Surface Fluxes and Boundary Layer Recovery in TOGA COARE: Sensitivity to Convective Organization

Shipboard radar data collected during the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE) are used in conjunction with surface meteorological data from the Woods Hole Oceanographic Institute's IMET buoy to describe in detail how three classifications of convective systems modify the surface fluxes of heat, moisture, and momentum. The classifications of convection were based on spatial-scale [sub-mesoscale convective system (MCS) vs MCS scale], horizontal morphology (nonlinear vs linear organization), and the presence of stratiform precipitation as determined by quantitative radar data. Three types of convective organization were examined; sub-MCS-scale nonlinear events and MCS-scale linear events with and without significant stratiform precipitation. These three classifications were present about 90% of the time and produced over 90% of the rainfall during TOGA COARE, as determined by shipboard radar. Composite analyses of the surface fluxes along with the pertinent bulk variables have been constructed for each of these classes of convective organization. During the compositing process, the convectively active and recovery periods were separated, allowing these distinctly different phases to both be represented in the final composite analyses. The sensible and latent heat flux enhancements were decomposed through perturbation analyses and the relative importance of each term during the convectively active and recovery phases was also assessed.