MEMO, which was developed by the Laboratory of Heat Transfer and Environmental Engineering of AUTh in cooperation with the University of Karlsruhe, is a prognostic mesoscale model, which allows describing the air motion and the dispersion of inert pollutants over complex terrain. The code allows one way nesting. Within MEMO, the conservation equations for mass, momentum, and scalar quantities as potential temperature, turbulent kinetic energy and specific humidity are solved. The governing equations are solved in terrain-influenced co-ordinates. Non-equidistant grid spacing is allowed in all directions. The numerical solution is based on second-order discretisation applied on a staggered grid. Conservative properties are fully preserved within the discrete model equations. The discrete pressure equations are solved with a fast elliptic solver in conjunction with a generalized conjugate gradient method. Advective terms are treated with the TVD scheme. Turbulent diffusion can be described with either a zero-, one- or two-equation turbulence model. At roughness height similarity theory is applied. The radiative heating / cooling rate in the atmosphere is calculated with an implicit multilayer method for shortwave radiation. The surface layer over land is computed from the surface heat budget equation. The soil temperature and moisture content are calculated by solving an one dimensional heat conduction equation and moisture flux equation respectively. At lateral boundaries and for scalar quantities Neumann or Dirichlet conditions are applied. At lateral boundaries generalized radiation conditions are implemented.
The application of MEMO requires the availability of orography data and meteorological parameters, such as temperature (potential or not), wind velocity. The dimensions of the study area, the area’s longitude and latitude and various thermo-physical data, such as like average monthly ground and sea temperatures, reflection, volumetric heat capacity, exhaust parameter and heat diffusion of different ground types (land-use).