SCATSAT-1 – Satellite for Weather Forecasting, Cyclone Detection and Tracking
Global wind data, which is very crucial for cyclone detection and weather forecasting applications, was gathered by Scatterometer instrument flown as one of the payloads in OCEANSAT- 2 satellite. This data was utilised by national and international users and proved to be a very important tool for oceanographic studies. SCATSAT-1 is the continuity mission for Scatterometer payload carried by the earlier Oceansat-2 satellite.
The magnitude and direction of the wind vector at the ocean surface is a key parameter for weather prediction as well as detection and tracking of cyclones. The objectives of SCATSAT-1 are to facilitate the weather forecasting services to the user communities through the generation of wind vector products. The Ku-band Scatterometer payload carried by SCATSAT-1 has enhanced features compared to the similar one carried by Oceansat-2 launched in 2009.
SCATSAT-1 is built around ISRO’s small satellite ‘IMS-2 BUS’ and the mass of the spacecraft is 371 kilograms. The spacecraft will work in sun synchronous orbit of 720 km. altitude with an inclination of 98.1 deg. This will be a polar orbiting satellite and will take two days to cover the entire globe. The expected life span of the satellite is 5 years with non-stop 24 X 7 all weather operations. Wind speed is measured in the range of 3m/s to 30m/s and 0-360 deg directions. Finally wind vector grids of 25kms*25kms over oceans will be generated for the entire globe.
The satellite is carrying a Ku-band Scanning Scatterometer radar instrument operating at 13.515 GHz similar to the instrument flown onboard Oceansat-2. The payload instrument will be a vital tool globally used to study wind patterns above the ocean, air-sea interactions, ocean circulation and their overall effects on weather patterns. Climate quality data is expected to be obtained from this spacecraft to provide accurate knowledge regarding Himalayan ice formation and melting, cyclones formation near Indian coastal line, Greenland ice melting, etc.,
Scatterometer operates on the principle of radar. When the radar radiates energy pulses towards the ocean’s surface, a backscatter effect is produced due to interaction between electromagnetic waves and sea surface waves, which is function of speed and direction of surface winds over the oceans.
This process of receiving back-scattered signal is carried out while conically scanning or rotating the antenna along with the motion of the satellite giving a swath of 1400 km. The collected data is processed onboard to generate estimate of backscattered power/signals and stored on a data recorder. This recorded data is then transmitted to ground station which is converted into wind vectors for the global user.
These wind vectors will help meteorologists in accurately predict the cyclone formation, its movement and estimated landfall. It may be recalled that Ocean wind vectors data helped in accurately predicting cyclone ‘Phailin’ in the Odisha coast in 2013, which helped in mitigation and saving of mankind and livestock.
SCATSAT-1 is a global mission and data generated from the Scatterometer, developed by ISRO will also be utilised by the American space agency NASA and European Space Agency organisation, EUMETSAT to provide global weather data to all those involved in weather studies and global climate change studies.