NOAA to use new way to predict hurricane’s punch

Published 12:00 am Wednesday, March 17, 2010

BATON ROUGE, La. (AP) — How much storm surge will a hurricane drive ashore? How much rain will a hurricane that lands on the Gulf Coast bring to places as far inland as Kentucky or the Northeast? When will a monster hurricane suddenly dissipate from a record-maker to a dud?

The answers to many of these questions often are tied to knowing how much moisture swirls in the atmosphere around a hurricane churning across the ocean.

This hurricane season, for the first time, researchers with the National Oceanic and Atmospheric Administration say they will use Global Positioning System technology to measure the dynamics of airborne moisture far offshore in the Gulf of Mexico, and track the fuel available to ramp up tropical systems moving through the Gulf.

“GPS has enabled a revolution in the way we do a lot of things,” said Seth I. Gutman, a physical scientist and chief of NOAA’s GPS-Met Observing Systems Branch in Boulder, Colo. Better use of GPS to measure moisture for hurricane forecasting has been “a long time coming,” he said at a hurricane conference at Louisiana State University on Tuesday.

NOAA and LSU researchers collaborated to install GPS weather stations on two offshore oil platforms in the Gulf of Mexico this winter. The stations will give meteorologists the first ever over-the-Gulf moisture readings, Gutman said.

This is done by measuring the time it takes radio signals transmitted by satellites 22,000 miles away to reach the GPS stations in the Gulf. Moisture causes a radio signal to bend and slow down.

“It’s kind of like launching a weather balloon every second of the day,” said Roy Dokka, the executive director of LSU’s Center for GeoInformatics and a collaborator on the experiment.

For hurricane forecasters, how much moisture or dry air a hurricane will suck in is a life-or-death question.

“The energy contained in a hurricane is related to the amount of moisture in the storm. We call it moisture flux,” Gutman said. “It’s the exchange of moisture in the open ocean, and the exchange of moisture between the oceans and the atmosphere that determines whether or not there is the energy to sustain a storm, to intensify it, to reduce it.”