3DVar Assimilation Of GPS Occultation Refractivity Data And Its Impact On Typhoon Forecast

Disasters brought by typhoon are usually in the before and after landing, due to past sea exploration technology and the limited observational data, landed the question research to the typhoon to be limited. In recent years, along with the air sounding technology development, GPS occultation refractivity data(GPSRF) series of high spatial and temporal resolution of the unconventional information makes up for the shortage of ocean observational data, using the assimilation way, application of unconventional data in model may be effective in improving the model initial fields.In this study, the Weather Research and Forecasting(WRF) Model with three-dimensional data assimilation (3DVAR) is utilized to investigate influences of GPSRF data taken from COSMIC and CHAMP satellites on simulations of typhoon "Setpa". On this basis, the track, density, and precipitation of "Setpa" are analysed with GPSRF data in the application. The results indicated the GPSRF data have benefit in terms of the water vapor. GPSRF data assimilation showed the positive impact on precipitation rather than track and density forecast. Assimilation with the 12h-cycling experiment gave better track forecast than the cold-start runs because more observation information was ingested into the initial condition.Although GPSRF data can provide useful information on the thermodynamic variables, they lack the ability to measure wind. So, cloud drift wind data taken from FY-2C satellite were ingested into the model. The result displays the further improved in the density and wind field of "Setpa", but with track and precipitation less infected.