Impact of NEXRAD derived winds on NARAC dispersion modeling

Matthew Simpson, Lawrence Livermore National Laboratory

Rob Newsome, Pacific Northwest National Laboratory

Impact of NEXRAD derived winds on NARAC dispersion modeling

Observations of winds above the surface are limited due to the coarse temporal, spatial, and vertical resolution of standard rawinsonde soundings. Balloon soundings are typically released twice daily at 00 and 12 UTC from only 72 rawinsonde sites across the continental United States. As a result, the ability to accurately model the dispersion of elevated atmospheric releases is limited due to the lack of upper air data. One approach to improve dispersion modeling of elevated releases is to use winds derived from volume scanning radar data. Gridded upper air winds are calculated from raw NEXRAD radial velocities and a 2-D Variational data assimilation program. The gridded wind fields typically have 6 observation heights over the depth of 100 m to 3000 m above ground level. Dispersion modeling results using NEXRAD wind fields in both diagnostic and prognostic atmospheric models are discussed.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. The Department of Homeland Security sponsored part of the production of this material under the Department of Energy contract DE-AC52-07NA27344 for the management and operation of Lawrence Livermore National Laboratory.