The Tropical Rainfall Measuring Mission (TRMM) satellite provides unprecedented opportunities for the study of tropical cyclone structure. Among the TRMM instruments, the TRMM Microwave Imager (TMI) provides passive microwave observations, the Precipitation Radar (PR) provides active microwave reflectivities with high vertical resolution (250 m at nadir), and the Lightning Imaging Sensor (LIS) provides observations of total lightning (both intra-cloud and cloud-to-ground). While lightning and passive and active microwave remote sensing have been used individually to study tropical cyclones in the past, they can now be used together to study the tropical cyclones observed by the TRMM satellite.
Using the TMI, PR, and LIS, precipitation features from a variety of tropical cyclones will be compared with each other and with ordinary mesoscale convective systems. One objective of this study is to understand what information from this instrument package is complimentary and what information is redundant. A primary objective is to understand where modes of tropical cyclone convection fit in the broader spectrum of tropical convection. For example, if eyewall convection displays distinctive features from outer rainband convection in the TMI, PR, and LIS data, which of these is more similar to general tropical oceanic convection?
To answer this question, indicators of the coverage and vigor of precipitation systems will be compared for the eyewall and rainband regions. These indicators include the areal coverage of specific PR reflectivities and TMI brightness temperatures, extreme values for reflectivity and brightness temperature, and measures of the vertical structure of reflectivity. Lightning occurence and flash rates will be considered in conjunction with these other indicators. After comparing these for eyewalls and rainbands, they will be compared with results from separate investigations of tropical convection.