A numerical study of mesoscale effects in the coastal climate

When modelling mesoscale effects in the coastal climate we have to account for the significant influence of humidity and for the land-sea contrast which is represented by the roughness lengthz 0 =z 0(x, y) and the heat capacityC 0 =C 0 (x, y). This brings about strong horizontal inhomogenities which affect the meteorological situation significantly. The effects of these inhomogenities on the structure and variation of the boundary layer in the coastal region are studied by use of a three-dimensional numerical model; the formation process of advective fog in connection with different geostrophic winds is also investigated. As main results we present 1) the modifications of wind velocity and wind direction as a function of the roughness distribution and different thermal stratifications and 2) two simulations of advective fog formation assuming different geostrophic wind values in each example.