The influence of model resolution on an expression of the atmospheric boundary layer in a single-column model

An expression of the atmospheric boundary layer, which is important for meteorological forecast, depends on model resolution. We investigated the influence of model resolution (time steps and vertical resolution) on vertical diffusion using the experiment system of the second intercomparison project of GABLS. Japan Meteorological Agency plans to enhance vertical resolution of Global Spectrum Model from 40 to 60 layers with increase in horizontal resolution from 55km to 20km in 2007. We made vertical resolution mainly detailed in a lower atmosphere detailed to improve the expression of the atmospheric boundary layer. We investigated the influence of this improvement on vertical diffusion focusing on the diurnal cycle of the structure of the atmospheric boundary layer, surface air temperature and surface wind. The surface weather is influenced by not only the atmospheric boundary layer but also land surface properties. Therefore, we also investigated the influence of land surface on vertical diffusion. We found that vertical diffusion in the atmospheric boundary layer was influenced by model resolution and land surface properties.