Joint Urban 2003 - Oklahoma City

Objective

In the summer of 2003, a field program was conducted in Oklahoma City to study atmospheric transport and diffusion in an urban environment. NCAR provided mesoscale modeling support for field-program operations.

Description

Joint Urban 2003 was the largest urban field program ever undertaken and the NCAR modeling activities provided forecasts for planning intensive observation periods. These forecasts were used to develop improvements in the model’s ability to realistically render urban boundary-layer properties. Five MM5-model grids were used in the nested modeling system, with the highest-resolution grid having a grid increment of 500 m. In addition to the MM5 model, the Variational Doppler Radar Assimilation System (VDRAS) was used to assimilate local NEXRAD radar data to produce analyses and 1-hour forecasts of boundary layer winds and other properties. Both MM5 and VDRAS winds were used as input to a transport and dispersion model to permit field-program managers to anticipate the transport of releases of chemical tracers used in the study.