A New FSU Winds and Flux Climatology

An objective technique is used to create a new monthly climatology for surface fluxes and related fields. The wind (pseudostress) products are improvements over the subjectively analyzed FSU winds. Fields of turbulent surfaces fluxes and the variables needed to calculate these fluxes are also generated. The fields are created through minimization of a cost function, which maximizes information from the observational data and minimizes smoothing. This approach ensures internal consistency between the turbulent fluxes and the related fields. Two products are produced: one based solely on in-situ observations, and another that also includes scatterometer observations. Comparisons are made between the new FSU fields (based on volunteer observing ships and buoy observations), the old subjective FSU fields, individual TAO buoys, the DaSilva climatology (the background for the objective technique), the NCEP reanalysis, and fields based solely on the SeaWinds scatterometer observations.

The objective technique treats various types of data sources (volunteer observing ships, buoys, and scatterometers) as independent. Weights related to each type of data and to penalty functions are objectively determined through cross validation. These weights are applied to constraints in the cost function. Three types of constraints are applied to each vector variable: misfits to each type of observation, a smoothing term, and a misfit of curl. The second and third terms are relative to a background field. The first two types of constraints are applied to scalar terms. The influence of the background field, relative to the observations, is controlled by the ratio of the weight for misfit to observations to the weights on the smoothing constraints. The background field is the DaSilva climatology.