LOCAL SIMULATIONS OF LAND-SEA BREEZE CYCLES IN ATHENS BASED ON LARGE-SCALE OPERATIONAL ANALYSES

Two different episodes of land-sea breeze evolution in the Athens area are numerically investigated using a non-hydrostatic mesoscale model, with E-epsilon turbulence closure, in the framework of the APSIS proj ect. The initialization and the time evolving boundary conditions are derived from the ECMWF operational analyses. The simulated surface win ds have been compared with available surface measurements. On these tw o situations, the use of operational analyses imposed on the boundary of a local model provides more realistic simulations than those based only on local soundings. The results obtained are closer to more sophi sticated nested simulations except in a relaxation zone near the bound aries. The urbulence predicted by the E-epsilon turbulence model is ve ry weak in early morning and increases to values representative of mod erately convective conditions during the day in correspondence with th e observed poor dispersion of pollutants. (C) 1996 Elsevier Science Lt d