The Need to Relate Tropical Cyclone Dynamics to Satellite-Observed Cloud Patterns: Why Does the Dvorak Technique Work?

The Dvorak Technique for estimating the intensity of tropical cyclones (TCs) from visible and infrared satellite imagery is used operationally by TC warning centers worldwide. It relates observed TC cloud patterns to the intensity through several sets of relationships and rules, and it has an excellent success record since its creation more than 40 years ago. Despite the success, the technique is based mainly on statistics and empiricism, and it lacks a rigorous understanding of how the cloud patterns and the technique rules are tied to TC dynamics. Such ties must exist, though, since otherwise the technique would not work at all!

This paper points to the numerous questions that need answering regarding the relationship of TC dynamics to various aspects of the technique. These would include “Do the constraints in the Dvorak Technique have an underlying physical reality?” and many variations on “Why do certain cloud patterns correspond to specific TC intensities?” Another important question is “What is the relationship between three-dimensional TC structure/dynamics and the various Dvorak Technique cloud patterns?” Answering these and other questions will help link the abundant research done on TC structure and evolution to the operational tasks of TC intensity and structural analysis, and this should lead to improvements in the Dvorak Technique. These answers would also pave the way for updated versions of the Dvorak Technique based on more modern types of satellite data.