D. Data processing and scientific use
Data processing and scientific use are also a main subject of cooperation between France and India. India, being responsible of the satellite, is also responsible of the ground receiving station and of the operational processing level 1, which means the transformation of the raw data received from the satellite into “calibrated, geolocated radiance data”. This level 1 processing depends obviously on the characteristics of the satellite and the instruments, including their calibration. For ScaRaB and SAPHIR, which are totally French instruments, level 1 algorithms are worked on by French teams, then transferred to Indian partners. For Madras, work has to be splitted between the two partners.
The second level of processing consists in the transformation of “Level 1 data” into geophysical parameters, as radiative fluxes, water vapour amounts, precipitation intensities. This is called “Level 2” processing. It is performed separatly in France and India, using specific methods in each country. Methods based on physical “inversion of radiances”, statistical methods and methods based on assimilation of data in models are considered.
Another specificity of Megha-Tropiques is synergistic processing of the three instruments, or of MT instruments and geostationary data, which provide a very good space time coverage of the tropics, specially useful in complement of MT for the cloud cover properties and evolution. Other combinations of instruments is possible for example with the microwave radiometers satellites (AMSR-E, SSMI/S, TMI, SSMi).
Finally, scientific studies on the tropical meteorological and climatic processes, which constitute the final aim of MT will be performed in the interested teams of both countries, but also in all countries interested in the World.
In order to prepare all these scientific activities, the establishment of relevant data bases containing data from existing satellites is necessary. In India, ISRO is setting up a system called MOSDAC in Ahmedabad, whereas in France, a MT preparation data base is set up in the frame of the data processing center ICARE (CNES-CNRS center in Lille and Paris), which is also in charge of level 2 and 3 processing for France.