Author(s): G. H. Leonard; C. R. Purdie; P. J. Langhorne; M. J. M. Williams; T. G. Haskell
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Keywords: No Keywords
Abstract: Ice crystals are observed floating freely in rivers, lakes, seas, and oceans in the cryospheric regions of both hemispheres. In the Southern Ocean their formation may be attributed to the presence of supercooled water, which is found on regional scales in certain locations off the Antarctic coast. During winter, ice crystals that nucleate in supercooled water created through basal melting of floating ice shelves can end up incorporated into adjacent sea ice sheets where they are termed” platelet ice”. One potential outcome of climate change is the warming of ice shelf cavity waters which may lead to enhanced basal melting and increased production of ice crystals, unless the adjacent waters are warmed to a point where they prevent the formation of supercooled water. Freely floating ice crystals are difficult to directly measure in situ due to the nature of their environment, particularly once an ice cover has formed at the ice-water interface. This paper reports on the use of backscatter readings from a Nortek 1 MHz Aquadopp ADCP deployed through a sea ice cover as a proxy for measuring ice crystals in the water column at a site adjacent to the McMurdo Ice Shelf, Antarctica during the austral winter of 2003. Ancillary measurements are used to assess its performance. An ADCP at a single frequency can detect the presence of freely floating ice crystals in the water column but is unable to estimate crystal sizes and concentrations.
Year: 2010