Variability and stability of Antarctic Bottom Water

Metadata record for data from ASAC Project 2535 See the link below for public details on this project. Project 2535 'Variability and stability of Antarctic Bottom Water (AABW)' Metadata description (1) Model analysis of natural AABW variability:- We have assessed the interannual to multi-decadal variability of AABW in a global coupled climate model, focussing on variations in bottom water formation rates, T-S changes on AABW neutral surfaces, and the physical mechanisms controlling this variability. The global coupled climate model used is the CSIRO Mark 3 Coupled Climate Model, which incorporates sub-models of the ocean, atmosphere, sea-ice, and land-surface. The experiments were run over a global grid at approximate resolution of 1.9 degrees x 1.9 degrees x 18 levels in the atmosphere, and 1.875 degrees x 0.94 degrees x 31 levels in the ocean. Variables analysed include oceanic temperature, salinity and circulation on AABW density layers, sea-ice extent and thickness, atmospheric sealevel pressure, temperature, and winds. The model integration considered was run with steady CO2 levels for two hundred years in a quasi-steady state mode. Full details of the CSIRO Mark 3 Coupled Climate Model can be found in Gordon et al. (2002). Gordon, H.B., Rotstayn, L.D., McGregor J.L., Dix M.R., Kowalczyk E.A., O'Farrell S.P., 2002: The CSIRO Mk3 Climate System Model. CSIRO Division of Atmospheric Research Technical Paper, No. 60. 130pp. (2) Model simulations of CO2-induced change in AABW: We also ran simulations of climate change within the Canadian University of Victoria Earth System Climate Model of Intermediate Complexity at a global longitude x latitude resolution of 3.6 degrees x 1.8 degrees. The model includes a primitive equation three-dimensional, 19 level ocean model, a sea-ice model, a simple land and river model and a two dimensional energy-moisture balance atmospheric model. A number of sensitivity experiments on ocean mixing parameters and the sea-ice model were conducted to optimise the Southern Hemisphere climatology for the control experiment. The control case (CTRL) was integrated for 3100 years starting from idealised initial conditions. Three climate change experiments were conducted, in which atmospheric carbon dioxide concentrations are changed to 450 ppm, 750 ppm and 1000 ppm from a pre-industrial level of 280 ppm, over different temporal regimes. Full model experiment descriptions appear in Bates, Sijp, and England (2005).