ATMOSPHERIC PARAMETERS OVER THE MARGINAL ICE ZONE RETREIVAL FROM ANSR/AMSR-E DATA

Abstract

A direct radiative transfer model, 478 radiosondes complimented by the cloud liquid water content profiles and the underlying surface temperatures and emissivities were used to simulate the brightness temperatures T Bs over the Marginal Ice Zone at ADEOS-II AMSR and Aqua AMSR-E frequencies. The precipitable water V varied from 0.63 to 18.5kg/m², the total cloud liquid water content Q<=0.25kg/m² and SST£1°C. The mean experimental values of emissivity and its fluctuations for several types of the first-year ice at ice temperature of 263 to 271K were used in a model. The sea surface emissivity was computed taking into account wind action. 10 values of ice concentration C uniformly distributed from 0.0 to 1.0 were selected for each radiosonde. The radiometer noises of 0.5K were added to the modeled T Bs. Standard regression techniques were applied to retrieve V, Q and C from the simulated T Bs with vertical and horizontal polarization at 18.7, 23.8 and 36.5GHz. The retrieval errors increase from »0.5 to »1.7kg/m² for V and from »0.02 to »0.06 kg/m² for Q with the increase of C from 0.0-0.3 to 0.7-1.0. The algorithms were used to retrieve V, Q and C in the Okhotsk Sea from the T Bs measured by AMSR-E