Evaluation of regional numerical weather prediction model surface fields over the Middle Atlantic Bight

Abstract

Coastal ocean models often rely on the surface fields from numerical weather prediction (NWP) models for realistic surface boundary conditions, but the errors in these fields are poorly understood. We evaluate the surface meteorological and flux fields provided by three of the regional NWP models in operation during 1996 and 1997 at the U.S. National Centers for Environmental Prediction (NCEP): the Eta‐48, Eta‐29, and Rapid Update Cycle (RUC‐1) models. These model fields are compared to in situ measurements made from an air‐sea interaction buoy deployed from July 1996 to June 1997 at a midshelf location in the Middle Atlantic Bight during the Coastal Mixing and Optics experiment. In addition, data from six National Data Buoy Center buoys are used to evaluate spatial errors in the model fields. The Eta‐29 and RUC‐1 models overestimate the net ocean‐to‐atmosphere heat flux by an average 83 and 74 W m−2, respectively, with notable errors in each of the individual heat flux components. The poorly resolved sea surface temperature fields used in the 1996–1997 regional NWP models lead to significant errors in the latent and sensible heat fluxes over the continental shelf and slope. Moreover, wind speeds are slightly overestimated in the Eta‐48 and Eta‐29 models while the RUC‐1 model underestimates them by more than 1 m s−1. All of the models have mean wind direction errors of 7° to 13° east of north. In light of these evaluations, considerations for improving the accuracy of the surface flux fields for use in future ocean modeling studies are discussed.