Impact of Sun glint on the SMOS Retrieved Brightness Temperature Maps for Almost Four Years of Data

Abstract

Abstract The European Space Agency's Soil Moisture and Ocean Salinity (SMOS) satellite was launched on November 2nd, 2009. The purpose of this mission is to retrieve global maps of soil moisture and ocean surface salinity. The single payload on board the SMOS satellite is a two-dimensional L-band interferometer, the Microwave Imaging Radiometer with Aperture Synthesis (MIRAS). This instrument measures the cross-correlations of the signals between many pairs of receivers distributed in a Y-shaped array. After de-normalization and image reconstruction, these cross-correlations yield brightness temperature images whose usable portion extends over a swath nearly 1000 km across. Geophysical retrieval algorithms are applied to these images to yield soil moisture (SM) over land and sea surface salinity (SSS) over the ocean. This paper examines the impact of sun glint on these images, focusing on the open ocean, where sun glint is shown to have a major impact on the images in descending passes from December through January. The consistency between the sun glint present in the data and that predicted by the model developed prior to launch is assessed in terms of both spatial variation across the swath and temporal variation from June 2010 to February 2014.