Assessing high-resolution analysis of surface heat fluxes in the Gulf Stream region

Abstract

A satellite-based global analysis of high-resolution (0.25°) ocean surface turbulent latent and sensible heat fluxes was developed by the objectively analyzed air-sea fluxes (OAFlux) project. Resolving air-sea flux down to the order to 0.25° is critical for the description of the air-sea interaction on mesoscale scales. In this study, we evaluate the high-resolution product in depicting air-sea exchange in the eddy-rich Gulf Stream region. Two approaches were used for evaluation, one is point-to-point validation based on six moored buoys in the region, and another is basin-scale analysis in terms of wave number spectra and probability density functions. An intercomparison is also carried out between OAFlux-0.25°, OAFlux-1°, and four atmospheric reanalyses. Results indicate that OAFlux-0.25° is able to depict sharp oceanic fronts and has the best performance among the six participating products in comparison with buoy measurements. The mean OAFlux-0.25° differences in latent and sensible heat flux with respect to the buoy are 7.6 Wm−2 (7.7%) with root-mean-square (RMS) difference of 44.9 Wm−2, and 0.0 Wm−2 with RMS difference of 19.4 Wm−2, respectively. Large differences are primarily due to mismatch in SST between gridded data and point measurements when strong spatial gradients are presented. The wave number spectra and decorrelation length scale analysis indicate OAFlux-0.25° depicts eddy variability much better than OAFlux-1° and the four reanalyses; however, its capability in detecting eddies with smaller scale still needs to be improved. Among the four reanalyses, CFSR stands out as the best in comparison with OAFlux-0.25°.