HR: 17:15h
AN: A14B-05    [Abstracts]
TI: Influence of Sea-ice on Inter-Annual Climate Variability in Coupled Ocean-Sea-ice-Atmosphere Simulations
AU: * Singarayer, J S
EM: joy.singarayer@bris.ac.uk
AF: University of Bristol, School of Geographical Sciences Bristol University University Road, Bristol, BS8 1SS United Kingdom
AU: Valdes, P J
EM: p.j.valdes@bris.ac.uk
AF: University of Bristol, School of Geographical Sciences Bristol University University Road, Bristol, BS8 1SS United Kingdom
AU: Bamber, J L
EM: j.bamber@bris.ac.uk
AF: University of Bristol, School of Geographical Sciences Bristol University University Road, Bristol, BS8 1SS United Kingdom
AB: There is currently considerable interest in the role of sea-ice on changes in climate and climate variability. Variations in sea-ice modify the atmosphere and oceans through its influence on albedo, ocean-atmosphere heat exchange and ocean buoyancy. Studies show clearly that interactions between sea-ice, oceans and atmosphere are likely to be important at seasonal to decadal timescales of variability. The interaction of Arctic sea-ice with Northern Hemisphere climate variability at these timescales has been investigated. The Hadley Centre ocean-atmosphere model, HadCM3, has been coupled to an elastic-viscous-plastic (EVP) sea-ice dynamics and Semnter zero-layer sea-ice thermodynamics schemes. Multi-decadal length simulations have been performed primarily using pre-industrial atmospheric forcing to determine natural variability and feedback processes inherent to the climate system. The simulations are examined in terms of patterns such as the North Atlantic Oscillation and oceanic thermohaline circulation, and how their characteristics and magnitude are influenced by key sea-ice processes, for example albedo feedbacks and brine rejection. The HadCM3 results using dynamic-thermodynamic sea-ice have also been compared to an equivalent simulation using thermodynamic sea-ice coupled to a simpler ice drift model in which sea-ice is passively advected using surface level ocean currents. By this comparison we investigate the effect of including wind-driven sea-ice motion on the mean climate and climate variability. Results suggest that extent and winter variability of Arctic sea-ice is improved. The sea-ice differences impact on high latitude temperatures and Arctic Oscillation pattern. The meridional overturning circulation becomes weaker as a result of increased ice export into the North Atlantic with a wind-driven sea-ice cover.
DE: 4215 Climate and interannual variability (3309)
DE: 4540 Ice mechanics and air/sea/ice exchange processes
DE: 1620 Climate dynamics (3309)
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting