Daily Surface Wind Fields Produced by Merged Satellite Data

Abstract

Scatterometers and radiometers on several polar-orbiting satellites routinely produce oceanic surface wind field data. For this study, we merged the NASA scatterometer (NSCAT) data with scatterometer data from the European Remote Sensing (ERS) satellite 2, and the wind speeds from two of the Special Sensor Microwave/Imagers (SSM/I) and produced daily 1° latitude by 1° longitude gridded wind fields over the global ocean for September 1996 through June 1997. This time period coincides with the lifetime of the NSCAT aboard ADEOS-1. We created these wind fields by utilizing the Kriging technique with its associated variograms, which consider both space and time wind vector structures. The resulting daily wind fields, when compared with moored-buoy wind speed and direction measurements, resulted in a root-mean-square (rms) difference of less than 1.5 m/s. No significant difference was found between statistical parameters estimated over the equatorial zone and middle latitudes. To investigate the global patterns of these new satellite wind fields, comparisons with the National Environmental Prediction Center's (NCEP) re-analysis products have been carried out. The satellite data and the NCEP products have a similar statistical error structure, but the merged wind fields provide complete coverage at much higher spatial resolution. Accurate surface wind speed estimates are an important factor in determining the velocity and magnitude of air-sea gas exchange.