TRANSALP 1989 EXPERIMENTAL CAMPAIGN - II - SIMULATION OF A TRACER EXPERIMENT WITH LAGRANGIAN PARTICLE MODELS

The capability of two 3D Lagrangian particle models (ARCO and SPRAY) i n simulating the airborne dispersion in highly complex terrain is test ed. The simulations are compared to,the tracer experiment TRANSALP-I p erformed on the 19th of October 1989 in the Alpine region (Canton of T icino, Switzerland). TRANSALP exercises were part of the EUROTRAC-TRAC T Subproject. Tracer was released during one hour (11.00-12.00) near t he ground at Iragna, a few kilometres upwind from the bifurcation of t wo valleys (Leventina and Blenio Valleys); about 40 samplers, located in the two valleys in the range of 40 km, measured 1/2 h average mean concentrations near the ground for five hours. The results of the simu lations are presented and discussed. A statistical model evaluation ai med at quantifying the performance of the two models was carried out. The simulations reproduced with a reasonable degree of accuracy the ge neral behaviour of the observed phenomena: the split of the plume betw een the two valleys, the space and time distribution of the concentrat ion, the concentration maxima locations. (C) 1998 Published by Elsevie r Science Ltd. All rights reserved.