Detecting tropical cyclone structural change with the TRMM Precipitation Radar (PR), Advanced Microwave Sounding Unit (AMSU) and Multi-satellite Precipitation Analysis (MPA)

The Extratropical Transition (ET) of a Tropical Cyclone (TC) from a warm-core, symmetric structure to a cold-core, asymmetric structure can result in intense baroclinic storms that are difficult to handle by operational forecasters. The Cyclone Phase Space (CPS) developed by Hart 2003 has shown skill in inferring TC transitions although ambiguities can result from varying depictions of the ET process between models and due to errors intrinsic within each model.

Bright band heights retrieved from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) and 0° C isotherms from the Advanced Microwave Sounding Unit-A (AMSU) are used as a surrogate for examining the warm or cold core structure as well as the symmetry of a TC that allows for a more unbiased, observational representation of ET. Results from several cases in both the North Atlantic and North Pacific basins are presented to elucidate the distinct lowering of bright band heights and freezing levels with a displacement of the warm core away from the TC center that occurs when tropical systems undergo ET.

In addition, the detailed precipitation structure of transitioning cyclones in each of the above oceanic basins will be presented with an emphasis on moisture budgets that will aid in the understanding of rainfall enhancement typically observed with these systems.