ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

3aUW12. Acoustic measurements of ice cover variations in the Arctic Ocean.

Victor V. Artel

Mikhail A. Raevsky

Inst. of Appl. Phys., 46, Ulyanov St., 603600 Nizhny Novgorod, Russia

Climatic monitoring of the Arctic Ocean implies long-duration observations of the ice cover and water temperature variations by measuring the characteristics of low-frequency acoustical signals traveled along stationary paths. The sensitivity of sounding signal parameters to the variations of the ice cover characteristics is one of the important problems in climatic monitoring. The time structure of the pulse signal in the Arctic waveguide is investigated. The relative influence of the ice cover thickness, density, shear, and compressional sound speeds on the variations of the phase and time delay of the normal modes is studied. It is found that, in the frequency range f(less than or approximately equal to)30 Hz, the variations of the ice cover density and thickness are more efficient than sound-speed variations. Taking the desalination of the subsurface layer into account decreases ice thickness influence. These effects are compared with signal fluctuations in the Arctic Ocean. The fluctuations of the cw signal of the frequency f=20 Hz in the Arctic waveguide are investigated. The internal waves, the submesoscale eddies, and the ice cover drift are considered as signal fluctuations sources. According to the data of numerical simulation, the influence of submesoscale eddies is primary.

Standards Committee S2 on Mechanical Vibration and Shock. Working group chairs will present reports of their recent progress on writing and processing various shock and vibration standards. There will be a report on the interface of S2 activities with those of ISO/TC 108 (the Technical Advisory Group for ISO/TC 108 consists of members of S2, S3, and other persons not necessarily members of those committees) including a report on the activities of ISO/TC 108, including plans for its September 1996 meeting in Sydney, Australia. Scope of S2: Standards, specifications, methods of measurement and test, and terminology in the fields of mechanical vibration and shock, and condition monitoring and diagnostics of machines, but excluding those aspects which pertain to biological safety, tolerance, and comfort.