HR: 0800h
AN: OS41B-0602    [Abstracts]
TI: Invisible component of deep convection
AU: Pisarevskaya, L G
EM:
AF: Tectonics Special Research Centre, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 Australia
AU: * Pisarevsky, S A
EM: spisarevsky@tsrc.uwa.edu.au
AF: Tectonics Special Research Centre, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 Australia
AB: Measurements of vertical distribution of temperature and salinity near icebergs and in the ice marginal zone of the Barents sea show that far below the supposed ice keels happens mixing of the cold water with the warm saline Atlantic water. Icebergs contain air-bubbles (up to 15% of volume) and sediments (up to 40%). A simple one-dimensional model is presented that considers upward buoyancy of melt water and air bubbles and downward buoyancy of sediments and cooled ambient water. Estimates for maximum distance of ascending and descending plumes as well as volume fluxes are derived from the melt rate and ambient water stratification characteristics. Similarly to the air bubbles that still continue their way to sea surface after plume of mixed water sheds some fluid at neutral buoyancy level(s), it is supposed that sediments continue their way to the sea bottom transporting and depositing mixed fluid far below picnocline. To compensate vertically diverging flows, a horizontal current into the region is formed. This triple current system is consistent with Petterson's experiments in a laboratory tank performed in 1907 to explain the ocean currents system. To obtain open-ocean deep convection one needs just a group of sediment-laden icebergs or ice floes melting in warm surface water: the surface water will be carried a bit into and mixed with the cold underlying layer, and the water of cold one into and mixed with the next -warm Atlantic water to form a well-described chimney structure. To compensate diverging vertical flows a horizontal influx into the region will form, that will be governed by glaciation's relief and underlying bedrock.
DE: 4203 Analytical modeling and laboratory experiments
DE: 4207 Arctic and Antarctic oceanography (9310, 9315)
DE: 4540 Ice mechanics and air/sea/ice exchange processes (0700, 0750, 0752, 0754)
SC: Ocean Sciences [OS]
MN: Fall Meeting 2005