The Spatial Contribution of Translation Speed to Tropical Cyclone Wind Structure

Fitzpatrick, P. J., & Lau, Y. H. (2014). The Spatial Contribution of Translation Speed to Tropical Cyclone Wind Structure. 31st Conference on Hurricanes and Tropical Meteorology. San Diego, CA.

The contribution of translation speed to the tropical cyclone wind structure is an important component of the storm\'s asymmetries. A literature review shows most parametric wind schemes still follow the Jelesnianski (1966) formulation, which superimposes half the translation speed at Rmax then decreases sharply to a weight of 0.1 at 100 km and 0.04 at 300 km. Some schemes will adjust Vmax at Rmax using the Schwerdt (1979) relationship which weights the contribution of translation speed to Vmax as a high ratio at slow speeds, but decreases to a moderate ratio at fast speeds. For example, the contribution of a 5-knot translation speed is 4.1 knots to Vmax (weight of 0.83), of a 15-knot translation speed is 8.3 knots (weight of 0.55), and a 25-knot translation speed is 11.4 knots (weight of 0.46). However, the Schwerdt relationship contains no radial or intensity dependence. Both the Schwerdt and Jelesnianski relationships appear to be formulated qualitatively based on experience and apparent reasonableness of results, not on a data analysis. Using H*WINDS, we have taken a first step in developing simple empirical weight equations based on wind asymmetries, intensity, and translation speed. These results will be presented at the conference.