Configuration and spin-up of ACCESS-CM2, the new generation Australian Community Climate and Earth System Simulator Coupled Model

• Published in: Journal of Southern Hemisphere Earth Systems Science
• Main Authors: Bi, D, Dix, M, Marsland, S, O'Farrell, S, Sullivan, A, Bodman, R, Law, R, Harman, I, Srbinovsky, J, Rashid, HA, Dobrohotoff, P, Mackallah, C, Yan, H, Hirst, A, Savita, A, Boeira Dias, F, Woodhouse, M, Fiedler, R, Heerdegen, A
• Format: Article in Journal/Newspaper
• Language: English
• Published: CSIRO Publishing 2020
• Subjects: Earth Sciences; Climate change science; Climatology; Antarctic; Southern Ocean; The Antarctic; Antarc*; Sea ice
• Online Access: https://doi.org/10.1071/ES19040; http://ecite.utas.edu.au/143769

A new version of the Australian Community Climate and Earth System Simulator coupled model, ACCESS-CM2, has been developed for a wide range of climate modelling research and applications. In particular, ACCESS-CM2 is one of Australias contributions to the World Climate Research Programmes Coupled Model Intercomparison Project Phase 6 (CMIP6). Compared with the ACCESS1.3 model used for our CMIP5 submission, all model components have been upgraded as well as the coupling framework (OASIS3-MCT) and experiment control system (Rose/Cylc). The component models are: UM10.6 GA7.1 for the atmosphere, CABLE2.5 for the land surface, MOM5 for the ocean, and CICE5.1.2 for the sea ice. This paper describes the model configuration of ACCESS-CM2, documents the experimental set up, and assesses the model performance for the preindustrial spin-up simulation in comparison against (reconstructed) observations and ACCESS1.3 results. While the performance of the two generations of the ACCESS coupled model is largely comparable, ACCESS-CM2 shows better global hydrological balance, more realistic ocean water properties (in terms of spatial distribution) and meridional overturning circulation in the Southern Ocean but a poorer simulation of the Antarctic sea ice and a larger energy imbalance at the top of atmosphere. This energy imbalance reflects a noticeable warming trend of the global ocean over the spin-up period.