Dependence of sea surface emissivity on temperature‐dependent refractive index

Abstract

AbstractTheoretical calculations of emissivity difference, Δε, with changing of water temperature from 301 to 279 K are performed at 820 cm−1 using the temperature‐dependent refractive index of sea water recently proposed by Newman and co‐workers. The results are compared with the calculations using the temperature‐dependent refractive index presented in 1977 by Pinkley and co‐workers. The difference in Δε between the two models is as small as ∼0.0003 for emission angles less than 30° . At larger emission angles, the discrepancy in Δε between the two models is notable. For example, Δε are ∼ − 0.0055 and ∼ − 0.0070 for the Newman and Pinkley models, respectively, at an emission angle of 55° . This discrepancy is mainly caused by the fact that the temperature dependence of the imaginary part of the refractive index of the Pinkley model is ∼1.5 times larger than that of the Newman model and the sea surface emissivity is significantly sensitive to the change of imaginary refractive index at this wavenumber. It is important that accurate values of the imaginary part of the refractive index be obtained. Copyright © 2008 Royal Meteorological Society