National Oceanic and
Atmospheric Administration
United States Department of Commerce


FY 2008

Surface heat fluxes from the NCEP/NCAR and NCEP/DOE reanalyses at the KEO buoy site

Kubota, M., N. Iwabe, M.F. Cronin, and H. Tomita

J. Geophys. Res., 113, C02009, doi: 10.1029/2007JC004338 (2008)

Surface heat fluxes from the Kuroshio Extension Observatory (KEO) buoy are compared with surface heat fluxes from the National Centers for Environmental Prediction (NCEP)/National Center for Atmospheric Research reanalysis (NRA1) and NCEP/ Department of Energy reanalysis (NRA2). KEO surface measurements include downward solar and longwave radiation, wind speed and direction, relative humidity, rain rate, and air and sea surface temperature. For solar radiation, NRA2 had better agreement with KEO than NRA1. Both reanalyses underestimated shortwave radiation in summer and slightly overestimated it in winter. Turbulent surface heat fluxes are estimated with the KEO surface data using the Coupled Ocean-Atmosphere Response Experiment (COARE) version 3.0 bulk algorithm. Both NRA1 and NRA2 latent heat flux (LHF) are larger than KEO LHF, consistent with previous studies. However, the comparison shows larger errors than previously thought. Indeed, the latent heat flux bias for NRA1 is 41 W m-2 and for NRA2 is 62 W m-2 (indicating that the bias between NRA1 and NRA2 is 21 W m-2). For latent heat flux, the large bias is caused primarily by the NRA bulk flux algorithm, while the root mean square (RMS) error is caused primarily by errors in the NRA meteorological variables. The combination of the biases for each heat flux is such that total NRA heat transfer from the ocean to the atmosphere is considerably larger than observed by KEO. These results highlight the importance of maintaining in situ observations for monitoring surface heat fluxes in the Kuroshio/Kuroshio Extension regions.

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