Measurement of Fluctuations in the Tilt of Arctic Ice at the Cearex Oceanography Camp: Experiment Review, Data Catalog and Preliminary Results

• Main Authors: Czipott, Peter V., Podney, Walter N.
• Other Authors: PHYSICAL DYNAMICS INC LA JOLLA CA
• Format: Text
• Language: English
• Published: 1989
• Subjects: Physical and Dynamic Oceanography; Snow; Ice and Permafrost; *OCEAN WAVES; *SEA ICE; MEASUREMENT; PEAK VALUES; TEMPERATURE; WIND; COHERENCE; MOTION; STRAIN(MECHANICS); RUPTURE; VARIATIONS; SPECTRA; ICE; GUSTS; SPECTRAL ENERGY DISTRIBUTION; CATALOGS; OSCILLATION; RIGIDITY; SPECTRUM ANALYSIS; FLEXURAL PROPERTIES; TILT; INTERNAL WAVES; OPEN WATER; ARCTIC REGIONS; WAVE PACKETS; EAST(DIRECTION); OCEANOGRAPHY; BEAUFORT SEA; PACK ICE; TILTMETERS; COMPRESSION; FREQUENCY; CEAREX; ICE TILT; ICE MECHANICS; SWELLS(OCEAN WAVES); Arctic; Arctic Ocean; Yermak Plateau; Beaufort Sea; Ice; ice pack; permafrost; Sea ice; Yermak plateau
• Online Access: http://www.dtic.mil/docs/citations/ADA215059; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA215059

Three tiltmeters set in a triangular array on the eastern Arctic Ocean near 83 deg. N, 10 deg E produced high quality data 30 Mar - 19 Apr 89, as part of the Coordinated Eastern Arctic Experiment (CEAREX). Spectra of tilt fluctuations show the same features as those from the Arctic Internal Wave Experiment (AIWEX), recorded Apr 85 on the Beaufort Sea near 74 deg N, 145 deg W. They show a spectral peak centered near a period of 40 seconds, which results from a long period swell coming from open seas, together with a sharp rise in spectral density below a frequency of several cycles per hour, which comes from internal waves. A pronounced spectral valley or window, from about 2 mHz to 20 mHz, separates the two dominant features. In addition to quasi-stationary fluctuations that give the dominant spectral features, the data reveal three kinds of intermittent activity: 1) solitary internal waves emanating from the direction of the Yermak Plateau; 2) seismic-like signals coming from ice rupture; and 3) rapid oscillations with periods of a few seconds, lasting for tens of minutes, that possibly arise from rigid oscillations of an ice floe driven by wind gusts. Fluctuations in tilt are highly coherent with in situ temperature fluctuations that come from a solitary internal wave packet, but fluctuations in strain show little coherence. Because tilt results predominantly from ice flexure and strain mainly from ice compression, internal waves probably drive only flexural waves in the ice. Compressional noise dominates ice strain at internal wave frequencies, originating perhaps from differential motions of the ice pack. (edc)