The 23rd Conference on Hurricanes and Tropical Meteorology

10A.3
STRUCTURAL CHARACTERISTICS OF MESOSCALE CONVECTIVE SYSTEMS ASSOCIATED WITH TROPICAL CYCLOGENESIS

Patrick A. Harr, Monterey, CA; and R. L. Elsberry and D. Milot

Three conceptual models have been developed to define the relative roles of mesoscale convective systems (MCSs) and large-scale circulation characteristics in tropical cyclogenesis in the monsoon environment of the western North Pacific. The hierarchy of the
conceptual models is such that at one extreme MCS activity is the primary contributor to tropical cyclone formation. At the opposite extreme, the major contributor is the synoptic-scale circulation. In between are situations in which MCS activity acts in tandem with
favorable synoptic circulations. Beyond the roles of each contributor to tropical cyclone formation, there appears to be a relationship between the mature tropical cyclone structure and the manner in which formation occurred.

The primary characteristics during genesis that influence the wind structure at maturity are the relative roles of the synoptic-scale circulations and individual MCSs. A major limitation to refinement of the roles played by MCS activity is the lack of data over regions where MCS activity is related to tropical cyclogenesis. Therefore, detailed structural characteristics that may define when and how MCS activity could be related to tropical cyclone formation over the western North Pacific are difficult to identify. In this research, combinations of polar-orbiter microwave and geostationary satellite visible and infrared data are used to define MCS structural characteristics such as convective and stratiform cloud areal amounts, percent coverage, and rain rates. Furthermore, co-located microwave and infrared imagery are used to calibrate the infrared imagery, which then allows for hourly estimates of these parameters to be defined from subsequent infrared images throughout the lifetime of the MCS. The infrared imagery is re-calibrated each time a co-located microwave image is available

Detailed time evolutions of MCS structure characteristics will be presented, such as amounts of stratiform and convective clouds and time-integrated rain rates from each cloud type. Comparisons are made between MCSs that are associated with tropical cyclone formation in each type of conceptual model. Furthermore, comparisons are made with MCSs in circulations that do not result in tropical cyclone formation. Results suggest that there are significant differences in structural characteristics such as time-integrated rain rates from each cloud type between MCSs associated with tropical cyclone formation and those not associated with formation.

The 23rd Conference on Hurricanes and Tropical Meteorology