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<br />Studies by Ferguson (1967) have shown that wave disturbances acting <br /> <br />on a surface of discontinuity between two superimposed streams in an <br /> <br />incompressible fluid can be described by the following re'lationships: <br /> <br />.t:.Ps = <br /> <br />A ( _ V)2 <br />- u · coss <br />g <br /> <br />.t:.us = <br /> <br />A 2 <br />h (u . cosS - V) <br /> <br />where the amplitude of the surface variation, .t:.Ps, is related to <br /> <br />the amplitude A of the wave along the discontinuity, the angle <br /> <br />between propagation direction S and the mean wind in the layer u, <br /> <br />the phase velocity of the wave V, and the orbital wind spl:!ed .t:.us, <br />i.e., the amplitude of the surface wind speed during the passage of <br /> <br />the wave. Analysis of wave motion over the Great lakes produced <br />amplitudes of 655 m along a frontal surface. The wave length of <br />these gravity waves ranged from 55 to 185 km. Ferguson found that <br /> <br />the amplitude and wave length varied; however, the phase speed <br /> <br />remained nearly constant. He concluded that the wave effect on <br />convergence and vorticity may be signficant when the smal'l-scale <br /> <br />waves initiate long symmetric squall lines. <br /> <br />III. Remote Sensing From Surface Observation Systems <br /> <br />Radar and acoustical sounding measurements of gravity waves have <br /> <br />been made by Hicks (1969) and Gossard (1974) which show the gralvity <br /> <br />4 <br />