How Isro satellites tracked Fani

As meteorologists observed a trough of low in the southern Indian Ocean more than a week ago, five Indian satellites kept a constant eye on the system as it brewed into Fani.

As it developed into an “extremely severe cyclone”, the satellites launched by Isro sent data every 15 minutes to the ground station, helping track and forecast its movement, saving hundreds of lives in the process.

According to IMD, data from satellites Insat-3D, Insat-3DR, Scatsat-1, Oceansat-2 and Megha Tropiques was used to study the intensity, location and cloud cover around Fani. There was a cloud cover around the eye of the storm up to 1,000 km radius, though the rain clouds were only up to a radius of 100 to 200 km. The rest were at a height of around 10,000 feet.

With IMD able to accurately forecast the exact location where the cyclone was to make landfall, officials in Odisha, Andhra Pradesh and West Bengal were able to evacuate more than 11.5 lakh people to safety.

One of the main payloads from the satellites used to mark the eye of Fani was the scatterometer onboard Scatsat-1, a polar orbiting miniature satellite, and Oceansat-2, sending data about ocean surface, wind speed and wind direction.

Images from both Insat-3D and Insat-3DR helped meteorologists measure the temperature and moisture levels at different heights, humidity, sea surface temperature, precipitation and cloud cover — key to marking the location and the intensity of cyclones. IMD receives images from both the satellites every hour and uses them in its hourly bulletins. “There are some limitations with our satellites. Since Insat is geostationary and is at 36,000 km, its resolution is less. We compliment it with polar orbiting satellites,” said N Puviarasan, director, Area Cyclone Warning Centre, IMD.

For Fani, it was a good early warning system that enabled officials to save many lives, Ramesh said.

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