NASA Earth Observatory map by Joshua Stevens, using IMERG data provided courtesy of the Global Precipitation Mission (GPM) Science Team’s Precipitation Processing System (PPS). Caption by Mike Carlowicz.
NASA Earth Observatory data shows that rains in Chennai in 24 hours on December 1 and 2 surpass all the records in 115 years, say from 1901, authenticating the worst-ever floods in the south Indian city.
The data collected from the Integrated Multi-Satellite Retrievals for the Global Precipitation Measurement mission IMERG shows the brightest shades indicating rainfall totals approaching 400 millimeters (16 inches) during the 48-hour period. However, NASA said its estimates may differ from earth station records.
The unprecedented deluge in Chennai caused 250 deaths and tens of thousands affected in the state of Ttamil Nadu. The animation released by NASA shows satellite-based estimates of rainfall over southeastern India on December 1–2, accumulating in 30–minute intervals.
Hal Pierce, a scientist on the GPM team at NASA’s Goddard Space Flight Center, said the highest rainfall totals exceeded 500 mm (20 inches) in an area just off the southeastern coast. While meteorologists attributed the rains to a super-charged northeast monsoon, experts at Paris conference on Climate Change were quick to link it to the growing evidence of forthcoming effects of global warming. Otherwise, the region receives 50 to 60 percent of its yearly rainfall during this winter monsoon.
However, this year the pattern was “amplified by record-warm seas and by the long-distance effects of El Niño,” said NASA scientists in a blog post. Chennai city alone recorded 1218.6 millimeters (47.98 inches) of rain in November 2015, according to Weather Underground blogger Bob Henson.
This was partly corraborated by India’s meteorological department which said the rainfall was 50 to 90 percent above normal this year. It means 345 millimeters (13.58 inches) more rains drowned Chennai last week due to a storm fueled by a low-pressure system offshore, it added.