The CSIRO Mk3L climate system model v1.0 coupled to the CABLE land surface scheme v1.4b: evaluation of the control climatology

J Mao,B Pak,Y P Wang,A J Pitman,G Abramowitz,S J Phipps

doi:10.5194/gmd-4-1115-2011

Abstract

Abstract. The CSIRO Mk3L climate system model, a reduced-resolution coupled general circulation model, has previously been described in this journal. The model is configured for millennium scale or multiple century scale simulations. This paper reports the impact of replacing the relatively simple land surface scheme that is the default parameterisation in Mk3L with a sophisticated land surface model that simulates the terrestrial energy, water and carbon balance in a physically and biologically consistent way. An evaluation of the new model's near-surface climatology highlights strengths and weaknesses, but overall the atmospheric variables, including the near-surface air temperature and precipitation, are simulated well. The impact of the more sophisticated land surface model on existing variables is relatively small, but generally positive. More significantly, the new land surface scheme allows an examination of surface carbon-related quantities including net primary productivity which adds significantly to the capacity of Mk3L. Overall, results demonstrate that this reduced-resolution climate model is a good foundation for exploring long time scale phenomena. The addition of the more sophisticated land surface model enables an exploration of important Earth System questions including land cover change and abrupt changes in terrestrial carbon storage.

Highlights

There is a need for a hierarchy of climate models ranging from the fully-coupled climate system models integrated at the highest spatial resolution possible, through to heavily parameterised models that resolve spatial resolution in one dimension (McAvaney et al, 2001)
In terms of terrestrial quantities, we evaluate Community Atmosphere Biosphere Land Exchange (CABLE) using several estimates for net primary productivity: a MODIS product (Zhao et al, 2005), monthly net primary productivity from the Carnegie-AmesStanford Approach (CASA) model (Potter et al, 1993; Randerson et al, 1997) and a multi-model mean net primary productivity from Cramer et al (1999)
This paper has evaluated the atmosphere-sea ice-land surface component of the Commonwealth Scientific and Industrial Research Organisation (CSIRO) Mk3L climate system model version 1.0, and has shown that it performs on a par with those models used in the 3rd Assessment Report of the Intergovernmental Panel on Climate Change

Summary

Introduction

There is a need for a hierarchy of climate models ranging from the fully-coupled climate system models integrated at the highest spatial resolution possible, through to heavily parameterised models that resolve spatial resolution in one dimension (McAvaney et al, 2001). This paper describes and evaluates an upgraded version of the Commonwealth Scientific and Industrial Research Organisation (CSIRO) Mark 3 reduced-resolution model (Mk3L; Phipps et al, 2011). This model is not a “state-ofthe-art” climate system model because several parameterisations, and the model resolution, are chosen for computational efficiency. Mk3L is best described as a reduced-resolution climate model; its parameterisation and resolution would have been state-of-the-art for the Second Assessment Report of the IPCC (Houghton et al, 1996) in that the model contains some sophisticated physics (in particular terrestrial processes), as well as relatively complex representations of sea ice, ocean and atmospheric processes

Objectives

Results

Conclusion