NOAA Air Resources Laboratory

HYbrid Single-Particle
Lagrangian Integrated Trajectory Model

Version 4.8 Updated: February 2008

HYSPLIT Icon


HYSPLIT Description

The HYSPLIT (HYbrid Single-Particle Lagrangian Integrated Trajectory) model is the newest version of a complete system for computing simple air parcel trajectories to complex dispersion and deposition simulations. As a result of a joint effort between NOAA and Australia's Bureau of Meteorology, the model has recently been upgraded. New features include improved advection algorithms, updated stability and dispersion equations, a new graphical user interface, and the option to include modules for chemical transformations. Without the additional dispersion modules, Hysplit computes the advection of a single pollutant particle, or simply its trajectory.

The dispersion of a pollutant is calculated by assuming either puff or particle dispersion. In the puff model, puffs expand until they exceed the size of the meteorological grid cell (either horizontally or vertically) and then split into several new puffs, each with it's share of the pollutant mass. In the particle model, a fixed number of initial particles are advected about the model domain by the mean wind field and a turbulent component. The model's default configuration assumes a puff distribution in the horizontal and particle dispersion in the vertical direction. In this way, the greater accuracy of the vertical dispersion parameterization of the particle model is combined with the advantage of having an ever expanding number of particles represent the pollutant distribution.

The model can be run interactively on the Web through the READY system on our site or the code executable and meteorological data can be downloaded to a Windows PC. The Web version has been configured with some limitations to avoid computational saturation of our web server. The registered PC version is complete with no computational restrictions, except that user's must obtain their own meteorological data files. The unregistered version is identical to the registered version except that it will not work with forecast meteorology data files.


Model Features

    Trajectories

    • Single or multiple (space or time) simultaneous trajectories
    • Optional grid of initial starting locations
    • Computations forward or backward in time
    • Default vertical motion using omega field
    • Other motion options: isentropic, isosigma, isobaric, isopycnic
    • Trajectory ensemble option using meteorological variations
    • Output of meteorological variables along a trajectory

    Air Concentrations

    • 3D particle dispersion or splitting puffs (top-hat or Gaussian)
    • Instantaneous or continuous emissions, point or area sources
    • Multiple resolution concentration output grids
    • Fixed concentration grid or dynamic sampling
    • Wet and dry deposition, radioactive decay, and resuspension
    • Emission of multiple simultaneous pollutant species
    • Automated source-receptor matrix computation
    • Ensemble dispersion with concentration probability output
    • Integrated dust-storm emission algrorithm
    • Define rate constants to convert one species to another

    Meteorology

    • Model can run with multiple nested input data grids
    • Links to ARL and NCEP meteorological data server
    • GUI integrated GRIB decoding for NAM, GFS, and ECMWF data
    • Access to forecasts and archives including NCAR/NCEP reanalysis
    • Additional software to convert MM5, RAMS, COAMPS, and other data
    • Utility programs to display and manipulate meteorological data

    Common Features

    • Tcl/Tk GUI with integrated html compatible help
    • Viewer to display TOMS or AVHRR with particle positions
    • Model restart from particle position files for plume initialization
    • Model graphics displayed as Postscript files
    • Converters to many other formats: GIF, GrADS, ArcView, Vis5D


    Highlights of Recent Updates

    February 08 Revision (4.8)

    • new concentration grid plot color fill program and added to GUI
    • revised conprob files (and GUI) to be consistent with box plots
    • new GUI for box plots for ensemble simulation results
    • UNIX testing script for version control
    • emitimes permits multiple species on one particle when maxdim>1
    • improved puff split-merge algorithm and added new namelist options
    • removed FTP of NCEP GRIB-1 files from GUI menus
    • added additional download options for HYSPLIT compatible data files

    November 07 Revision (4.8)

    • Plotting routines were modified in terms of centering, colors, and clipping
    • Units were changed in the source-attribution code for consistency
    • The internal vertical grid structure was corrected for high resolution input data
    • Emissions were corrected to handle releases shorter than the model's time step
    • The termination message shows if points fall outside the domain in terms of space or time
    • Additional puff split-merge factors were moved from the constants to the namelist input
    • A multi-trajectory geo-location option based upon measurment data was added to the GUI menu
    • Cluster number labels were added to the trajectory plotting program
    • A new GUI tab can be used to install model updates when they become available

    August 2007 Revision (4.8)

    • Mixed layer depth computed from minimum temperature
    • Default short-range turbulence from profiles rather than fluxes
    • Terrain correction for starting heights above mean sea level
    • Automated source attribution configuration from measured data
    • Integrated solution of the source-receptor matrix
    • Modified meteorological data input algorithm for sfc obs

    March 2007 Revision (4.8)

    • Options to set the day/night anisotropy when using TKE fields
    • Automatic selection of the most recent forecast data file
    • New options to compute maximum and maximum average concentrations
    • Updated namelist configuration menus with more information
    • New map projections and latitude-longitude labeling options
    • More flexible data FTP with server selection and progress widget

    Meteorological Data

    The meteorological input fields used by Hysplit are required to be in "ARL packed" format. All gridded meteorological data available on our site are already in this form and may be FTP'd to your PC without conversion. Remember to use the binary or iget options for any data transfers.

    All data meteorological available on our site on-line may be used through any Web based READY program, or with some restrictions, downloaded to your PC for computations. Data that is no longer on-line may be available from NCDC or other sources, however it cannot be placed back on-line and all computations with those data must be done locally on your own PC.



    Hysplit On-Line Publications

    Due to copyright restrictions, some articles are not available directly on-line, but must be requested by Email. You will be prompted, the article file name will appear in the subject line, no additional message is necessary.

    Short Range: 5 to 50 km Applications - Draxler, R.R., 2006, The Use of Global and Mesoscale Meteorological Model Data to Predict the Transport and Dispersion of Tracer Plumes over Washington, D.C., Weather and Forecasting, Vol. 21, No. 3, pages 383-394.

    Modeling PM10 from Dust Storms - Escudero, M., A. Stein, R. R. Draxler, X. Querol, A. Alastuey, S. Castillo, and A. Avila (2006), Determination of the contribution of northern Africa dust source areas to PM10 concentrations over the central Iberian Peninsula using the Hybrid Single-Particle Lagrangian Integrated Trajectory model (HYSPLIT) model, J. Geophys. Res., 111, D06210, doi:10.1029/2005JD006395.

    HYSPLIT meteorological ensemble method - Draxler, R.R. 2003, Evaluation of an ensemble dispersion calculation, Journal of Applied Meteorology, Vol. 42, February, 308-317.

    HYSPLIT turbulence ensemble method - Stein, A.F., V. Isakov, J. Godowitch, R.R. Draxler (2007),A hybrid modeling approach to resolve pollutant concentrations in an urban area, Atmospheric Environment 41:9410-9426.

    Hysplit User's Guide - An essential document if you will be using the Windows PC version of the model. The document provides complete information about file formats, command line prompts, and descriptions of each input line for the Hysplit model's control file that is used to set up the simulation (NOAA Tech Memo ERL ARL-230, June 1999, 35p - Last Revised March 2002 - also included in the distribution download file).

    Hysplit Ozone Calculations - Draxler, R.R. 2000, Meteorological Factors of Ozone Predictability at Houston, Texas, J. Air and Waste Management Assoc., 50: 259-271.

    Verification and Examples - Draxler, R.R. and G.D. Hess, 1998, An Overview of the Hysplit_4 Modeling System for Trajectories, Dispersion, and Deposition, Aust. Met. Mag., 47, 295-308.

    Technical Information - Draxler, R.R. and G.D. Hess, 1997, Description of the Hysplit_4 modeling system, NOAA Tech Memo ERL ARL-224, Dec, 24p.

    Emergency Response Applications - Draxler, R.R., Jean, M., Hicks, B., and Randerson, D. 1997, Emergency Preparedness, Regional Specialized Meteorological Centers at Washington and Montreal, Radiation Protection Dosimetry, Vol 73, pp. 27-30.

    Volcanic Eruptions - Stunder, B.J.B., J.L. Heffter, R.R. Draxler (2007), Airborne Volcanic Ash Forecast Area Reliability, Weather and Forecasting, 22:1132-1139, DOI: 10.1175/WAF1042.1

    Trajectory Verification - Draxler, R.R. 1996, Trajectory Optimization for Balloon Flight Planning, Weather and Forecasting, Vol 11, March, pp. 111-114.

    Kinematic and Isentropic Trajectories - Draxler, R.R. 1996, Boundary layer isentropic and kinematic trajectories duing the August 1993 North Atlantic Regional Experiment Intensive, J. Geophys. Res., Vol 101, No. D22, pp. 29255-29268.