Tropical cyclones giving up their secrets

Wednesday 23rd Nov 2011 by theWeather Club

Researchers at the US Naval Research Laboratory Marine Meteorology Division (MMD) in California have developed the snappily named 'Coupled Ocean/Atmosphere Mesoscale Prediction System Tropical Cyclone' model (COAMPS-TC for short). This new model has achieved a significant research milestone in predicting the intensity and structure of tropical cyclones – or hurricanes as they are known in that part of the world.

While the predictions of the paths of hurricanes have steadily improved over the last few decades, improvements in the predictions of storm intensity have proven much more difficult. "Over the past two years, the COAMPS-TC model has shown to be the most accurate emerging research model for predicting tropical cyclone intensity," said Dr Jim Doyle, research meteorologist at NRL Monterey. "There is no better example of these difficult challenges than the intensity predictions for Hurricane Irene this past August." Producing very accurate intensity predictions during a real-time experimental demonstration of Hurricane Irene, COAMPS-TC intensity predictions were out by six knots on average for a series of three-day forecasts. This was a clear improvement over the official National Hurricane Centre (NHC) forecast and other operational models, where errors ranged from 20-30 knots.

The successful predictions have demonstrated that Numerical Weather Prediction (NWP) models – of which COAMPS-TC is one – can outperform operational statistical-dynamic models that are based on climatology and previous behaviour. It is further believed that NWP models, which predict the location, dynamics and intensity of a storm, will eventually provide the most promising approach to achieving accurate hurricane intensity and structure prediction.

It is all very high tech stuff, and in June of this year COAMPS-TC was one of nine worldwide winners of the first High Performance Computing (HPC) Excellence Award presented at the International Supercomputing Conference (ISC) in Germany, an award presented annually to recognise noteworthy achievements by users of HPC technologies. COAMPS-TC was recognised for achieving "a significantly improved model for tropical cyclone forecasting".

It is an important development which could have huge financial benefits. In 2011, the United States alone suffered 14 weather disasters with a final damage bill exceeding one billion dollars. Anything which can improve our knowledge of the path and internal nature of an oncoming storm, and therefore help minimise damage when it arrives, will be extremely welcome by all concerned. While still early in its development, we will be hearing a lot more about the COAMPS-TC model in the hurricane seasons to come.