This month’s newsletter is devoted to the latest space mission and their use in physical oceasnography. A focus is here put on the possible physical oceanography applications of the SMOS, GOCE and CRYOSAT missions.
SMOS (Soil Moisture and Ocean Salinity), launched on November 2, 2009, is the first satellite mission addressing sea surface salinity measurements from space. Realistic salinity maps have been obtained and preliminary validation tests against in situ data indicate that the SMOS team is approaching its goals. SMOS will be a milestone in the route for incorporating salinity to operational remote sensing.
The GOCE (Gravity Field and Steady-State Ocean Circulation) satellite, first core Earth Explorer mission from ESA’s Living Planet programme, was successfully launched on March, 17th 2009. One primary objective of the GOCE mission is to determine the Earth geoid with an accuracy of 1-2 cm for a spatial resolution of 100 km. This is an important supplementary step towards the better estimation of the ocean Mean Dynamic Topography, a key reference surface for the assimilation of altimetric Sea Level Anomalies into operational ocean forecasting systems.
ESA’s CRYOSAT Earth Explorer mission was launched on 8 April 2010. Although its first mission is to provide the first satellite maps of sea-ice thickness, the CRYOSAT mission is also operating over ocean surfaces providing a new source of valuable altimeter measurements. It represents an additional altimeter ocean mission complementary to existing Envisat, Jason-1 and Jason-2 missions in the operational multimission processing chain of the SSALTO/DUACS system used in MyOcean.
The newsletter is presenting the following scientific articles: First, Font et al. present the characteristics of the SMOS instrument, a summary of the sea surface salinity retrieval from SMOS observations and shows initial results obtained one year and a half after launch. At present there are still several issues being addressed by the SMOS team, mainly related to low level data processing but also to the retrieval of salinity from radiometric measurements, which prevent by now from reaching the mission objectives in terms of salinity accuracy. However, realistic salinity maps have been obtained and will be presented. Second, Rio and Mulet carry out an independent validation of the different GOCE geoid models, in order to assess their accuracy and determine which one is better suited for oceanographic applications and Mean Dynamic Topography estimation. Both the impact of the different methodologies used to compute the gravity fields as well as the contribution of the four months of supplementary data have been checked. Third, Dorendeu et al. present a dedicated experiment in order to estimate to which extent valuable ocean altimetric signals can be extracted from CRYOSAT data and how this opportunity mission could be merged with existing Envisat, Jason-1 and Jason-2 missions in the operational multimission processing chain of the SSALTO/DUACS system. Finally, Meinvielle et al. are writing on how to optimally improve the atmospheric forcing of long term global Ocean simulations with Sea Surface Temperature (SST) observations. The objective of their research is to develop a new assimilation scheme based on advanced statistical methods that will use SST satellite observations to constrain the surface forcing function of long term ocean circulation simulations.
The next October 2011 issue will be dedicated to the reanalysis and reprocessing products within MyOcean. We wish you a pleasant reading!