Vibrational Motion of Arctic Pack Ice

There are many physical mechanisms responsible for vibrations of sea, and they force motions in a very wide band of frequencies from less than 0.01 Hz to greater than 100 Hz. Detailed measurements of the vertical velocity in this frequency band were previously shown to be produced by gravity waves,...

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Bibliographic Details
Main Authors: Dugan, John, Morris, William, Williams, Zandy
Other Authors: ARETE ASSOCIATES ARLINGTON VA
Format: Text
Language:English
Published: 1997
Subjects:
Snow
Ice and Permafrost
Acoustics
*GEOACOUSTICS
*AMBIENT NOISE
*PACK ICE
VIBRATION
ELECTROMAGNETIC WAVE PROPAGATION
ICE FORMATION
UNDERWATER ACOUSTICS
GRAVITY WAVES
NOISE MODULATION
ICE BREAKUP
GEOPHONES
Arctic
Ice
permafrost
Online Access:http://www.dtic.mil/docs/citations/ADA329604
http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA329604
Description
Summary:There are many physical mechanisms responsible for vibrations of sea, and they force motions in a very wide band of frequencies from less than 0.01 Hz to greater than 100 Hz. Detailed measurements of the vertical velocity in this frequency band were previously shown to be produced by gravity waves, ridging events and wind turbulence. In this paper, higher frequency motions as measured by geophones for frequencies up to about 1 kHz have been analyzed, and the motions are identified as being generated by ridging events, thermal fracturing, and wind blown ice crystals. The sensors were frozen into the top surface of the ice, and they provided direct measurements of the vertical velocity that occurs in response to the different modes of waves that propagate away from these generation regions. The shape of the frequency spectrum is shown to be a strong function of the forcing mechanism, with the different ones being readily identifiable.

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