Comparison of turbulence closure schemes in the simulation of terrain-disrupted airflow

The choice of turbulence parameterization scheme in a mesoscale numerical model would affect the forecast of low-level turbulence intensity in an area of complex terrain. This study extends the work of Chan (2006) to examine the simulation results of three schemes in the Regional Atmospheric Modelling System (RAMS), namely, the old schemes of Mellor and Yamada and Deardorff, and the new E-l scheme of Castelli et al. This is the first study of the comparison of the three schemes in the simulation of real cases. Deardorff scheme is found to perform the best in forecasting turbulence intensity, while the new E-l scheme captures the microscale features in the turbulent airflow.