Comparisons of monthly mean 10 m wind speeds from satellites and NWP products over the global ocean

The accuracy of wind speed at 10 m above the sea surface from two satellite and three numerical weather prediction (NWP) products is investigated over the global ocean. Rain-free equivalent neutral winds from the Quick Scatterometer (QuikSCAT) are converted to stability-dependent winds to be consistent with those from NWP products and are taken as truth in comparisons to winds from other products. Quantitative statistical analyses presented at each grid point over the global ocean reveal that monthly winds from NWP products have almost perfect skill relative to those from QuikSCAT winds during the 3-year common period (September 1999 to August 2002). Exceptions occur in tropical regions and high southern latitudes. Wind speeds adjusted to 10 m at many moored buoys located in different regions of the global ocean further confirm the accuracy of monthly NWP winds, giving RMS difference of 1.0 m s(-1) based on 1281 monthlong time series. The satellite-based QuikSCAT winds agree with buoy winds relatively better than NWP products. While there is good agreement among wind products on monthly timescales, large differences (>3 m s(-1) and more) in NWP winds are found in comparison to QuikSCAT winds on shorter time intervals at high latitudes. Daily means of sensible and latent heat fluxes based on NWP winds can therefore differ as much as 100 W m(-2) in comparison to those based on QuikSCAT winds. In general, NWP wind-based sensible and latent heat fluxes are more similar to their QuikSCAT wind-based counterparts in tropical regions and midlatitudes.