Description
NOAA’s HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory) website provides access to a powerful atmospheric transport and dispersion model used to simulate how airborne pollutants, smoke, dust, volcanic ash, and other particles move and spread in the atmosphere. The site offers model documentation, tutorial materials, downloadable desktop software, and online web-based tools that let users calculate air parcel trajectories, dispersion, and deposition patterns based on meteorological data. It is widely used for air quality studies, emergency response, and research on long-range transport of contaminants.
Questions this resource can help answer
Where will a pollutant, smoke plume, or gas release travel over the next few hours or days?
Which downwind communities or regions are most likely to be affected by an emission event, and when might they be impacted?
How do different release heights, times, or meteorological conditions change the predicted transport and dispersion pattern?
Where is material from a source likely to be deposited on the ground (wet or dry deposition “footprints”)?
What are typical transport pathways for dust, smoke, or pollutants from a given region over a season or year?
How do I use this resource?
To use HYSPLIT via NOAA’s web tools, first create an account (if required) and choose whether you want a trajectory (where air came from or will go) or dispersion (how a pollutant/cloud spreads) calculation. Select the meteorological dataset, then specify your start location (latitude/longitude or map click), start time, height above ground, and run duration. For dispersion runs, also set source characteristics (release duration, emission rate, and pollutant/particle type) and output options. Submit the job, then view the resulting maps and tables showing trajectories or concentration/deposition fields; adjust inputs (e.g., height, time, met data) and rerun as needed. For more advanced or batch work, download the desktop HYSPLIT model and follow the user guides and tutorials provided on the site.
Pro tips
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Resource information
Technical specifications
HYSPLIT is an atmospheric transport and dispersion model that combines Lagrangian and Eulerian approaches. It uses gridded meteorological data (winds, temperature, turbulence, precipitation) to move thousands of virtual particles or air parcels forward or backward in time, calculating trajectories (pathways in space and height) and how a released pollutant cloud spreads, dilutes, and deposits. Advection is computed from the 3?D wind fields, while turbulent diffusion is represented with stochastic (random) motions based on atmospheric stability and turbulence parameters; for dispersion runs, particle concentrations are then mapped onto a fixed grid to create concentration and deposition fields. This hybrid method allows HYSPLIT to simulate everything from simple air parcel paths to complex plumes from industrial releases, wildfires, or volcanic eruptions.
