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: Daohua, Bi, Dix, Martin R, Marsland, S J, O'Farrell, S P, Sullivan, Arnold, Bodman, Roger, Law, Rachel, Harman, Ian, Srbinovsky, Jhan, Rashid, Harun A, Heerdegen, Aidan
• Format: Article in Journal/Newspaper
• Language: English
• Published: CSIRO Publishing 2023
• Subjects: ACCESS-CM2; climate change; climate simulation; CMIP6; coupled climate model; evaluation; green house gases; physical configuration; preindustrial spin-up; tuning and debugging; Antarctic; Southern Ocean; The Antarctic; Antarc*; Sea ice
• Online Access: http://hdl.handle.net/1885/303295; https://doi.org/10.1071/ES19040; https://openresearch-repository.anu.edu.au/bitstream/1885/303295/3/TMP48586764820231016102347.pdf.jpg

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. This project is jointly funded through CSIRO and the Earth Systems and Climate Change Hub of the Australian Government’s National Environmental Science Program.