10/01/2012
Evaluation of Surface Flux Parameterizations
Summary
U.S. Department of Energy (DOE) scientists used a seven-year dataset from the Atmospheric Radiation Measurement (ARM) scientific user facility’s Southern Great Plains site to evaluate the six surface flux parameterizations used in the Weather Research and Forecasting (WRF) model and three U. S. global climate models (GCMs). Surface momentum, sensible heat flux, and latent heat flux are critical processes that need to be accurately represented in large-scale weather and climate models. However, direct observational evaluation of the parameterization schemes for these fluxes is rare. The long-term observations of surface fluxes collected at the ARM Southern Great Plains site were used to evaluate the model parameterizations under a variety of stability conditions, diurnal cycles, and seasons. Statistical analyses show that the momentum flux parameterization agrees best with the observations, followed by latent heat flux, sensible heat flux, and the evaporation ratio/Bowen ratio. The overall performance of these parameterizations depends on atmospheric stability and is best under neutral stratification conditions, deteriorating under both more stable and more unstable conditions. The results also demonstrate the need for improving land-surface models and for the measurement of surface properties that allow their full evaluation.
References
Liu, G., Y. Liu, and S. Endo. 2012. “Evaluation of Surface Flux Parameterizations with Long-Term ARM Observations,” Monthly Weather Review, DOI: 10.1175/MWR-D-12-00095.1.