Journal cover Journal topic
Geoscientific Model Development An interactive open-access journal of the European Geosciences Union
doi:10.5194/gmdd-8-8063-2015
© Author(s) 2015. This work is distributed
under the Creative Commons Attribution 3.0 License.
Model description paper
18 Sep 2015
Review status
A revision of this discussion paper is under review for the journal Geoscientific Model Development (GMD).
The carbon cycle in the Australian Community Climate and Earth System Simulator (ACCESS-ESM1) – Part 1: Model description and pre-industrial simulation
R. M. Law1, T. Ziehn1, R. J. Matear2, A. Lenton2, M. A. Chamberlain2, L. E. Stevens1, Y. P. Wang1, J. Srbinovsky1, D. Bi1, H. Yan1, and P. F. Vohralik3 1CSIRO Oceans and Atmosphere, PMB 1, Aspendale, Victoria, Australia
2CSIRO Oceans and Atmosphere, Hobart, Tasmania, Australia
3CSIRO Manufacturing, Lindfield, New South Wales, Australia
Abstract. Earth System Models (ESMs) that incorporate carbon-climate feedbacks represent the present state of the art in climate modelling. Here, we describe the Australian Community Climate and Earth System Simulator (ACCESS)-ESM1 that combines existing ocean and land carbon models into the physical climate model to simulate exchanges of carbon between the land, atmosphere and ocean. The land carbon model can optionally include both nitrogen and phosphorous limitation on the land carbon uptake. The ocean carbon model simulates the evolution of nitrate, oxygen, dissolved inorganic carbon, alkalinity and iron with one class of phytoplankton and zooplankton. From two multi-centennial simulations of the pre-industrial period with different land carbon model configurations, we evaluate the equilibration of the carbon cycle and present the spatial and temporal variability in key carbon exchanges. For the land carbon cycle, leaf area index is simulated reasonably, and seasonal carbon exchange is well represented. Interannual variations of land carbon exchange are relatively large, driven by variability in precipitation and temperature. We find that the response of the ocean carbon cycle shows reasonable agreement with observations and very good agreement with existing Coupled Model Intercomparison Project (CMIP5) models. While our model over estimates surface nitrate values, the primary productivity agrees well with observations. Our analysis highlights some deficiencies inherent in the carbon models and where the carbon simulation is negatively impacted by known biases in the underlying physical model. We conclude the study with a brief discussion of key developments required to further improve the realism of our model simulation.

Citation: Law, R. M., Ziehn, T., Matear, R. J., Lenton, A., Chamberlain, M. A., Stevens, L. E., Wang, Y. P., Srbinovsky, J., Bi, D., Yan, H., and Vohralik, P. F.: The carbon cycle in the Australian Community Climate and Earth System Simulator (ACCESS-ESM1) – Part 1: Model description and pre-industrial simulation, Geosci. Model Dev. Discuss., 8, 8063-8116, doi:10.5194/gmdd-8-8063-2015, 2015.
R. M. Law et al.
R. M. Law et al.
R. M. Law et al.

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Short summary
The paper describes a version of the Australian Community Climate and Earth System Simulator that has been enabled to simulate the carbon cycle, which is designated ACCESS-ESM1. The model performance for pre-industrial conditions is assessed and land and ocean carbon fluxes are found to be simulated realistically.
The paper describes a version of the Australian Community Climate and Earth System Simulator...
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