Annual report 2005-06.indd - Antarctic Climate and Ecosystems ...

climate variability & changeCVC-04: Simulation of iceocean-atmosphereinteractionand climateProject leaderNathan Bindoff, UTAS/CMARProject staffS Marsland, R Murray, ACE; T Hirst, S O’Farrell,CMAR; J Roberts, TPAC; P Heil, G Hyland, RWarner, AAD; N Adams, S Pendlebury, P Reid,BoM; O Alves, N Smith, F Tseitkin, BMRC; PPetrelli, University of Sienna (Italy)Project AimSeasonal and decadal variations and long termtrends in Southern Ocean water masses (e.g., intemperature, salinity, currents, etc.) are poorlyunderstood at present. We are researching theprocesses that are central to understandingclimate variability near Australia and Antarctica,and are also involved in activities related to theforecasting of sea ice motion.We are using numerical simulations of theSouthern Ocean and its components, which aretested and validated against observational datafrom the other ACE CRC research programs. Thisallows us to diagnose the important processesacting in the Southern Ocean that both influenceand respond to global and regional climate. Theenhanced climate models resulting from thisresearch will deliver more reliable projections ofclimate variability and change and their impacts.• A new set of climate scenarios have beenrun with the CSIRO Mk3.5, which has animproved ACC and stratification in SouthernOcean. Analyses of these results areunderway.• The variability of the sea ice in the Mk3.0and Mk3.5 models has been analysed withstrengths of links with El Niño SouthernOscillation (ENSO), Southern Annular Mode(SAM) and Southern Ocean overturning ineach sector calculated.• The digital library on the national APAC gridhas been released. The library has beenaugmented with key ACE CRC data, includingArgo data, new altimetry products, Modiscolour simulations, IPCC model simulations,ACE high resolution model simulations,and enhanced search and browse facilities.Most of these data are central to ACE CRCdeliverables, and being used across theACE CRC programs. We have completed arobust web crawler for OpenDAP sites thatscales to data sets that includes millions offiles. Twenty-five Terabytes are now undermanagement across Australia.• Technical improvements have been madein grid design for numerical models and inparticular for the AusCOM model.• New results are emerging on the changes ofwater mass distributions, ocean ventilationand subduction rates and ocean stratificationfrom IPCC class models. These model resultshave a high degree of correspondence to theresults from the observational program.Key achievements in 2005-06• Assessment of sensitivity of Adélie LandBottom Water Formation in response tochanged atmospheric conditions in theclimate system has been completed and isundergoing revision.• The variations in the Indian Ocean at 32°Shave now been explained in terms of theprocesses of ocean advection and sea surfacetemperature changes. These processes in thisregion agree with the mechanisms of Bindoffand McDougall (2001).• New model analyses show that the meanocean flow is highly correlated to eddygeneration. Most significant heat transportby eddies is north of the Sub-Antarctic Frontassociated with the Agulhas retroflection.24 Antarctic Climate & Ecosystems CRC - Annual Report 2005-06