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Downscaling the climate change for oceans around Australia


Chamberlain, MA and Sun, C and Matear, RJ and Feng, M and Phipps, SJ, Downscaling the climate change for oceans around Australia, Geoscientific Model Development, 5 pp. 1177-1194. ISSN 1991-959X (2012) [Refereed Article]


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Copyright 2012 The Authors Licensed under Creative Commons Attribution 3.0 Unported

DOI: doi:10.5194/gmd-5-1177-2012


At present, global climate models used to project changes in climate poorly resolve mesoscale ocean features such as boundary currents and eddies. These missing features may be important to realistically project the marine impacts of climate change. Here we present a framework for dynamically downscaling coarse climate change projections utilising a near-global ocean model that resolves these features in the Australasian region, with coarser resolution elsewhere.

A time-slice projection for a 2060s ocean was obtained by adding climate change anomalies to initial conditions and surface fluxes of a near-global eddy-resolving ocean model. Climate change anomalies are derived from the differences between present and projected climates from a coarse global climate model. These anomalies are added to observed fields, thereby reducing the effect of model bias from the climate model.

The downscaling model used here is ocean-only and does not include the effects that changes in the ocean state will have on the atmosphere and air–sea fluxes. We use restoring of the sea surface temperature and salinity to approximate real-ocean feedback on heat flux and to keep the salinity stable. Extra experiments with different feedback parameterisations are run to test the sensitivity of the projection. Consistent spatial differences emerge in sea surface temperature, salinity, stratification and transport between the downscaled projections and those of the climate model. Also, the spatial differences become established rapidly (< 3 yr), indicating the importance of mesoscale resolution. However, the differences in the magnitude of the difference between experiments show that feedback of the ocean onto the air–sea fluxes is still important in determining the state of the ocean in these projections.

Until such a time when it is feasible to regularly run a global climate model with eddy resolution, our framework for ocean climate change downscaling provides an attractive way to explore the response of mesoscale ocean features with climate change and their effect on the broader ocean.

Item Details

Item Type:Refereed Article
Keywords:climate models, climate change, downscaling, oceans, Australia
Research Division:Earth Sciences
Research Group:Climate change science
Research Field:Climate change processes
Objective Division:Environmental Policy, Climate Change and Natural Hazards
Objective Group:Understanding climate change
Objective Field:Climate change models
UTAS Author:Phipps, SJ (Dr Steven Phipps)
ID Code:104717
Year Published:2012
Web of Science® Times Cited:18
Deposited By:IMAS Research and Education Centre
Deposited On:2015-11-18
Last Modified:2017-10-30
Downloads:167 View Download Statistics

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