On the use of NCEP-NCAR reanalysis surface marine wind fields for a long-term North Atlantic wave hindcast

This paper uses a state-of-the-art. third-generation wave model to evaluate the marine surface wind fields produced in the National Centers for Enviro nmental Protection-National Center for Atmospheric Research (NCEP-NCAR) Rea nalysis (NRA) project. Three alternative NRA wind fields were initially con sidered by assessing the resulting wave hindcasts against wave measurements in the North Atlantic Ocean. The surface 10-m wind field was found to be t he most skillful and was selected for further analysis. While the wind fields from the NRA were found to be at least as skillful as the best of the analyses produced by operational Numerical Weather Predict ion centers, they had significant deficiencies when compared to kinematical ly analyzed wind fields carried out in detailed hindcast studies. Storm pea k wave heights in extratropical storms were systematically underestimated a t higher sea states due to underestimation of peak wind speeds in major jet streak features propagating about intense extratropical cyclones. In addit ion, in situ data were incorrectly assimilated and tropical cyclones were p oorly resolved. In this study an intensive kinematic reanalysis was carried out in which wi nd fields in extratropical storms were intensified as necessary, in situ su rface wind data were correctly reassimilated, and tropical cyclone boundary layer winds were included. Comparisons with in situ buoy measurements and satellite altimeter data sho w clear improvements in both bias and scatter in the wave hindcasts using t he kinematically reanalyzed wind fields, particularly in the higher sea sta tes. Furthermore. the hindcast wind and wave climatologies closely resemble those obtained from measured wind and wave data from buoys and offshore pl atforms.