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| Hybrid Single-Particle Lagrangian Integrated Trajectory model | |
|---|---|
| Name | Hybrid Single-Particle Lagrangian Integrated Trajectory model |
| Acronym | HYSPLIT |
| Developer | NOAA Air Resources Laboratory |
| Initial release | 1990s |
| Latest release | ongoing |
| Programming language | Fortran, C, Python (wrappers) |
| Operating system | Cross-platform |
| License | Public domain / NOAA policy |
Hybrid Single-Particle Lagrangian Integrated Trajectory model is a computer model for computing air parcel trajectories, dispersion, and deposition of atmospheric pollutants and tracers. It is used by agencies such as the National Oceanic and Atmospheric Administration, Environmental Protection Agency, European Centre for Medium-Range Weather Forecasts, World Meteorological Organization, and United Nations programs for operational forecasting, emergency response, and research. The model integrates techniques developed for trajectory analysis, Lagrangian particle modeling, and Eulerian frameworks to support studies in air quality, volcanic ash, and radiological assessment.
HYSPLIT combines concepts from trajectory models used by NOAA Air Resources Laboratory, dispersion frameworks related to United States Geological Survey, and atmospheric transport approaches found in NASA projects to produce forward and backward trajectories, concentration fields, and deposition maps. It supports studies tied to events like the Chernobyl disaster, Fukushima Daiichi nuclear disaster, and major volcanic eruptions involving Eyjafjallajökull and Mount Pinatubo. The model is integrated into operational systems at organizations including National Weather Service, European Commission, AirNow partners, and research platforms at institutions such as Scripps Institution of Oceanography and Woods Hole Oceanographic Institution.
Development traces to computational advances in the 1990s at NOAA laboratories influenced by trajectory research at Brookhaven National Laboratory and dispersion techniques from Lawrence Livermore National Laboratory. Early versions addressed needs highlighted by incidents like the Three Mile Island accident and international collaborations under World Meteorological Organization task forces. Subsequent evolution incorporated gridded meteorological datasets from ECMWF, reanalysis products like ERA-Interim and ERA5, and data assimilation concepts from European Space Agency programs, with contributions from researchers affiliated with University of Washington, Colorado State University, and University of Maryland.
HYSPLIT implements a hybrid approach that melds Lagrangian single-particle trajectories with ensemble particle methods and diagnostic Eulerian concentration mapping, reflecting methodologies pioneered in work associated with NOAA Air Resources Laboratory personnel and academic collaborators at Massachusetts Institute of Technology and Pennsylvania State University. The core solver integrates advective transport using winds from gridded datasets provided by agencies like ECMWF and National Centers for Environmental Prediction, while parameterizations for turbulence, wet deposition, and dry deposition draw on formulations used in studies at Imperial College London and University of Cambridge. Numerical schemes are optimized for operational use by groups including Argonne National Laboratory and software practices influenced by standards from IEEE.
HYSPLIT ingests meteorological drivers from sources such as Global Forecast System, ECMWF Reanalysis, North American Mesoscale Forecast System, and satellite-derived products supported by National Aeronautics and Space Administration missions. Emissions and source characterizations are often provided by agencies like Environmental Protection Agency inventories, volcanic ash source terms from observatories including Smithsonian Institution's Global Volcanism Program, and radiological release estimates coordinated with International Atomic Energy Agency protocols. Boundary conditions, land cover, and surface properties interface with datasets curated by United States Geological Survey and climate centers such as NOAA National Centers for Environmental Information.
Operational deployments occur at centers such as National Weather Service forecast offices, Federal Aviation Administration advisories for volcanic ash, emergency response units within FEMA, and international organizations including World Health Organization for transboundary pollutant assessments. Scientific applications span urban air quality studies conducted by California Air Resources Board affiliates, smoke plume tracking for wildfires studied by groups at University of California, Berkeley, and paleoclimate tracer studies linked to projects at Lamont–Doherty Earth Observatory. HYSPLIT supports decision-making during events like volcanic ash advisories that affect International Civil Aviation Organization guidelines and responses to chemical incidents coordinated with Centers for Disease Control and Prevention.
Validation efforts compare HYSPLIT outputs with observations from networks such as AirNow, European Monitoring and Evaluation Programme, and aircraft campaigns led by National Center for Atmospheric Research and NOAA research flights. Studies examining model skill reference intercomparisons with models developed at Max Planck Institute for Meteorology and Institut Pierre-Simon Laplace, and benchmark against other dispersion systems used by Atomic Energy Commission successors. Limitations stem from meteorological input resolution, uncertainties in emission source terms from agencies like United Nations Environment Programme, and simplifications in microphysical deposition processes discussed in literature from Royal Society. Ensemble approaches and sensitivity analyses involving partner institutions such as University of Colorado Boulder help quantify uncertainty.
HYSPLIT is distributed by NOAA Air Resources Laboratory with executables and source for platforms used at research centers including Argonne National Laboratory and universities such as Iowa State University. Interfaces and wrappers in languages used at Lawrence Berkeley National Laboratory and Carnegie Mellon University facilitate integration into workflows, and web-based access is provided through portals supported by NOAA National Weather Service and cooperating centers including Australian Bureau of Meteorology. Training and documentation are produced in collaboration with agencies like Environmental Protection Agency and academic partners at Colorado State University, while community extensions and examples circulate through workshops hosted by American Meteorological Society.
Category:Atmospheric dispersion models