The land surface model component of ACCESS: description and impact on the simulated surface climatology

The land surface component of the Australian Community Climate and Earth System Simulator (ACCESS) is one difference between the two versions of ACCESS used to run simulations for the Coupled Model Intercomparison Project (CMIP5). The Met Office Surface Exchange Scheme (MOSES) and the Community Atmosphere Biosphere Land Exchange (CABLE) model are described and compared. The impact on the simulated present day land surface climatology is assessed, in both atmosphere only and coupled model cases. Analysis is focused on seasonal mean precipitation and screen-level temperature, both globally and for Australia. Many of the biases from observations are common across both ACCESS versions and both atmosphere only and coupled cases. Where the simulations from the two versions differ, the choice of land surface model is often only a small contributor with changes to the cloud simulation also important. Differences that can be traced to the land surface model include warm biases with CABLE due to underestimation of surface albedo, better timing of northern hemisphere snowmelt and smaller seasonal and diurnal temperature ranges with CABLE than MOSES.