Baseline configuration of a MM-wave temperature sounding unit of ISRO

This paper presents the proposed configuration of a temperature sounding unit to be flown along with a Ku band pencil beam Scatterometer in a Low-Earth-Orbit (LEO) polar sun-synchronous orbit. This will be the first millimeter-wave atmospheric sounder of the Indian Space Research Organization (ISRO). This configuration has been arrived at with the restrictions on mass and volume for the payload, for accommodation in IMS(Indian Mini Satellite). The selection of the frequency channels are guided by temperature resolution desired, and the channel-bandwidth which is critical for getting desired temperature sensitivity. The aim is to sound upto 40km in the atmosphere with about 4 km vertical resolution. The overall receiver noise figure for the channels in the 5mm band (50-60GHz) has been kept at 5dB as is compliant with the receiver simulation figures. The overall configuration has been worked out taking into consideration the geometric as well radiometric performances desired by such a system. The design goals are assumed to be similar to that available from the operational AMSU-A unit of NOAA.