Uncertainties in the permittivity model for seawater in FASTEM and implications for the calibration/validation of microwave imagers

摘要

This paper evaluates uncertainties in the ocean permittivity model needed to compute surface emission and reflection, at frequencies of 6 - 90 GHz. The study transforms permittivities and laboratory measurement uncertainties into typical brightness temperatures for microwave imagers. It is established that the permittivity model used by FASTEM agrees with the laboratory measurements to within their published uncertainties at frequencies of 23 GHz, 37 GHz and 89 GHz, but this is not the case at 6.8, 10.65 and 18.7 GHz, particularly at low temperatures.