MEDSPIRATION : A European Contribution to the Global Ocean Data Assimilation Experiment High Resolution Sea Surface Temperature Pilot Project (GODAE/GHRSST)
Jean-Francois Piolle(1) , Ian Robinson(2)
, and Pierre Leborgne(3)
(2) NOC, European way, SO14 3ZH Southampton, France
(3) METEO-FRANCE, Centre de Meteorologie Spatiale, 22302 Lannion, France
There are presently several independent representations of SST being produced from different satellite systems by a number of agencies. Discrepancies between them can confuse the assimilation process into the model. Individually none of them is as good as the models require. GODAE has identified that numerical ocean forecasting models need a near-real time supply of SST data, sampled often enough to resolve the diurnal cycle, with an accuracy better than 0.2 K, and a spatial resolution better than 10 km. To achieve this combination of temporal, spatial and radiometric resolution is possible only by combining the best capabilities of different types of sensors. Satellite oceanographers have responded to this challenge to produce new SST products drawing on the best characteristics of several different systems, by setting up GHRSST-PP. This project aims to combine all the available SST data from across the globe to form a high resolution, high accuracy and high avail
ability SST product for the new century.
GHRSST-PP is organised as a partnership between regional groups responsible for generating SST products, to a common GHRSST specification, within a limited geographical area. Several such regional data assembly centres (RDACs) are envisaged. Their primary task is to collate all level 2 satellite SST measurements within their region, perform quality assessment and reissue the data in a common format, including a measure of the quality of every measurement, suitable for model assimilation. These are called GHRSST L2P data. They also pair in situ measurements of SST with corresponding satellite data to produce a match-up database (GHRSST MDB).
The Medspiration Project is a European initiative funded by ESA to serve as a European RDAC for GHRSST-PP, generating operationnally in near real-time L2P, including ENVISAT/AATSR, and MDB products for the Atlantic Ocean and its adjoining seas. The coverage of AATSR L2P products will be extended to global ocean starting from September 2005. It also assembles diagnostic datasets (GHRSST HR-DDS) in which all available L2P and L4 data for a number of select small areas are assembled together and resampled onto a common grid to assist intercomparison and characterisation of the different input data sources. Additionally Medspiration has the task of producing for general use an ultra-high resolution (2km) analysed SST product for the Mediterranean Sea, merging the best SST data from all available sensors.
Medspiration is a joined project between IFREMER, METEO-FRANCE and SOC. It is now the reference data center for SST in Europe. In the frame of MERSEA project, it will be a basis for a European GDAC, collecting L2P products from all RDACs and producing a global analysed SST products using well defined procedures to harmonise the discrepancies between SSTs from different types of sensor, and to fill sampling gaps.