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CSIRO Marine and Atmospheric Research
Past Seminars

Seminar Abstract

Antarctic coastal polynya response to climate change

Adelie Land Bottom Water is the major contributor to Antarctic Bottom Water (AABW) in the Australian Antarctic Basin. The main source is dense shelf waters formed in the Mertz Glacier Polynya (MGP).

A global setup of the Max Planck Institute Ocean Model with high horizontal resolution over East Antarctica is used to model interannual variability of shelf water formation in the MGP under NCEP-NCAR daily forcing for the 1990s. Two distinct phases of polynya activity are identified: characterised by strong or weak production and outflow of dense High Salinity Shelf Water (HSSW). We investigate the sensitivity of the HSSW formation during both the strong and weak polynya periods to perturbations of air temperature and precipitation expected under a global warming scenario. It is found that the production of HSSW decreases with both increasing air temperature and increasing precipitation.

The current generation of IPCC-class ocean and sea ice GCMs suggest a slowdown of Meridional Overturning Circulation (MOC) under global warming, but do not adequately resolve the Antarctic coastal water mass transformation processes. The implication of this study is that the Southern Ocean MOC will slow down. Further, other IPCC-class models will most likely show this response as there horizontal resolution is refined sufficiently to simulate the ocean and sea ice interactions in Antarctic coastal polynyas.

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CSIRO = Marine Laboratories Auditorium, Castray Esplanade, Hobart

For further information, or to schedule a seminar, contact:
Peter Oke, (Oceanographic seminars) CSIRO Marine Research (03) 6232 5387
Piers Dunstan, (Biological seminars) CSIRO Marine Research (03) 6232 5382
Katrina Nitschke, Antarctic Climate and Ecosystems CRC (03) 6226 2265 & IASOS, University of Tasmania (03) 6226 2509