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MADRAS (Microwave Analysis and Detection of Rain and Atmospheric Systems) is a 9-channel self-calibrating microwave imager. It is the main instrument of the MEGHA-TROPIQUES mission, jointly managed by the CNES and ISRO agencies. MADRAS is a conical scanning radiometer with a 56° incidence angle, close from the SSM/I and TMI concepts. MADRAS has operating frequencies in the range of 18.7GHz to 157GHz. The 157 GHz is 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. Moreover, the Megha-Tropiques microwave radiometer MADRAS could be one element complementing the constellation of mini-satellites of the Global Precipitation Mission. The table below gives the main mission objective for each channel.

Main Characteristics of the MADRAS Channels

Channel Number Frequency (Ghz)±(Mhz) Polarization NEΔ @ 300K
required, (goal)
Pixel Size Main Use
1 18.7 ± 100 V 0.7 K (0.5) 40 km ocean rain and surface wind
2 18.7 ± 100 H 0.7 K (0.5) 40 km ocean rain and surface wind
3 23.8 ± 200 V 0.7 K (0.5) 40 km integrated water vapor
4 36.5 ± 500 V 0.7 K (0.5) 40 km cloud liquid water
5 36.5 ± 500 H 0.7 K (0.5) 40 km cloud liquid water
6 89 ± 1350 V 1.1 K (1.0) 10 km convective rain areas
7 89 ± 1350 H 1.1 K (1.0) 10 km convective rain areas
8 157 ± 1350 V 2.2 K (2.0) 6 km cloud top ice
9 157 ± 1350 H 2.2 K (2.0) 6 km cloud top ice

The main uses given here are only indicative, most of the products being extracted from algorithms combining the different channels information. The resolutions are those expected in the different channels, accounting for the specification of 10 km given for the 89 GHz channel.

V: Polarization vector is parallel to scan plane at nadir
H: Polarization vector is perpendicular to scan plane at nadir

Source: ISRO-CNES Megha-Tropiques Web Site