Although SMOS was launched in November 2009, the sea surface salinity maps retrieved from SMOS brightness temperature images have not yet achieved the mission requirements. Strong spatio-temporal biases prevent consistent analysis of global datasets acquired at several week intervals. Characterization and mitigation of instrumental and model biases are of primary importance.
The systematic error correction strategy implemented in the SMOS operational processing chain mixes all kind of biases, namely related to the antenna patterns, the antenna losses, the foreign source imperfect corrections, or the errors in the forward model used for geophysical parameter inversion.
This practical strategy prevents consistent calibration error diagnostic or forward model improvement tasks. An alternative strategy which separates the different systematic error contributions and provides higher stability of the estimates is required and has recently been proposed. It allows diagnosis of the systematic (constant with time) TB errors in the antenna frame, with no impact of forward model errors.
Since March 5th 2013, SMOS-BEC distributes new level 3 and level 4 products derived from level 2 data processed by ESA
The SMOS data used to compute the new level 3 and level 4 Ocean products come from level 2 (L2) Ocean Salinity User Data Product (UDP) and Ocean Salinity Data Analysis Product (DAP). These UDP and DAP files are generated by ESA and include geophysical parameters, a theoretical estimate of their accuracy, and flags and descriptors for the product quality for three different roughness models. These new products developed by BEC are based on the roughness model described in Guimbard et al IEEETrans. Geeosci. Remote Sens. (2012).
The new maps have been created using an improved filtering technique over L2 products. Also the resolution has been modified: current maps are generated at 0.25 degree resolution (rather than 1 degree resolution as for the previous products). The variety of averaging periods has also been increased: three days, nine days (generated every three days), monthly, seasonal, and annual averages (see SMOS-BEC Ocean and Land Products Description for additional information) are now available.
This is the first post in the new CP34 BEC blog.
The SMOS Barcelona Expert Center (BEC) is an ESA Expert Support Laboratory for the Soil Moisture and Ocean Salinity (SMOS) mission, an innovative Earth Observation satellite devoted to the remote sensing of soil moisture over land and sea surface salinity over the oceans. This is the first time that both variables are measured by a single spaceborne instrument.
The SMOS single payload consists of the Microwave Imaging Radiometer using Aperture Synthesis (MIRAS), a L-band interferometric radiometer. This new instrument allows taking the maximum profit from the capabilities of L-band to infer the geophysical variables of interest, but it is also a very challenging device, requiring sophisticated calibration, correction, pre- and post-processing algorithms. As an ESA ESL, the main commitment of BEC is to develop and test new algorithms to improve the quality of SMOS Level 2 products. However, the goal of BEC is also to generate higher added-value products of interest for a broad range of users. This led to the creation of CP34 as a dedicated production center for SMOS Level 3 and Level 4 products a few years ago. Since the beginning of the mission, CP34 has provided L3 products for sea surface salinity and soil moisture in an operational way.