Odor Source Back Trajectory

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mcwilliams@coj.net
Posts: 6
Joined: June 14th, 2021, 10:46 am
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Odor Source Back Trajectory

Post by mcwilliams@coj.net »

. I am a regulator, and we respond to odor complaints. I often use trajectories to get an idea of which facility might be the odor source (this is independent of sending inspectors in the field). I run trajectories using online HYSPLIT with HRRR (archive or forecast) at a height of 10 m AGL (Jacksonville Florida so no terrain issues). The distance of interest is 2 to 10 miles. Many times trajectories have provided useful information. Sometimes not. Any thoughts on our setup?
christopher.loughner
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Joined: August 15th, 2017, 3:59 pm
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Re: Odor Source Back Trajectory

Post by christopher.loughner »

Your setup seems fine. You may want to consider making multiple trajectories with multiple starting heights. HRRR is the highest resolution met product that we have available on READY, so that is a good choice. I suggest comparing HRRR winds with observations to get an idea on model error. Note that HYSPLIT and the met products that are available on READY do not include urban building impacts, so HYSPLIT cannot accurately simulate trajectories through a complex urban environment.

If meteorological observations are available, some users may want to consider using user entered meteorology for short range trajectories, but not in your case since your are located near a coastline with complex sea / land breeze circulations.
mcwilliams@coj.net
Posts: 6
Joined: June 14th, 2021, 10:46 am
Registered HYSPLIT User: Yes

Re: Odor Source Back Trajectory

Post by mcwilliams@coj.net »

We often receive many odor complaints on days when there is an overnight, running into early morning temperature inversion. Would it make sense to set the height to "Automatic mid-boundary layer height?" (option in online version of HYSPLIT)?
alicec
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Joined: February 8th, 2016, 12:56 pm
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Re: Odor Source Back Trajectory

Post by alicec »

Yes this would be a good option to use. It would be good to use that option in conjunction with a few fixed heights to
get an idea of how sensitive your results are to starting height.
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