Climatological analysis of tropical cyclone eye and inner-core structure from a global satellite-based passive microwave dataset

Passive microwave observations of tropical cyclones (TCs) from polar-orbiting satellites have been available to analyze vortex structure and evolution since 1987, and are now a routinely-utilized product in most global TC forecast centers. For the most part, analysts rely on subjective interpretation of the imagery to infer convective structure and banding features to infer intensity and trends in vortex organization. While resources such as the NRL TC webpage (http://nrlmry.navy.mil/TC.html) and Morphed Integrated Microwave Imagery at CIMSS (MIMIC-TC; http://tropic.ssec.wisc.edu/real-time/mimic-tc/tc.shtml) allow timely analysis of TC structures using passive microwave imagery, there remains a lack of objective structural metrics regarding the interpretation of this information.

This study provides some preliminary steps towards the development of a global climatology of TC structures from passive microwave imagery based on objective measures. Our dataset consists of a newly developed global standardized digital archive of TCs as observed by multiple passive microwave imagers (including SSM/I, SSMIS, TMI, and AMSR-E) since 1987. For each image, a reanalysis of the center location and eye size is performed by an automated algorithm (ARCHER, Wimmers and Velden 2010). Multiple objective characterizations of the eye and core size, asymmetry, and strength are tested and compared to the ARCHER analysis. Using these metrics, the first global inter-comparison of TC eye and inner-core structures will be discussed.