HYSPLIT Model Update to be Released to the Public

A major update to the HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model will be released to the public, as a downloadable version, through the Air Resources Laboratory’s web site on February 24th. Many of the changes made by ARL since the last update (February 2008) are technical improvements, including the availability of higher spatial resolution meteorological data archives and forecasts. There also have been substantial modifications to the user interface to provide a more consistent color scheme through all the menus. The model is available for download for Windows or Apple systems.

Background: ARL’s HYSPLIT model can be used to compute either single air parcel trajectories or more complex dispersion and deposition simulations. The model calculation method is a hybrid between the Lagrangian approach, which uses a moving frame of reference as the air parcels move from their initial location, and the Eulerian approach, which uses a fixed three-dimensional grid as a frame of reference. In the model, advection and diffusion calculations are made in a Lagrangian framework while pollutant concentrations are calculated on a fixed grid. HYSPLIT can be run interactively on ARL’s Real-time Environmental Applications and Display System web site, or it can be installed on a PC and run using a graphical user interface. Operationally, the model is used by NOAA’s National Weather Service through the National Centers for Environmental Prediction and at local Weather Forecast Offices.

Significance: The accidental or intentional release of hazardous air pollutants can have significant health, safety, homeland and national security, economic, and ecological implications. The HYSPLIT model is a tool that helps explain how, where, and when chemicals and materials are atmospherically transported, dispersed, and deposited. Having this understanding is essential for responding appropriately and preventing disaster. For instance, accurate predictions of the path of a chemical release help emergency managers evacuate the right people. Predictions of volcanic ash plume locations allow aircraft to avoid dangerous areas. Understanding the sources of hazardous air pollutants allows air quality managers to develop targeted policies and plans to mitigate the problem.

For More Information, contact:

Dr. Roland Draxler