NASA's Aqua Satellite instrument sees Paloma's colder clouds
by Rob Gutro, NASA's Goddard Space Flight Center


photo by NASA/JPL

The Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua satellite is working overtime with Hurricane Paloma. AIRS produced infrared and visible images, taken on November 8 at 1:29 p.m. EDT (18:29 UTC) about 6 hours before its center made landfall in Cuba.

The infrared image shows the frigid cloud top temperatures, giving forecasters a clue to the storm's strength. The lowest temperatures (in purple) are associated with Paloma's high, cold cloud tops. Those areas are as cold as 220 degrees Kelvin or minus 63 degrees Fahrenheit (F) or colder. The blue areas are around 240 degrees Kelvin, or minus 27F.

The National Hurricane Center uses cloud temperature as one factor in determining whether a tropical cyclone is strengthening. When cloud temperatures get colder, it means that clouds are getting higher. Building clouds indicate a lot of "uplift" in the atmosphere and stronger thunderstorms.

AIRS's infrared signal doesn't penetrate through clouds, so where there are clear skies AIRS reads the infrared (heat) signal from the ocean and land surfaces, revealing warmer temperatures (colored in orange and red). The orange temperatures are 80F (300 degrees Kelvin) or greater (the darker they are, the warmer they are). Tropical cyclones need sea surface temperatures of 80F to strengthen and maintain their strength.

photo by NASA's Jesse Allen, MODIS Rapid

This image of Paloma was captured by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite on November 6, 2008. At the time of the image, the storm had a loosely organized appearance, with an obvious pattern of rotation, but no distinct eye. This was captured before Paloma hit the Cayman Islands.