Ice Thickness Distribution

Prototype Upward Looking Sonar (ULS) instruments that monitor time series of ice draft from oceanographic moorings have been designed, built, tested and deployed in arctic waters. The measured time series recovered from these instruments reveal many geophysically significant, quantitative aspects of the sea ice draft distribution that have not been measured or documented previously. The utility of the basic concept, and the soundness of the ULS Mark-1 design are confirmed by the data. Tests in the laboratory and in the field suggest opportunities for modest design changes that would improve the performance of the ULS. Proposed further work includes implementation of design modifications, detailed analysis of the ULS time series, redeployment of the prototype units, and construction and deployment of three new ULS units. Introduction and Background Approved for praisBte *•!«<»« [ DigtriiraÜasi Ualbnttod The geophysical study of sea ice requires that it be described in terms of a number of state variables. Using the equations of dynamics and thermodyanmics these variables are combined to describe the behavior of the ice and its interaction with the adjacent media of atmosphere and ocean. Given the complexity of sea ice on geophysical scales, it is crucial that these stat