The major scientific objective of the Megha-Tropiques (MT) satellite, an Indian Space Research Organisation (ISRO)-Centre National d'Études Spatiales (CNES) collaborative project, is to understand the energy and water cycles in the global tropical region. With its 20 • inclined orbit, it will frequently measure radiation emitted by the Earth-Atmosphere System in the visible, infrared and microwave spectrum through its four sensors on board. Various geophysical parameters, namely water vapour, cloud liquid water and surface winds over oceanic regions, and the rainfall, humidity profile and top-of-atmosphere radiative fluxes over land as well as over oceanic regions will be derived from the measurements made by these instruments. This article deals with the efforts made by ISRO to develop algorithms for deriving these geophysical parameters from the microwave imager and sounder, mentioning the pre-launch specifications with prelude examples from existing space-borne sensors of similar types. The sensor-specific algorithms are presented in different sections.

This letter deals with the development of geophysical model functions (GMFs) specific to Oceansat-2 Scatterometer (OSCAT) for the operational retrieval of global ocean surface vector winds from OSCAT. It makes use of OSCAT-measured radar backscatter and the surface analysis winds at 10-m neutral-stability height from the European Centre for MediumRange Weather Forecasts (ECMWF) model for the period from November 2009 to April 2010. The OSCAT-specific GMF has been used for retrieving the vector solutions from backscatter data as well as for the directional ambiguity removal. The procedures and the conditions incorporated for the same are presented in this letter.Index Terms-Geophysical model function, Oceansat-2, ocean surface wind vector, scatterometer.