Status of sea surface salinity product provided by SMOS

Font, Jordi ... et al.-- 1st SMOS Science Workshop, 27-29 September 2011, Arles, France.-- 4 pages, 2 figures
The SMOS (Soil Moisture and Ocean Salinity) objectives for sea surface salinity (SSS) are to provide global coverage with repetition rate and accuracy adequate for oceanographic, climatological and hydrological studies and increase the present knowledge on: Large-scale ocean circulation, Water cycle exchange rates quantitative estimation, Occurrence of natural catastrophic events, Management of water resources, Role of the ocean in the climate system. To this end the mission requirements were set to determine SSS values with an accuracy of 0.1, in boxes of 100-200 km and temporal averages of 10-30 days [1]. Even the SMOS frequency, 1413 MHz within the microwave L-band, is close to the maximum sensitivity of brightness temperature (TB) to salinity variations, this sensitivity is much smaller than the one for soil moisture. The total range of ocean SSS spans a TB range of 5K, while for soil moisture is 100 K. This implies that the SSS retrieval by SMOS requires a higher performance of the MIRAS interferometric radiometer, the single payload on board [2]. The ESA SMOS Ocean Salinity Level 2 Processor (L2OS) has been designed from 2004 by the team that co-authors this manuscript, and is being now improved to increase its performance and solve the deficiencies observed since it entered into operation during the SMOS Commissioning Phase. It relies on a minimisation of the comparison between the TB at different incidence angles measured by SMOS when overflying a single ocean spot, and a modeling of the sea surface L-band emission that takes into account the actual environmental conditions and all the processes that impact or modify this emission [3]. In this paper we present the status of the L2 ocean products as they were operationally generated during the SMOS Science Workshop in September 2011, the improvements expected from the new processors (version 500) in operation by mid October 2011 and to be used also for the 2011 general reprocessing, and the issues on SMOS SSS retrieval still being investigated at that moment