Numerical modelling and land-atmosphere feedback of drought in southeast Australia

Albedo and vegetation fraction play important roles in land-atmosphere interactions and local climate change. In this paper, the influence of these land surface parameters on the evolution of the drought that occurred in southeastern Australia between 2000 and 2008 is investigated. To examine the impact of variable land surface conditions on the hydrometeorology of the region, the Weather Research and Forecasting (WRF) model was used to perform a twin-study under two distinct scenarios. In the first instance, WRF was run in control mode with the default climatological surface albedo and vegetation fraction data sets. Then, these key surface variables were run in experiment mode with data sets derived from available satellite data. Comparison of these simulations demonstrates the importance of capturing the dynamic nature of land surface fields as the climate moves into, and then out of, a persistent multi-year drought. Both simulations capture the drought reasonably well, emphasizing changes in the large-scale circulation as a primary cause. Differences in the surface conditions do, however, provide local influence on the intensity and severity of drought.