Sensitivity tests in the dynamical and thermal part of the MRF-urban PBL scheme in the MM5 model

Abstract

In the present study, sensitivity tests were carried out in the 'dynamical' and 'thermal' part of a meteorological model in urban environment. The numerical simulations were performed by the PSU/NCAR Mesoscale Model (MM5), by applying the non-local Medium-Range Forecast (MRF) Planetary Boundary Layer (PBL) parameterisation scheme, plus the MRF-urban scheme, whereby urban features are considered. An unrealistic run was also performed by the MRF scheme, where the city of Athens was replaced by dry cropland and pasture surface, as in the surrounding area. The model results were compared with sonic anemometer measurements of turbulence and routine meteorological data. Modifications in both the 'dynamical' and 'thermal' parts seem to play an important role and improve the model's results. In addition, a delay in the sea breeze front was found, and a reasonable frictional retard concerning its penetration, as well as an inland displacement of the heat island, as the air moved over the city of Athens. © Springer-Verlag Berlin Heidelberg 2009.