Technology Helps Predict Hurricane Paths

ByABC News
September 19, 2000, 2:32 PM

Sept. 20, 2000 -- Tropical depressions are known to lurk under cloud cover before emerging into view as the destructive seeds of a hurricane. The cloud cover has long crimped forecasters efforts to warn of developing hurricanes.

But two NASA satellites, originally deployed to track climate, are now helping meteorologists see through the clouds and detect these young storms.

Getting the Picture

If [a depression] is below a high canopy of clouds, many times we didnt even know it was there, says Evan Forde, an oceanographer at NOAAs Atlantic Oceanographic and Meteorological Laboratory.

Hurricane forecasters have begun using microwave technology from the two satellites to peer through cloud cover and view the underlying weather conditions that drive hurricanes: wind and rainfall. Data from NASAs Quikscat satellite, determines wind speed and direction while data from the Tropical Rainfall Measurement Mission satellite (TRMM) provides information about the amount of rainfall in a given area.

Quikscat works by using a device called a scatterometer that sends beams of microwave radiation down at an angle to the ocean surface below. A rough ocean bounces the scattered beams back to the satellite; the more scattered the beams, the rougher the seas. The scatterometer also detects the direction of the wind, to see if it is blowing in a complete circle, which indicates a tropical depression.

Military, Sea-Faring Use

Timothy Liu, project scientist for the Quikscat mission at NASAs Jet Propulsion Laboratory, says the satellite, launched last year at the cost of $19 million for the entire mission, was designed to study how ocean currents affect global climates. Quikscat provides forecasters with enough information to identify the early signs of swirling storms 46 hours, or almost two days, before previous data, according to NOAA scientists. And when the orbits of the Quickscat and TRMM satellites overlap, their wealth of data offer an unusually clear picture of the swirling vortexes of hurricanes.