Satellite-Based Analysis of a Warm Conveyor Belt in a Marine Extratropical Cyclone

Abstract:

Extratropical cyclones play a paramount role in Earth’s climate through meridional energy transport from the equator to the poles, as well as through cloud and precipitation formation by providing a majority of observed precipitation in the midlatitudes. The warm conveyor belt is a poleward airstream of ascending moisture that rises from the boundary layer to the upper troposphere. It is responsible for transporting a preponderant amount of water vapor present in an extratropical cyclone, with nearly 100% efficiency at precipitating all transported moisture. The community’s understanding of marine extratropical cyclones and their synoptic dynamics originates from the Shapiro and Keyser Model, but there is less understanding of the mesoscale evolution of the cloud and precipitation structures within an extratropical cyclone and its warm conveyor belt.

This research aims to better understand extratropical cyclone and warm conveyor belt evolution on the mesoscale using a specific case study. In late November 2006, a marine extratropical cyclone formed east of Florida in the Atlantic Ocean, travelling parallel to the eastern seaboard for nearly a week. Model analysis showed the presence of a strong warm conveyor belt associated with the cyclone. Given that the system remained in nearly the same longitudinal position, it was observed multiple times by NASA’s Afternoon-Train (A-Train) satellite constellation. CloudSat radar reflectivity profiles and ECMWF-AUX thermodynamic fields show a transition from stratiform to convective precipitation along the northern edge of the conveyer belt, with larger vertical instability and isolated higher rain rates. Examination of the storm scale context indicates this convection may develop in place rather than via interaction with the cold front. These results give us a better understanding of structural evolution of clouds and precipitation as it interacts with the cyclone-scale dynamics and surrounding thermodynamic environment.