Remote Sensing Of The Air-Sea Interface Using Microware Acoustics

Abstract

Measurements of sea surface acoustic backscatter and ambient noise at centimeter wavelengths have been taken over the past several years in the open ocean, Dabob Bay, and Lake Washington. These measurements were taken to characterize undersea reverberation and background noise as a function of geometry (e.g., grazing angle), frequency, and environmental conditions. The environmental conditions measured were principally wind speed and large-scale wave height, although the most recent measurements, taken in the lake, were significantly more comprehensive. From these measurements, which were originally intended to determine the underwater acoustic environment at high frequencies, it was evident that the problem could be inverted and the acoustic measurements used to infer environmental parameters at the air-sea interface. For example, the ambient noise level and the backscattering strength at low to moderate grazing angles could be used to infer wind speed and wind stress. Based on the data taken by this author and others, an acoustic remote sensing system is suggested along with the environmental measurements that should be taken to test the viability of this system.