Evaluation of seawater permittivity models at 150 GHz using satellite observations

Multisensor satellite measurements from the special sensor microwave water vapor sounder (SSM/T-2), special sensor microwave imager (SSM/I), and opera tional linescan system (OLS) are used to retrieve sea surface emissivity at 150 GHz with the goal of assessing selected permittivity models, Retrieval s mere limited to clear-sky SSM/T-2 field-of-views under arctic winter cond itions to minimize atmospheric attenuation. Results show there is sometimes wide disagreement between the models and the observations even when consid ering measurement and model errors with differences as high as 2.4% (or equ ivalently approximate to 5 K). Models consisting of two relaxation time con stants rather than one are found to be in closer agreement with the observa tions. The largest permittivity model errors have substantial effects on ph ysically based atmospheric parameter retrievals with systematic errors of - 65% and -20% for a column mater vapor amount of 2 kg m(-2) and cloud liquid mater path of 0.1 kg m(-2), respectively.