Retrieval of the Ocean Skin Temperature Profiles From Measurements of Infrared Hyperspectral Radiometers—Part II: Field Data Analysis

Abstract

To obtain the vertical temperature profile of the thermal skin layer on the aqueous side of the ocean–atmosphere interface from radiance measurements of hyperspectral infrared radiometers, regularization methods are used to address the nonlinearity and ill-conditioning of the inverse problem associated with the retrieval. This paper demonstrates the truncated singular value decomposition regularization technique on field data sets obtained from the Marine-Atmospheric Emitted Radiance Interferometer (M-AERI). The M-AERI takes highly accurate and spectrally resolved radiance measurements in the infrared, which allows for the sensing of temperature values within thermal skin layer depths of less than 1 mm below the ocean surface. Results showed temperature inversions found in the solution, but these are deemed unphysical, based on previous tests on synthetic data and by a scaling analysis using the Rayleigh number, which are presented here. The importance of sea surface emissivity for performing the atmospheric correction to M-AERI measurements to derive surface emissivity spectra is also discussed. The retrieved profiles exhibit a smooth exponential-like structure that agrees well with theory.