Research Highlight:
ARL Delivers Improved HySPLIT capabilities to NWS

The Air Resources Laboratory (ARL) delivered model enhancements to the National Weather Service’s National Centers for Environmental Prediction (NCEP) for their operational Hybrid Single-Particle Lagrangian Integrated Trajectory (HySPLIT) transport and dispersion model. These enhancements allow for long-range dispersion beyond 4 days and for back-tracking capabilities and for generating additional output graphical formats, such as that used by Google Earth. In addition, these enhancements include the capability to drive HySPLIT with winds from additional analysis and forecast modeling systems: Global Data Assimilation System; Global Forecast System long range 2.5 degree files; and Rapid Update Cycle model.

The HySPLIT transport and dispersion model, developed by ARL, is run operationally at NCEP as needed, to respond to or participate in exercises for explosive volcanic eruptions and radiological or other hazardous atmospheric releases, and on a daily basis to provide fire smoke forecasts ( Dispersion forecasts support weather forecasters at NWS Weather Forecast Offices, who in turn support local emergency managers. Volcanic ash and radiological forecasts are provided under the auspices of the International Civil Aviation Organization and World Meteorological Organization, respectively, through NCEP’s role as the Volcanic Ash Advisory Center and Regional Specialized Meteorological Center for Environmental Emergency Response.

These new capabilities greatly enhance and support the NWS’s atmospheric dispersion forecasting capability. For the radiological application, long-range forecasts now will be used to help answer questions such as “When and where will radioactivity from an overseas incident reach the U.S.?” Back-tracking capabilities will allow estimations of source areas when high radioactivity levels are measured but the source is unknown. For small-scale incidents, Google Earth output graphical formats are considered preferable by some customers.