Winter-time oceanography of the Adelie Depression

• Published in: Deep Sea Research Part II: Topical Studies in Oceanography
• Main Authors: Williams, GD, Bindoff, NL
• Format: Article in Journal/Newspaper
• Language: English
• Published: Pergamon-Elsevier Science Ltd 2003
• Subjects: Earth Sciences; Oceanography; Physical Oceanography; Adelie Depression; Antarctic; Commonwealth Bay; Mertz Glacier; Antarc*; Sea ice
• Online Access: https://doi.org/10.1016/S0967-0645(03)00074-2; http://ecite.utas.edu.au/34696

The formation of high-salinity shelf waters beneath coastal polynyas from enhanced sea-ice production and brine rejection during wintertime is critical to the production of Antarctic Bottom Waters. We report on the first wintertime measurements of high-salinity shelf water formation over the Adlie Depression off the East Antarctic coast between 143 and 146E, during the Mertz Glacier Polynya Experiment in July-August 1999. The general circulation and evolution of water masses in the Adlie Depression during winter are described, and in particular we quantify the rates of brine rejection (sea-ice growth), ocean heat flux, and latent heat flux, in the Mertz polynya central to the formation of high-salinity shelf waters. We find shelf waters above the minimum sill depth with sufficient density to become Adlie Land Bottom Water and suggest the highest production rates occur near Commonwealth Bay. Sea-ice growth and heat transfer rates are calculated from the divergence of heat and freshwater fields around a closed volume beneath the Mertz polynya. The sea-ice growth estimates and associated Monte Carlo errors are found to range from 4.81.7, 4.11.5, 8.41.7 cm d-1, respectively, over a 3-week period. The average growth rate is 5.8 cm d-1. Near the Mertz polynya the sensible heat from ocean transport is between 15 6 and 43 11 W m-2, with an average of 30 W m-2, and the latent heat budget is between 125 45 and 254 52 W m-2, with an average of 174 W m-2. We conclude that during winter the Mertz polynya is primarily a latent heat polynya. Crown Copyright 2003 Published by Elsevier Science Ltd. All rights reserved.