On the Use of NCEP–NCAR Reanalysis Surface Marine Wind Fields for a Long-Term North Atlantic Wave Hindcast

Abstract

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 Environmental Protection?National Center for Atmospheric Research (NCEP?NCAR) Reanalysis (NRA) project. Three alternative NRA wind fields were initially considered by assessing the resulting wave hindcasts against wave measurements in the North Atlantic Ocean. The surface 10-m wind field was found to be the 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 Prediction centers, they had significant deficiencies when compared to kinematically analyzed wind fields carried out in detailed hindcast studies. Storm peak wave heights in extratropical storms were systematically underestimated at higher sea states due to underestimation of peak wind speeds in major jet streak features propagating about intense extratropical cyclones. In addition, in situ data were incorrectly assimilated and tropical cyclones were poorly resolved. In this study an intensive kinematic reanalysis was carried out in which wind fields in extratropical storms were intensified as necessary, in situ surface wind data were correctly reassimilated, and tropical cyclone boundary layer winds were included. Comparisons with in situ buoy measurements and satellite altimeter data show clear improvements in both bias and scatter in the wave hindcasts using the kinematically reanalyzed wind fields, particularly in the higher sea states. Furthermore, the hindcast wind and wave climatologies closely resemble those obtained from measured wind and wave data from buoys and offshore platforms.