URI_Research_Magazine_Momentum_Spring_2015_Melissa-McCarthy

From Storm to System

by Dan Kopin

B efore Hurricane Sandy made landfall on the East Coast, the National Hurricane Center (NHC) had been tracking the storm for thousands of miles. Satellites, research buoys, storm-chasing aircraft and other weather sensors followed Sandy’s position, temperature and intensity over the Atlantic. The storm data, gathered by NHC’s weather reconnaissance network, was then processed with a complex computer model, the Hurricane Weather Research and Forecasting (HWRF) system, developed by University of Rhode Island (URI) Professor of Oceanography Isaac Ginis in collaboration with scientists at the National Oceanic and Atmospheric Administration (NOAA) National Centers for Environmental Prediction (NCEP). Government officials used the HWRF forecasts as they prepared the vulnerable coastline for the storm’s arrival.

“Hurricane forecasting is just mathematics, physics and computer science,” explains Ginis. “First, you develop an understanding of the physical processes involved. You then translate this understanding into mathematical equations. But the mathematical equations are so complex that we cannot solve those equations on a piece of paper; we need powerful computers. Many people do not realize this, but the solution to those equations is the forecast.” The HWRF is an “operational” computer model, meaning that scientists use it as a storm develops in real-time. The model assigns the Atlantic Ocean a mesh of grid points, which Ginis compares to pixels in a TV screen. As with pixels, when the grid points are closer together, there is a higher resolution. But while pixels correspond to colors, grid points correspond to locations where the storm parameters, such as wind and rain, are calculated. The grid point

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