HYDERABAD: Nasa , which tracked cloud bands over India using multiple satellites for measuring precipitation, has found that Kerala received 46.9 centimetre of weekly rainfall from August 13 to August 20 due to concentrated cloud bands that resulted in flooding.

A video released by the agency on Wednesday provides an estimate of rainfall and shows the spread of the resulting severe flooding in Kerala, and parts of Karnataka.

Nasa Goddard Space Flight Center experts wrote on their blog, “Rainfall accumulation in the week from August 13 to 20 showed two cloud bands of heavy rains across India. While the first band, which appeared much broader and extends across the northern part of the peninsula, received 120mm of rainfall on NorthWest and 350mm on east towards the Bay of Bengal. The second cloud band is heavily concentrated and intense near the southwest coast of India and the Western Ghats where onshore flow was enhanced by an area of low pressure embedded within the general monsoon.,”

Rainfalls in the cloud band over southwest that covers Kerala and Karnataka was more than 250mm, and exceeded in the core area to more than 400mm. The maximum estimated value from IMERG (Integrated Multi SattelitE Retirevials Globals Precipitation Measurement) was 469mm.

Dr K Nagaratna, Director Meterological centre, Hyderabad, who anaysed Nasa's video, told TOI ,”Nasa has given figures of weekly rainfall. Heavy precipitation of clouds over the Western Ghats during the week resulted in flooding. The severity of southwest Monsoon cloud band is moreover Kerala and parts of Karnataka due to moisture aided from the Arabian Sea. Usually, this is the season during which west coast received the heaviest rainfall. The Southwest coast region remains wet during most of the monsoon,”

Nasa explained that the contributing factory to the heavy rains along southwest coast is the Western ghats.

“Though much smaller than the Himalayas, Western Ghats parallel to the West Coast of India with many peaks over 6,500 feet. The Western Ghats enhance rainfall along the West Coast of India as they intercept the moisture-laden air being drawn in off the warm waters of the northern Indian Ocean and the Arabian Sea as part of the monsoon circulation,” Nasa experts said.

As part of IMERG Nasa used passive microwave sensors and geostationary infrared data. Global Precipitation Measurement programme is a joint mission between Nasa and that of Japan’s Aerospace Agency (JAXA).

