THE DISPERSION OF TRACER PLUMES IN MOUNTAINOUS REGIONS IN CENTRAL ARIZONA - COMPARISONS BETWEEN OBSERVATIONS AND MODELING RESULTS

A three-dimensional, time-dependent, nested-grid model is used to calc ulate the targeting of tracer or seeding material over complex terrain in northern Arizona. Good agreement with measurements of SF6 tracer i s reported in three case studies. Released in upwind valleys, the trac er movement and dispersion are strongly influenced by both valley flow and gravity waves excited by the mountains, as well as by changes in the synoptic flow, which can change substantially even during a single storm. The interaction between the airflow and the topography seem to be the dominant factor determining the dispersion and transport of tr acer material.