Physical interpretation of objectively defined tropical cyclone structural features in passive microwave satellite imagery

The use of structural pattern matching and feature extraction from analysis of tropical cyclone (TC) images has a long history (e.g., Wexler 1947, Fett 1964, Black et al. 1972, Dvorak 1975). While it is most commonly applied to intensity estimation (e.g., Dvorak 1975, Olander and Velden 2007, Ritchie et al. 2012, Velden and Herndon 2014), analysis of patterns is also sued to explore the taxonomy of storms, including investigations of spiral banding (Senn and Hiser 1959), eyewall shapes (Lewis and Hawkins 1982), multiple eyewalls (Hawkins et al. 2006), and annular storms (Knaff et al. 2008). Recent efforts at NRL (Bankert and Hawkins 2012) seek to synthesize these efforts into objective analysis schemes to provide near real-time satellite-based diagnostics of intensity and structure. Leveraging a standardized digital database of global TCs in microwave imagery, a variety of research schemes that builds upon previous work are used to provide automated retrieval of TC features, including the use of image processing techniques, descriptive statistics, symmetric decomposition, and morphometrics.

The present study examines the physicality of these microwave-based TC structural features by relating their significance to the meteorological evolution of the storm. Examples of features that have a statistically significant relationship with intensity (change) will be described along with representative TC satellite imagery. Basic climatological representations of such features are shown, including occurrence by basin and time of year. The changing occurrence of these features through the TC lifecycle will also be shown, highlighting the specific features that represent different phases of TC evolution. Such objective identification of structural metrics may be useful in intensity analysis and prediction schemes, as well as providing guidance for possible structure analysis and forecasting.