The hurricane churns the water beneath it, bringing cooler water up to the surface from below and leaving a “cold wake” behind the storm. Hurricane-ocean interaction: A hurricane affects its own intensity by interacting with the ocean. The research group at URI has also made important contributions towards improving the air-sea fluxes in the GFDL model. The GFDL/URI fully-coupled hurricane-ocean prediction system became operational in 2001. This coupling of the atmosphere with the ocean enables the model to reproduce the cooling of the ocean surface beneath the hurricane, which has an important impact on hurricane intensity. In 1996, a collaboration began between scientists at GFDL and the University of Rhode Island (URI) to couple the atmospheric hurricane model to the Princeton Ocean Model. This area of fine resolution moves with the hurricane, keeping the storm centered in the middle of the innermost computational grid.Ĭoupling the atmosphere to the ocean in the hurricane model The size of the outer mesh is ~5000 miles wide with grid points spaced about 30 miles apart, while the finest mesh, where the grid points are spaced only 5 miles apart, covers a 325-square mile area. The current GFDL hurricane model is a gridpoint model that consists of three computational meshes which are nested together with increasingly finer grid-point spacing in each mesh. Since becoming operational in 1995, the GFDL hurricane model has played a major role in improving hurricane prediction, resulting in a significant reduction in track forecast error. In the mid-1980s, GFDL scientists began a 10-year effort to transform their research model into an operational hurricane forecasting tool for the National Weather Service. Results from real-data simulations and forecasts strongly suggested the potential of improving hurricane prediction with a comprehensive three-dimensional model. Throughout the next decade, many idealized numerical experiments demonstrated the capability of this model to produce a realistic hurricane structure, although it would not be until the 1980s that simulations would be attempted using data from real storms.

An axisymmetric hurricane model was constructed first, and then in 1973 experiments were made with a three-dimensional model. The hurricane dynamics group at GFDL was formed under the leadership of Yoshio Kurihara for the purpose of performing hurricane research through numerical modeling. The GFDL hurricane prediction system originated as a research model in the 1970s. History of the GFDL Operational Hurricane Prediction System These include the inflow of low-level air into the hurricane’s inner core region the supply of the storm’s energy from the evaporation of water from the ocean surface updrafts of warm, moist air that feed thunderstorms in the core region of the storm, which help to intensify the hurricane and the outflow of cooler, drier air at upper levels of the troposphere: The GFDL hurricane model is able to reproduce the features that are important in a hurricane. One of the biggest challenges for hurricane modeling is creating a model that can accurately depict the large-scale, environmental flow of the atmosphere that is largely responsible for steering the hurricane, while at the same time representing the finer scale details of the inner core region that determine the intensity of the storm. Mathematical equations can approximately describe the various motions and interactions that occur in the atmosphere. The laws of physics dictate the manner in which that motion takes place. The atmosphere is a fluid of air parcels in constant motion.

The challenge of representing a hurricane in a numerical model Since 1995, the GFDL Hurricane Prediction System has been used operationally by the National Hurricane Center and has consistently been one of the top-performing models utilized by NHC. Much of this progress is due to advances in numerical weather prediction, that is, the use of computer models which approximate the fluid motions of the atmosphere to create forecasts of the weather at some time in the future.

Over the past 20 years, significant advances have been made in the science of hurricane track forecasting. Operational Hurricane Track and Intensity Forecasting

Hurricane track models spaghetti