Wind Field and Pollutant Dispersion Analysis in Greater Athens Area Using the Euridice Code System

Abstract

The EURIDICE Code System, a joint effort by the CEA-France and DEMOKRITOS-Greece, performs wind field calculations and atmospheric dispersion analysis in meso and/or micro-scale level, over terrains of any complexity. Within the EURIDICE framework, the wind field is calculated by the ADREA code, which is a time dependent, 3-D compressible, non-hydrostatic code, treating the ground as a porous medium. The concentration of airborne and deposited pollutants is calculated by the MC31 code which solves the diffusion-advection equation by a MONTE-CARLO method. The modelling approach used in both codes permits the capability of utilizing detailed topography description, approaching reality: the calculational cell can include many ground surface elements of arbitrary size with their own identities (orientation, area, albedo, sunshade, soil type, roughness, deposition velocity, moisture etc). This is obtained by the DELTA code which provides the topography description using adjacent triangular surfaces in number and size depending only on the accuracy required. DELTA also calculates rain water runoff trajectories and accumulation points on the ground. For illustration purposes, the EURIDICE Code system has been used to simulate the wind field in the Greater Athens Area (GAA) and calculate the dispersion of a radioactive pollutant released from a point source located in the suburban area of the city.