Optimizing the use of existing federal data to improve the atmospheric dispersion forecasts for an effective emergency response

UrbanNet (formerly DCNet) database provides a unique opportunity data to improve dispersion model predictions for urban applications. The meteorological observations made across the greater National Capital Region (NCR) can be used to support the evaluation and improvement of numerical weather prediction models as well as to provide meteorological observations to drive dispersion models for emergency applications. The UrbanNet network has been operating by NOAA Air Resources Laboratory since 2003 to collect meteorological measurements in Washington, D.C. The locations of UrbanNet measurements are spread across the District of Columbia and its surrounding suburbs. Of these stations, the installation atop the U.S. Department of Commerce Herbert C. Hoover Building (HCHB) at 1401 Constitution Avenue, Northwest, Washington, DC (38.894⁰N, 77.033⁰W) has been the subject of most recent attention.

In this study, UrbanNet data from the HCHB station have been used to enhance the predictions of the Weather Research and Forecasting (WRF) meteorological model through observational nudging to improve temperature and wind predictions. NOAA’s dispersion model, HYSPLIT, was utilized to understand the impact of using the observational nudged WRF fields in dispersion modeling.

In addition to the meteorological measurements obtained at the top of HCHB, the meteorological observations collected from the National Weather Service (NWS) monitoring stations located at the major regional airports in Washington, DC were also assimilated into WRF modeling along with the HCHB data. The NWS station at Ronald Reagan National Airport (DCA) is located approximately 5 kilometers south of the HCHB complex. Another NWS station at Dulles International Airport (IAD) is located roughly 35 km northwest of the HCHB complex. The comparison of HYSPLIT simulations with and without the enhancement of the WRF model using UrbanNet and NWS data shows substantial differences. These findings demonstrate that local observations provide important opportunities to improve the predictions of hazardous material dispersion in a complex environment such as an urban area and to determine impacts from the airborne release of chemicals.