Atmospheric and Environmental Sciences Professor Receives U.S. Navy Office of Naval Research Grant

John E. Molinari
Atmospheric and Environmental Sciences

Sponsor:     U.S. Navy Office of Naval Research
Dates:         January 1, 2014 – December 31, 2016
Amount:     $375,000

Outflow Layer Dynamics and Thermodynamics and Tropical Cyclone Intensity Change

We propose to undertake four projects that relate to the role of the tropical cyclone outflow layer on subsequent intensity of the storms. The first extends our previous work from many years ago on the relationship between outflow layer fluxes of angular momentum and intensity change in tropical cyclones 24-36 hours later. The second project will examine the relationship between convective outbreaks at the storm core and the evolution of outflow. Of particular interest are occasions when enhanced outflow precedes enhanced convection at the core. These events are likely to represent outflow layer forcing of the storm. The third proposed project evaluates the ability of the NOGAPS and COAMPS models to simulate the outflow layer, especially with regard to heat and momentum fluxes. The final project investigates the development of turbulence associated with the outflow layer central dense overcast (CDO). Preliminary work indicates that diabatic forcing within the CDO, including cloud-top longwave cooling, within-cloud longwave warming, and especially below-cloud sublimation-induced cooling, drive alternating unstable and stable layers. The unstable layers frequently contain Richardson numbers below 0.25, indicating certain turbulence. Using Global Hawk sondes, we will investigate the structure, diurnal variation, and diabatic physics of these layers.