MET File to use in running Trajectory

Topics about the HYSPLIT trajectory model.
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gmcurcio
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Joined: May 16th, 2015, 12:08 pm
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MET File to use in running Trajectory

Post by gmcurcio » June 22nd, 2019, 2:35 pm

I noticed in using the trajectory tool that it is my thought that the Hybrid Sigma pressure NAM works best at showing trajectories at low initiation altitude. HRRR has the finest resolution but its trajectories were at 100+m when a 2 m trajectory was requested.

I am interested in surface trajectories at 6 feet off the ground, what MET file would be recommended to use. The purpose for such a low trajectory is to track wildfire smoke movement at the surface that would effect humans & drivers on roadways. Anything that is higher is not of concern in this specific situation. At this level how does the trajectory run address or handle the many obstructions to air movement. I assume it assumes vegetation is not there.

barbara.stunder
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Joined: November 9th, 2012, 4:23 pm
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Re: MET File to use in running Trajectory

Post by barbara.stunder » June 24th, 2019, 8:45 am

Please see the Tutorial about trajectories and dispersion. https://ready.arl.noaa.gov/HYSPLIT_Tutorials.php. No single trajectory perfectly represents actual air motion, hence ensembles are preferable to single trajectories.

Even though you are only interested in smoke 6 feet off the ground, what starts at 6 feet likely doesn't stay at 6 feet due to turbulence and vertical motion. Trajectories don't include turbulence, hence the preference for dispersion. The lowest model winds are at 10 m.

Have you run the Prescribed Burn option at https://ready.arl.noaa.gov/HYSPLIT_disp.php? At both forecast and archive dispersion, there is a dropdown list for Release Type that has Prescribed Burn.

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