Summertime maximum and minimum temperature coupling asymmetry over Australia determined using WRF.

Using the Weather and Research Forecasting model we derive the first estimates for intraseasonal soil moisture{atmosphere coupling strength for the Australian summer climate using methodology adapted from the Global Land-Atmosphere Coupling Experiment. We examine the variations in coupling strength by perturbing the background climate (dry vs. wet year) and the model physics (planetary boundary layer or cumulus scheme). For all choices of model physics, results identify Australia as a "hot spot" of soil moisture-atmosphere coupling for both mean and maximum temperature. For the wet case, results are consistent for maximum temperature for all physics choices. Results diverge more for maximum temperature in the chosen dry year. The coupling of soil moisture with minimum temperature is weaker but consistent for all choices of model physics or whether a wet or dry year is used. Coupling strength for precipitation is weak and not statistically significant irrespective of the choice of model physics.

Figure 1. Soil moisture-temperature coupling strength (CS) for WRF-LIS-CABLE for the different configurations. (a-d) for YSU PBL with KF cumulus scheme, (e-h) for YSU PBL with BMJ cumulus scheme, (i-l) for MYJ PBL with KF cumulus scheme and (m-p) for MYJ PBL with BMJ cumulus scheme. (1st column) TMAX CS for the dry soil moisture case, (2nd column)TMAX CS for the wet soil moisture case, (3rd column) TMIN CS for the dry soil moisture case and (4th column) TMIN CS for the wet soil moisture case. Regions that are statistically significant at the 90% level are stippled.