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

• Main Authors: Aidan Heerdegen, Russell Fiedler, Matthew Woodhouse, Fabio Boeira Dias, Abhishek Savita, Anthony Hirst, Hailin Yan, Chloe Mackallah, Peter Dobrohotoff, Harun A. Rashid, Jhan Srbinovsky, Ian Harman, Rachel Law, Roger Bodman, Arnold Sullivan, Siobhan O'Farrell, Simon Marsland, Martin Dix, Daohua Bi
• Format: Article in Journal/Newspaper
• Language: English
• Published: CSIRO Publishing 2020
• Subjects: ACCESS-CM2; climate change; climate simulation; CMIP6; coupled climate model; evaluation; Meteorology. Climatology; QC851-999; Environmental sciences; GE1-350; Antarctic; Southern Ocean; The Antarctic; Antarc*; Sea ice
• Online Access: https://doaj.org/article/2e23480a5ce443d091dfb28f4f9d7b0f

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 Australia's contributions to the World Climate Research Programme's 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.