Analysis of Sound Velocity Variation in an Estuary for NOS (National Ocean Service) Standards

摘要

Investigation of oceanographic data acquired in the Columbia River estuary, which lies the states of Washington and Oregon, revealed significant variation in sound velocity with respect to time and location. National Ocean Service (NOS) standards for echo-sounder acquired soundings require the knowledge of sound velocity to within plus or minus 4 meters per second. To meet this requirement in the Columbia River estuary, methods were devised to allow prediction of sound velocity based on location and the height of tide. Confidence intervals associated with sound velocity predictions provided by regression analyses showed a substantial improvement in accuracy when compared to using a single average velocity for each location. Nevertheless, there were still some cases where the NOS requirement could not be met. Keywords: Hydrography; Sound velocity variation; Estuary; Hydrographic surveying; Theses.