Megha-Tropiques is a satellite mission to study the water cycle in the tropical atmosphere in the context of climate change A collaborative effort between Indian Space Research Organisation and French Centre National d’Etudes Spatiales, Megha-Tropiques was successfully deployed into orbit by a PSLV rocket in October 2011. Megha-Tropiques was initially scrapped in 2003, but later revived in 2004 after India increased its contribution and overall costs were lowered. With the progress made by GEWEX, Megha-Tropiques is designed to understand tropical meteorological and climatic processes, by obtaining reliable statistics on the water and energy budget of the tropical atmosphere. Megha-Tropiques complements other data in the current regional monsoon projects such as MAHASRI and the completed GAME project. Megha-Tropiques also seeks to describe the evolution of major tropical weather systems. The focus will be the repetitive measurement of the tropics.
Design
Megha-Tropiques provides instruments that allow simultaneously observation of 3 interrelated components of the atmospheric engine: water vapor, condensed water, and radiative fluxes, facilitating the repetitive sampling of the inter-tropical zone over long periods of time. Its microwave radiometer, Multi-frequency Microwave Scanning Radiometer, complements the radiometers of the other elements of the Global Precipitation Measurement mission.
Payload
Instruments fulfill a role to other on geostationary satellites. In this, microwave instruments are essential.
Microwave Analysis and Detection of Rain and Atmospheric Structures is a microwave imager, with conical scanning, close from the SSM/I and TMI concepts. The main aim of the mission being the study of cloud systems, a frequency has been added in order to study the high level ice clouds associated with the convective systems, and to serve as a window channel relative to the sounding instrument at 183 GHz.
Sounder for Probing Vertical Profiles of Humidity is a sounding instrument with 6 channels near the absorption band of water vapor at 183 GHz. These channels provide relatively narrow weighting functions from the surface to about 10 km, allowing retrieving water vapor profiles in the cloud free troposphere. The scanning is cross-track, up to an incidence angle of 50°. The resolution at nadir is of 10 km.
Scanner for Radiation Budget is a scanning radiative budget instrument, which has already been launched twice on Russian satellites. The basic measurements of ScaRaB are the radiances in two wide channels, a solar channel, and a total channel, allowing to derive longwave radiances. The resolution at nadir will be 40 km from an orbit at 870 km. The procedures of calibration and processing of the data in order to derive fluxes from the original radiances have been set up and tested by CNES and LMD.
Radio Occultation Sensor for Vertical Profiling of Temperature and Humidity procured from Italy for vertical profiling of temperature and humidity.
