A new analytical technique. Each improvement means forecasts become marginally better, typically on the order of a few percentage points. But when next hurricane season rolls around, a new and unusual breed of satellite data could allow an unprecedented jump in forecast accuracy, according to a report being presented Tuesday at the annual meeting of the American Meteorological Society's meeting in Long Beach, California. 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, 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. Researchers examined the behavior of a number of different forecast models and selected those properties from each model that lead to the true rainfall as observed by the TRMM satellite during past storms.