A roughness correction algorithm for aquarius using MWR

Aquarius/SAC-D is a collaborative earth science satellite mission, between NASA and the Argentine Space Agency, CONAE. The two microwave radiometers on the satellite are the NASA Aquarius (AQ, L-band 1.4 GHz) and the CONAE MicroWave Radiometer (MWR, Ka-band 36.5 GHz V-& H-pol and K-band 23.8 GHz H-pol). The mission science objective is to provide high-resolution global sea surface salinity (SSS) maps every 7-days, which are derived using the AQ combined L-band radiometer/scatterometer. The application of L-band radiometry to measure SSS is a difficult task, and there are many corrections that must be made correctly to obtain accurate SSS data. One of the major error sources is the effect of ocean roughness that “warms” the ocean brightness temperature (Tb) by 0.28 K. In this paper, an alternative sea surface roughness correction algorithm is presented that uses a new semi-empirical Radiative Transfer Model (RTM) to estimate the ocean emissivity. This RTM has been tuned using 1-years of observed AQ and MWR Tb´s and corresponding atmospheric and oceanic environmental conditions from numerical weather and oceanographic models. Results of independent comparisons (not used in the RTM tuning process) will be presented between the AQ scatterometer derived ocean roughness correction and the MWR roughness correction algorithm. Also, SSS retrievals using these two independent approaches will be compared to an oceanographic salinity model, known as Hybrid Coordinate Ocean Model (HYCOM) salinity.