An Assessment of GEOS-3 Wave Height Measurements
An iterative technique has been developed for the fitting of an averaged narrow-pulse radar altimeter return waveform from the Geodynamics Experimental Ocean Satellite (GEOS-3) with a four-parameter function derived from fundamental microwave rough scattering theory. For a signal reflected from the earth’s oceans, the parameter associated with the slope of the leading edge of this waveform is directly relatable to the significant wave height of the sea. The technique was used during February 1976 when an intensive effort was made to map the sea state of the North Atlantic Ocean for comparison with several forms of truth information. Underflights of GEOS-3 orbits were made by a NASA C-54 aircraft with other narrow pulse radar systems, and shipboard observations of the significant wave height were received from four European-staffed Ocean Weather Stations. More recently, comparisons of GEOS-3 measurements with NOAA Data Buoy Office data in the GuZf of Alaska have also been made. Excellent agreement exists between the aircraft remote sensor data, the buoy data, and the GEOS-3 measurements if the effect of tracking jitter is included in the GEOS-3 data processing. The average difference between the GEOS-3 measurements and the corresponding comparison data set values is shown to be.34 m with a standard deviation of the differences of.61 m. The agreement between satellite and Ocean Weather Ship data is not as good. The presence of systematic biases in the shipboard observations is suggested.
KeywordsWave Height Significant Wave Height Naval Research Laboratory Radar Altimeter Return Waveform
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