Heat Fluxes in Tampa Bay, Florida

The Meyers et al. (2007) Tampa Bay Model produces water level and three-dimensional current and salinity fields for Tampa Bay. It is capable of computing temperature but is presently run without active thermodynamics. Variations in water temperature are driven by heat exchange at the water-atmosphere boundary and advective heat flux at the mouth of the bay. The net heat exchange surface boundary condition is required for computations of three-dimensional temperature fields. Components of the surface heat budget were measured or derived at an observational tower in Middle Tampa Bay. Net heat exchange at the surface of Tampa Bay was computed from June 2002 to May 2005. Total heat energy gained or lost at the bay-atmosphere interface includes turbulent and radiative heat fluxes. An initial examination of turbulent heat exchange, the portion of total surface heat flux driven by atmospheric turbulence, demonstrated the skill of a bulk flux algorithm (TOGA COARE v. 3.0) in predicting measured sensible heat flux over Tampa Bay (R² = 0.80 and RMSE of 11.02 W/m² from June through November of 2002). Insolation was measured directly at the observational tower. Solar radiation is reflected in proportion to sea surface albedo, computed following Payne (1972). Based upon Secchi depth readings, Tampa Bay was classified as a water body type 7. The amount of penetrating insolation reflected from the bottom was computed for this type 7 estuary. Upwelling longwave radiation is emitted in proportion to the water temperature according to the Stefan-Boltzmann law. Eleven bulk formulas for computing downwelling longwave radiation were assessed for skill in reproducing observations made at buoys moored on the West Florida Shelf. Berliand and Berliand (1952) best represented downwelling longwave heat flux measurements at the buoys and is appropriate for application over Tampa Bay. Surface heat flux dominates cooling in fall and warming in spring while advective heat exchange becomes important during the summer. Extreme events, including tropical cyclones and extratropical fronts, dramatically impact surface heat exchange, driving rapid cooling. The methods applied in computation of heat flux components are amenable to real-time modeling exercises