A laboratory study of friction-velocity estimates from scatterometry: low and high regimes

Both wind and rain roughen the sea surface, but whereas wind generates waves, rain generates craters, stalks and ring-waves. Average backscat tered power for scatterometer returns from water surfaces is closely related to small scale features on the water surface, so we use backscattered power from short wind-waves as a basis to evaluate the importance of ring-waves. Experi ments were conducted with a 13•5 GHz scatterometer (30° incidence angle, vertical polarization) in a wind-wave tank that is enhanced by a rain simulator. Rain intensities ranged from 3-30 mm h-1 and wind friction velocities were between 10 and 50 cm s • 1• The variance of surface elevation for small scale features �;m, i.e., ring-waves and short wind-waves, was computed for each case using data from a capacitance probe. Comparison of the data sets shows that the range of �;m for the rain cases is comparable to that from light to moderate wind cases-so ring-wave amplitudes are not negligible. Analysis of the radar data provides evidence that ring-waves are the dominant feature contributing to the backscattered power. Thus ring-waves need to be included in scatterometer numerical models that contain rain effects.

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Presenting the Rain-Sea Interaction Facility

Bliven

Elfouhaily²

Proceedings of IGARSS '94 - 1994 IEEE International Geoscience and Remote Sensing Symposium

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A laboratory study of friction-velocity estimates from scatterometry: low and high regimes

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References 20 publications

Determination of the geophysical model function of NSCAT and its corresponding variance by the use of neural networks

Determination of the geophysical model function of NSCAT and its corresponding variance by the use of neural networks

An analysis of scatterometer returns from a water surface agitated by artificial rain: evidence that ring-waves are the main feature

Presenting the Rain-Sea Interaction Facility

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