Mesoscale Flow-Fields and Dispersion in the Coastal Terrain of Eastern Korinthian Gulf in Greece during Summer

Abstract

In order to accurately evaluate environmental impacts from the operation of industrial installations it is necessary to identify some crucial atmospheric parameters such as the development of the Planetary Boundary Layer (PBL) and the 3-D wind field. This is especially true in complex coastal areas where a variety of phenomena including sea-land breezes, convergence zones, drainage flows from surrounding topography, and the development of thermal internal boundary layers make the dispersion processes very complicated (Hanna, 1987; McKendry, 1989). In almost all cases where standard dispersion modelling approaches are applied, some over-simplifications are made for the PBL depth and the wind fields. Such over-simplifications are the spatial homogeneity of the PBL depth and its simple diurnal variation which is usually approximated from indirect methods based on observations and empirical formulation. However, previous studies (Pielke et al., 1983; Glendering et al, 1986; Segal et al., 1988; McKendry, 1989) suggest that large spatial and temporal variations in PBL depth may occur over coastal regions when marine air is advected over land. Of course, significant variations in to the wind field are observed at the same time. These variations are more significant when the marine air incursion occurs over irregular terrain with significant topographic variations. In such cases, even if a dense observational network is available, it is almost impossible to accurately resolve the detailed spatial and temporal variations in both the wind field and PBL depth, parameters considered crucial for detailed air quality investigations. One good approach for such investigations is the use of a mesoscale numerical model capable to accurately describe the PBL depth and wind fields. In addition, with the use of a Lagrangian type dispersion — diffusion model it is possible to investigate the environmental impacts from industrial activities.