Implementation of a roughness sublayer parameterization in theWeather Research and Forecasting model (WRF version 3.7.1) and itsvalidation for regional climate simulations

Abstract. The roughness sublayer (RSL) is one compartment of the surface layer (SL) where turbulence deviates from Monin–Obukhov similarity theory. As the computing power increases, model grid sizes approach to the gray zone of turbulence in the energy containing range and the lowest model layer is located within the RLS. In this perspective, the RSL has an important implication in atmospheric modelling research. However, it has not been explicitly simulated in atmospheric mesoscale models. This study incorporates the RSL model proposed by Harman and Finnigan (2007, 2008) into the Jimenez et al. (2012) SL scheme. A high-resolution simulation performed with the Weather Research and Forecasting model (WRF) illustrates the impacts of the RSL parameterization on the wind, air temperature, and rainfall simulation in the atmospheric boundary layer. As the roughness parameters vary with the atmospheric stability and vegetative phenology in the RSL model, our RSL implementation reproduces the observed surface wind, particularly over tall canopies in the winter season by reducing the root mean square error (RMSE) from 3.1 to 1.8 m s−1. Moreover, the improvement is relevant to air temperature (from 2.74 to 2.67 K of RMSE) and precipitation (from 140 to 135 mm month−1 of RMSE), although its impact is not as substantial as that to wind speed. Our findings suggest that the RSL must be properly considered both for better weather and climate simulation and for the application of wind energy and atmospheric dispersion.