Variableness of the Sound Velocity Profile About the Mid-Atlantic Ridge Axis

摘要

Mediterranean Water, spreading across the North Atlantic Ocean, is shown to cause a disturbance to the acoustic medium in the vicinity of the Mid-Atlantic Ridge north of the Azores. In this region, the ridge crests are sufficiently shallow so as to impede the free movement of the intermediate waters. Warm and saline layers, nearly two hundred meters thick, were repeatedly observed in the lowering of continuous sampling sensors. These inversion layers are shown, by reconstruction, to result from local water movement across the ridge crest and are argued to be short lived and spatially confined. As a direct consequence the observed depth of the sound velocity minimum unpredictably fluctuated as much as five hundred meters within an area of two hundred miles square. The layers themselves result in secondary sound channels. The inversions of both temperature and salinity combine to produce inversions in the sound velocity profile of four meters per second, deep in the thermocline. (Author)