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Daily Limits

Users are limited to 500 trajectories per day in order to share the resources available with all HYSPLIT users.

Publishing HYSPLIT results

Publications using HYSPLIT results, maps or other READY products provided by NOAA ARL are requested to include an acknowledgement of, and citation to, the NOAA Air Resources Laboratory. Appropriate versions of the following are recommended:


Stein, A.F., Draxler, R.R, Rolph, G.D., Stunder, B.J.B., Cohen, M.D., and Ngan, F., (2015). NOAA's HYSPLIT atmospheric transport and dispersion modeling system, Bull. Amer. Meteor. Soc., 96, 2059-2077,

Rolph, G., Stein, A., and Stunder, B., (2017). Real-time Environmental Applications and Display sYstem: READY. Environmental Modelling & Software, 95, 210-228, (


The authors gratefully acknowledge the NOAA Air Resources Laboratory (ARL) for the provision of the HYSPLIT transport and dispersion model and/or READY website ( used in this publication.

Redistribution Permission

Permission to publish or redistribute HYSPLIT model results using forecast meteorological data from NOAA ARL can be obtained by providing relevant information (reason, to whom, from whom) via email to For further information, see the HYSPLIT Use Agreement.

Modified: December 4, 2019
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