Impact of varying the complexity of the land surface energy balance on the sensitivity of the Australian climate to increasing carbon dioxide

Climate Research

A. J. Pitman¹  B. J. McAvaney¹ 

关键词: Surface energy balance;    Land surface models;    Climate changes;    Land surface complexity;    Australian climate;    Climate modelling;   

DOI  :  10.3354/cr025191

来源: Inter-Research Science Publishing

【 摘 要 】

ABSTRACT: This study explores whether regional climate model scenarios are sensitive to uncertainty inthe representation of surface energy balance (SEB) complexity. Simulations with the Bureau of Meteorology Research Centre climate model and theCHAmeleon Surface Model (CHASM) were used to explore the sensitivity of changes in air temperature (T), evaporation (E), precipitation (P) and soil moisture (W) over Australia resulting from a doubling of atmospheric carbon dioxide (ΔCO₂).The 1 × CO₂ and the 2 × CO₂ simulations of T, E, P and W were sensitive to the complexity of the SEB, even though the grand mean of these quantities was almost always insensitive to SEB complexity. Seasonal variations inT, E, P and W at 1 × CO₂ and 2 × CO₂ were sensitive in terms of the point-by-point temporal mean and temporal variance. The overall spatial and temporal variances of T and P were insensitive to SEB complexity, but E and Wwere sensitive during periods of drying. The simulated seasonal change in T, E, P and W was insensitive to the SEB, and uncertainty in SEB parameterisation does not limit the reliability of existing climate change scenarios for Australia. However, thetemporal variance of E, P and W was sensitive to the SEB complexity during periods of drying. Use of temporal variances of these quantities in future impact assessments are therefore likely to be very limited until uncertainty in the representation of SEBin climate models is reduced. To simulate the climate over Australia at either 1 × CO₂ or 2 × CO₂, a reasonably complex representation of the SEB, including a temporally and spatially variable surface resistance and anexplicit representation of canopy interception, is required. Finally, our results say nothing about the importance of the land surface in general, since our analysis is restricted to a consideration of the SEB alone.

【 授权许可】

Unknown