Thin Ice Thickness Measured by Upward-Looking Sonar in a Marginal Sea

摘要

Upward-looking sonar (ULS) has been used successfully to observe icernthickness in polar regions since the 1990s, but studies of applying ULSrnto the measurement of thin ice are rare. In the 2003/2004 winter, a ULSrnwas deployed to measure ice thickness at an oil platform in Bohai Sea.rnThe data, with a relatively high sampling frequency, were transmittedrnthrough a cable from the observation system and stored in a computerrnset on the platform and also sent to a remote computer in real time. Arnpractical model to derive the thickness of thin ice in the marginal icernzones is developed. In the Bohai Sea, the tide is one of the significantrnhydrodynamic features. The role of tide in affecting the residual totalrnerror in the determined mean ice thickness is discussed. The results ofrnsea ice thicknesses derived with the model were compared tornobservations and estimates from analysis of digital camera images. Thernmodel shows reasonable skill in detecting ice less than 0.5 m thick.