NASA's ARIA team used satellite data acquired on September 2, 2019 to map flooding in the Bahamas in the wake of Hurricane Dorian.
While many NASA missions are tracking Hurricane Dorian as the storm heads toward the United States, some researchers are looking at what Dorian has already left behind.
The Advanced Rapid Imaging and Analysis (ARIA) team at NASA's Jet Propulsion Laboratory in Pasadena, California, in collaboration with the Singapore Earth Observatory (EOS), used synthetic aperture radar data from the Copernicus satellites. Sentinel-1 of the European Union to produce this flood.
Map of the Bahamas. The light blue color indicates areas that were likely flooded when the data was acquired on September 2, 2019. In particular, the map shows the flooding in and around Marsh Harbor in the Abaco Islands.
The map covers an area of approximately 109 miles by 106 miles (176 kilometers by 170 kilometers) shown by the large red polygon. Each pixel is approximately 32 yards (30 meters) wide. Authorities and responders can use flood maps like this as a guide to identify areas likely to be experiencing flooding; the map may be less reliable in urban or vegetated areas.
The photo below was taken on September 2 by astronauts on the International Space Station.
As Dorian developed in the Atlantic Ocean during the last week of August 2019, heading winds pushed the storm forward at a respectable rate - around 10-15 miles (16-24 kilometers) per hour. So when the hurricane passed between Puerto Rico and the U.S. Virgin Islands, damage from storm surge, rain and wind was moderate, explained NASA atmospheric scientist Marangelly Cordero-Fuentes. But as the storm approached the Bahamas, its forward movement slowed at an unbearable rate.
A nightmare scenario unfolded. The second strongest Atlantic hurricane in modern weather records stopped at Grand Bahama, the northernmost of the Bahamas Islands. In late September 1 and early September 2, Dorian was moving at just a few miles per hour and was blowing maximum sustained winds of up to 185 miles (295 kilometers) per hour. Dorian was "stationary," reported the National Hurricane Center. For 40 consecutive overtime hours, the storm loomed over the small island, lashing out with extreme rain, waves and wind.
When Dorian finally began to move north, it left a trail of catastrophic damage in the Bahamas. Preliminary assessments indicated that almost 70 percent of the homes were underwater at some point. The Red Cross reported that approximately 13,000 houses were destroyed or severely damaged.