Science and Technology News

Monday, November 1, 2010

Hurricane Season 2010: Tropical Storm Anggrek (Southern Indian Ocean)

Infrared View of Southern Indian Ocean's Second Tropical Storm Reveals Icy Cloud Tops

Tropical Storm Anggrek is moving through open waters of the Southern Indian Ocean, and NASA's Aqua satellite captured took the temperature of its cloud tops to get an indication of how strong the storm has become. Anggrek is the second tropical cyclone of the Southern Indian Ocean cyclone season, which officially doesn't start until Nov. 15.

Cold thunderstorm cloud tops with a tropical cyclone are an indication of whether a storm is strengthening or weakening. Since Anggrek formed over the weekend, infrared satellite imagery has confirmed that its cloud tops have grown colder. That's an indication that there is stronger uplift in the storm (rapidly rising air that forms the thunderstorms that power a tropical cyclone) than there was 24 hours before.

NASA's Aqua satellite flew over Tropical Storm Anggrek on Nov. 1 at () and it was the Atmospheric Infrared Sounder (AIRS) instrument that captured data on the storm. In addition to the very cold cloud tops as cold as or colder than 220 Kelvin or minus 63 degrees Fahrenheit (F), the infrared image revealed warm waters of more than 80 degrees Fahrenheit (threshold for maintaining tropical cyclones).

On Nov. 1 at 0900 UTC (), Tropical Storm Anggrek had maximum sustained winds near 50 knots (57 mph) with higher gusts. It was located about 100 nautical miles north-northeast of the Cocos Islands near 10.9 South and 97.5 East and has tracked southward at 7 knots (8 mph). The storm has been able to strengthen because vertical wind shear has eased.

The Joint Typhoon Warning Center forecasts the storm to intensify into a cyclone before moving over cooler waters when it approaches 15.0 South and wind shear will increase thereafter. By the end of the week, those forecasters believe that environmental conditions will dissipate the storm in open waters.

Text Credit: Rob Gutro
NASA Goddard Space Flight Center, Greenbelt, MD

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