Source Size as a Theoretical Limitation on the Determination of Wave Vectors by Detector Arrays

Abstract

An important class of infrasonic waves in the atmosphere and seismic waves in the earth's crust are generated by ocean waves in marine storms. The determination of wave vectors from such large sources by detector arrays is limited by the systematic errors introduced by the large sources, as well as by the resolving power and ambiguities associated with any given array configuration. The apparent phase lag and coherency between two detectors, each receiving signals from the multitude of mutually incoherent oscillators comprising a large source, is discussed as a function of source size and source-detector configuration. It is found that the apparent phase lags between two detectors may deviate from the phase lag of a ray from the source center. As a result, the apparent phase lags among the detectors in an array may lead to an apparent wave vector discrepant with the wave vector from the source center. Empirical results are presented to confirm the validity of this approach in the case of microbarom generation by ocean waves.