Objective
The purpose of this modeling effort was to provide the Defense Threat Reduction Agency (DTRA) with wind and other boundary-layer data to be used for transport and dispersion calculations in the event hazardous material was released into the atmosphere during the Torino Winter Olympics. The location of the games provided an ideal testbed to demonstrate new capabilities of the RAL modeling team in an area of highly complex topography.
Description
During the Torino Winter Olympic games, NCAR operated a mesoscale data-assimilation and forecast system that provided analyses and forecasts of winds on a variety of scales, from Western Europe to the scale of individual Alpine valleys. The initial setup of the modeling system was challenging because of the presence of large topographic gradients and the large horizontal extent (more than 125 miles wide at their broadest point) of the Alps.
Two data-assimilation and forecast modeling systems operated in parallel during the games: an MM5-based system, similar to the system developed by RAL for Army test-range support, and a newer WRF-based system. The grid increment of the inner-most grid was 1.1 km in the WRF-based system, and was capable of representing the thermal and dynamic effects of individual Alpine valleys. In addition to the local near-surface and satellite data assimilated by the model, a new scheme was developed to mask initial snow depth using high-resolution satellite-derived NOAA/NESDIS snow and ice coverage.
