Meeting Documents

Evaluation of Surface Heat Flux Products Using Long-Term Moored Data on the West Florida Shelf

Abstract

The net surface heat flux and its constituents from six global products were evaluated using long-term moored observations on the West Florida Continental Shelf (WFS), as part of the Coastal Ocean Monitoring and Prediction System (COMPS) maintained by the College of Marine Science, University of South Florida. Three reanalysis products were selected: the Modern-Era Retrospective analysis for Research and Applications Version 2 (MERRA2), the National Center for Environmental Prediction-Department of Energy reanalysis (NCEP/DOE), and the Fifth-generation European Center for Medium-range Weather Forecast Reanalysis (ERA5). Additionally, two satellite-based products, the SeaFlux v3 Data Product and the Objectively Analyzed Air-Sea Fluxes (OAFlux), along with one ocean model from the Estimating the Circulation and Climate of the Ocean (ECCO) project, were included in the analysis. Overall, there is good agreement between the six global products and observations in the monthly mean climatologies of the air-sea fluxes. MERRA2 and ERA5 reanalysis products accurately capture the spring and fall transition onsets, in February and August, when the sign of the net heat flux changes. In contrast, all other global products reproduce the general shape of the seasonal cycle, but the spring and fall transitions are shifted one month later in the year. The MERRA2 product's surface net heat flux shows the best agreement with the observations. However, this accuracy does not result from precise individual constituents; rather, it is due to the compensation of underestimated cooling in the turbulent flux and underestimated heating in the radiative flux. Interestingly, all six global products underestimate turbulent flux cooling, especially during the summer months. This underestimation is due to the combined effect of winds being significantly weaker than observed and smaller air-sea differences in specific humidity. To enhance the quality of these global gridded products, improvements in the air-sea variables used to construct them, particularly surface winds and specific humidity, are necessary.