Simple diagnosis of tropical cyclone structure via pressure gradients

Abstract

In 1980 the Holland tropical cyclone (TC) wind profile model was introduced. This simple model was originally intended to estimate the wind profile based on limited surface pressure information alone. For this reason and its relative simplicity, the model has been used in many practical applications. In this paper the potential of a simplified version of theHolland B parameter, which is related to the shape of the tangential wind profile, is explored as a powerful diagnostic tool for monitoring TC structure. The implementation examined is based on the limited information (maximum wind, central pressure, radius and pressure of the outer closed isobar, radii of operationally important wind radii, etc.) that is typically available in operational models and routine analyses ofTCstructure.This "simplifiedHollandB" parameter is shown to be sensitive toTCintensity, TC size, and the rate of radial decay of the tangential winds, but relatively insensitive to the radius ofmaximum winds.Aclimatology of the simplifiedHollandBparameter based on historical best-track data is also developed and presented, providing the expected natural ranges of variability. The relative simplicity, predictable variability, and desirable properties of the simplifiedHollandBparametermake it ideal for a variety of applications. Examples of howthe simplifiedHollandBparameter can be used for improving forecaster guidance, developing TC structure tools, diagnosing TC model output, and understanding and comparing the climatological variations of TC structure are presented. © 2011 American Meteorological Society.