Exploring a Comparative Climatology of Tropical Cyclone Core Structures

The structure of a tropical cyclone (TC) is a spatial representation of its organizational pattern and distribution of energy acquisition and release. This fingerprint depicts a specific phase in the TC's meteorological lifecycle, reflecting its past and potentially constraining its future development. For a number of reasons, a thorough objective definition of TC structures (especially at the TC core) and an intercomparison of their varieties have been neglected. This lack of knowledge impedes a fuller understanding of TCs, possibly signaling a key reason why TC intensity forecasts, despite numerical model improvements and theoretical advances, have been stagnant in recent years relative to track forecasts. To improve the understanding and forecasting of tropical cyclones, this research aggregates known methods to identify structure and proposes expanded metrics of structural diagnosis. A 24 year record of limited operational core structure attributes - including aircraft reconnaissance measurements and estimates by operational forecasters - are examined and shown to tease the potential capability of TC structure to guide analysis and forecasting. To mitigate these data set limitations, a new global 26 year multi-platform dataset of satellite microwave imagery is gathered and standardized to facilitate an expanded climatological survey of tropical cyclone structures. New types of structure metrics are objectively developed using morphometric analysis techniques (i.e. size and shape analysis of TC features) based on known tropical cyclone critical features, thereby facilitating a comparison with operational data. A climatology of TC core structures is presented, demonstrating the observed existence of intensity, size, and shape information in aircraft and satellite data. Composites of relationships between intensity and size metrics show preferred configurations that depend on a TC's structural state. While the newly defined structures provide additional dimensionality that is related to intensity, some TC size relationships are shown to be invariant with intensity. This comparative analysis of observed structural metrics provides further insight in understanding the relationship between TC structural features, to what extent they indicate intensity change, and what physical processes lead to their formation and decay.