Each improvement means forecasts become marginally better, typically on the order of a few percentage points. Best selling book TRMM data plots latent heat in hurricane Bonnie in 1998. Calif. The Tropical Rainfall Measuring Mission satellite, a joint project between NASA and the Japanese government, profiles horizontal slices of a storm in the tropics to get a picture of how rain changes with altitude. The information is critical in forecasting how a tropical storm or hurricane might develop. When water vapor condenses into raindrops, heat is released.
Researchers call it latent heat, and it is a key factor in cloud formation and storm development.
TRMM gives researchers a verticle profile of a storm. TRMM, launched in 1997 and now eyeballing a relatively narrow swath of the tropics where hurricanes develop, is the first tool to provide such data. Tropical rainfall, which falls between 35 degrees north latitude and 35 degrees south latitude, comprises more than two-thirds of the rainfall on Earth. Researchers at Florida State University say that by adding the TRMM rainfall observations to information collected by other meteorological satellites, they can more than triple the accuracy of rainfall forecasts over the coming 12-hour period. The new method does not scuttle previously used computer models, but instead builds on them.