERA-40 Reanalysis Dataset, applying the Objective Synoptic Analysis Technique(OSAT), tropical cyclone track similarity area index(TSAI) and the dynamic composite analysis, analyses were carried out on characteristics of TC extreme precipitation and its preliminary causes from a perspective of TC daily precipitation(TCP) and TC maximum daily precipitation(TMP). Results are as follows:1)During the past 50 years, regional-mean frequencies of TMPs above 50mm,150mm,250mm and 350mm show not obvious and weak decreasing trends and weak and weak increasing trends with obvious interannual variations, respectively. regional-mean frequencies of TMPs above 50mm,100mm and 250mm show weak and weak decreasing trends and weak increasing trend with obvious interannual variations, respectively. The trends above are not obvious.2)Frequencies and intensities of different level TCPs and TMPs present a similar distribution pattern of large values distributing mainly along the coastal regions with decreasing quickly from coastal regions to inland regions. In addition, the large values concentrate in three subregions:the eastern coast of Guangdong(the eastern subregion),the western coast of the Pearl River Delta(the middle subregion) and the coast from the Leizhou Peninsula to coast of Guangxi(the western subregion), with the western subregion being the one with largest values of intensity and frequency.3)Comparison analysis reveals that, the TCs, which cause extreme precipitation in the western subregion, have tracks of the strongest regularity with mainly westward movement and landfall locations concentrating within the area. Meanwhile, causes analysis preliminarily reveals that TC’s slow movement and reinforcement of the South China Sea Summer Monsoon are in favor of producing extreme precipitation in the western subregion.4) Numerical experiment captures the westward track and intensity of TC KAI-TAK, and the associated rainfall pattern. Sensitivity experiment suggests that monsoonal flows are weakened in the South China Sea. Meanwhile, TC intensity is weakened, rain is reduced among the TC range as a whole, rain band moves south, So it proves ture that weakened South China Sea Summer Monsoon is not in favor of producing extreme precipitation in the western subregion as mentioned before.