Thermohaline steps induced by melting of the Erebus Glacier tongue

• Main Authors: S. S. Jacobs, H. E. Huppert, G. Holdsworth, D. J. Drewry
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1981
• Subjects: Antarctic; The Antarctic; McMurdo Sound; Erebus Glacier; Erebus Glacier Tongue; Antarc*; Antarctica
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.694.7401; http://www.itg.cam.ac.uk/people/heh/Paper44.pdf

A vertically stable, step-like thermohaline structure is observed throughout a continuous, 400 m con-ductivity-temperature-depth (CTD) profile taken near the Erebus Glarer Tongue, McMurdo Sound, Antarctica. The pattern is best developed between the sea surface and 250 m depth, the interval corre-sponding to that of the irregular underwater profile of the Glacier Tongue. The steps average 17 m in thickness and typically display discontinuities of 0.1 øC in temperature, 0.04 %o in salinity and 3.5 x 10-4 g cm-3 in density. The observations are compared with theory and laboratory experiments of cell devel-opment and lateral flow near ice melting into vertically stratified salt water. At this location, subsurface seawater is inferred to remain above the in situ freezing point year-round, and contains sufficient heat to account for much of the Glacier Tongue thinning by basal melting. An adequate volume of meltwater would result to produce the measured salinity steps. We discuss related observations and some implica-tions of this process for ocean circulation and biological productivity in the Antarctic. OCEANOGRAPHIC OBSERVATIONS times the impact on density (o0 of a 0.1øC temperature In mid-February 1979 the U.S. Coast Guard icebreaker change. Temperature is n arly isothermal below 250 m, and Glacier occupied several stations in the southern part of more than 0.2øC above the in situ freezing point [Fujino et al., McMurdo S und (Figure 1), including three near the end of 1974] at all depths. Several of the station 217 steps can be