Characteristics of the Sea Ice Drift Caused by Wind Action on the Northeastern Shelf of Sakhalin Island

摘要

The research analyzes synchronous hourly series of the wind speed vectors and the ice drift vectors that were measured in 1992 and 1993 by radar units located on the northeastern coast of Sakhalin. The analysis shows that, on the shelf, the ice response to external influence differs considerably from the response in the open ocean as a result of sharp changes in the sea depth and presence of the coastal boundary. In particular, the values of the wind coefficient and the drift angle depend on the wind direction. In order to characterize the wind drift in the coastal zone, we applied a two-dimensional regression model that may explain from 60 to 80% (depending on the calculation variant) of the drift dispersion. The calculations were performed for each station both by months and for the whole ice period. The wind coefficients are determined with the ellipsis constructed of the unit circle after the matrix transformation has been applied. These ellipses are oriented north-northwest-south-southeast and are squeezed. Hence, we conclude that there exist "efficient" directions of the wind with the maximum wind coefficient (～4-7%) and "inefficient" (1%) directions. The drift turn happens clockwise for wind directions that are close to the zonal one and counterclockwise for meridianal (going along the coast) directions. We also defined eigendirections with zero drift angle, that is, such wind directions that form the drift in the same direction without deviation. The stability of results obtained in different time periods at each station allows their practical application for operative and long-term forecast of the ice load on structures of the oil and gas complex on the northeastern shelf of Sakhalin Island.