Application Research Of East Asian Regional Reanalysis To Tropical Cyclone Simulation In The Northwest Pacific

This Paper mainly discusses the application of high-resolution East Asian regional reanalysis in the tropical cyclone simulation of the Northwest Pacific in 2015,mainly studying the track and intensity of tropical cyclones and the accompanying precipitation when landing in South China.The East Asian regional reanalysis system was developed by using the Advanced Research Weather Research and Forecasting Model(WRF-ARW)mesoscale model and the Gridpoint Statistical Interpolation(GSI)assimilation system.This paper is based on the preliminary results of high-resolution East Asian regional reanalysis from the East Asian Regional Reanalysis System(hereinafter referred to as EARS),based on the simulation results of the tropical cyclone's track and intensity in 2015 in the Northwest Pacific and the precipitation forecast of tropical cyclones landing in South China is the research object,compared with National Centers for Environmental Prediction reanalysis(NCEP),the European Centre for Medium-Range Weather Forecasts reanalysis(ERA-Interim),the new generation reanalysis of European Centre for Medium-Range Weather Forecasts(ERA5)and Japan Meteorological Agency(JMA)55-year(JRA55)reanalysis in the global world,and compared with the observation of the best track database of China Meteorological Administration(CMA),and obtains the following results and conclusions:(1)The average distance error of the 22 tropical cyclone centers between the EARS,NCEP,ERA-Interim,ERA5,JRA55 and the CMA best track database respectively is 20?140km,indicating that the EARS and the other four reanalysis datasets can accurately reproduce the tropical cyclone track.The tropical cyclone tracks reproduced by ERA5 is the best,followed by JRA55,EARS and ERA-Interim,and the worst is NCEP.When East Asian regional reanalysis system used ERA5 as the initial field and boundary,the simulation of the tropical cyclone “Mujigae” track was basically consistent with ERA5,and the simulated track is more accurate.The direction error of tropical cyclone motion simulated by EARS is large in the development and extinction phases.East Asian regional reanalysis system used ERA5 as the initial field and boundary can improve the direction error of the tropical cyclone“Mujigae” motion.(2)East Asian regional reanalysis has higher spatial and temporal resolution and a reasonable data assimilation scheme.It can assimilate more accurate regional observations.It has a better ability to simulate the maximum wind speed near the center of tropical cyclone,slightly better than ERA5,and significantly more accurate than JRA55,ERA-Interim,NCEP.It can better reflect the intensity of tropical cyclones and obtain the refined structure of tropical cyclones.(3)From the Threat Score(TS)of East Asian regional reanalysis system used ERA5 as the initial field and boundary(hereinafter referred to as: EARS(ERA5))and used ERA-Interim as the initial field and boundary(hereinafter referred to as: EARS(ERA-Interim)and merged precipitation respectively,different dates,different initial fields,boundary and different precipitation thresholds will produce different predictions for East Asian regional reanalysis system's precipitation forecast for tropical cyclones in South China influences.Overall,EARS(ERA5)is more accurate than EARS(ERA-Interim)in precipitation forecasting of tropical cyclones in South China.Combining the intensity and landing time of tropical cyclones,EARS(ERA5)is more accurate than EARS(ERA-Interim)in precipitation forecasting of tropical cyclones in South China during landing.(4)Through comparative analysis with the new generation of land surface reanalysis(ERA5-Land)of the European Medium-Term Weather Forecast Center,the results are as follows: different precipitation thresholds and different dates will affect EARS(ERA5)and ERA5-Land forecast of tropical cyclone's precipitation in South China.EARS(ERA5)is more accurate in forecasting precipitation in South China during tropical cyclone "Kujira,Linfa",ERA5-Land is more accurate in forecasting precipitation in South China during tropical cyclone "Mujigae".Regardless of whether it is EARS(ERA5)or ERA5-Land,and the precipitation forecast of the tropical cyclone in South China at the mature stage is more accurate.