Analysis of Deriving Stratospheric Atmospheric Winds from COSMIC Radio Occultation Data

Three different calculation methods are constructed with the newly launched COSMIC/ FORMOSAT-3 system.The analysis is based on the radio occultation data sample collected the observation during Jan.,Apr.,July and Oct.2007.For the validation,the data is compared with monthly average wind data of ECMWF's ERA-interim data sets.The comparisons are done in terms of mean winds profiles for various latitudes,longitudinal-latitudinal winds variations for particular pressure level and latitude-height distributions of zonal mean winds for different seasons,and reveal excellent resemblance between the COSMIC measurements and the model outputs in stratosphere.The bias is larger in upper stratosphere than in lower stratosphere,however,the error is less than 10 m/s below 1 hPa.The differences of the three calculated winds field are very small,the winds field derived from refractive index and temperature data is nearly the same,the bias of winds derived from height is relatively larger,but the differences of error is less than 2 m/s than the two fields infered before.