Research On The Charateristic Of Precipitation Related To Tropical Cyclones Landing In Mainland China During Different ENSO Phases

Based on Objective Synoptic Analysis Technique,using the best-track dataset from CMA-STI and precipitation dataset provided by CMA,rainfall caused by tropical cyclone landing in mainland China(called TC rainfall or TC precipitation)during JAS in 1981-2017was seperated.In this paper,after setting up a TC rainfall impact factor decomposition method,the climatic characteristics of TC rainfall and its influencing factors were researched in the first part.After using ERSSTv5 from NOAA to classify ENSO into four phases and defining an anomal genetic diagnosis method,the charateristic and the possible reason of TC rainfall during different ENSO phases(EPW,CPW,EPC and CPC)were analyzed.In the final part,as an example,the possible influence mechanism of EPW on rainfall variation over southern China related to TC was shown using ERA5 monthly and NCEP daily reanalysis dataset.The main conclusions are as follows:1)TC rainfall focus on JAS,and delivered about 156 km~3 precipitation to China each year during JAS,which contributes significantly to the total precipitation.South China is a sensitive region for TC precipitation.2)The TC anomalous precipitation in different phases of ENSO showed an asymmetric characteristic.The main influencing factor in the two warm phases(EPW and CPW)was TC influence frequency,while it was duration time of TC in the cold phase(EPC and CPC).The causes of TC precipitation anomalies were complex.Under the common influence of multiple complex factors,TC precipitation anomalies are not significant during most phases.3)The anomalous SST warming in the eastern equatorial Pacific Ocean leads to the response of the atmospheric circulation over the northwest Pacific Ocean,which may play causes the changes in the environment for the generation of TC,the guiding airflow,the precipitation conditions,and the horizontal shear of zonal wind,which may give rise to the significant abnormal reduction in TC rainfall in southern China mainland.Among them,TC influence frequency is the main direct influence factor,while TC path anomaly is the main indirect influence factor.