Hello!
I am trying to interpret the HYSPLIT dispersion output for a location where back trajectories frequently hit the ground. I followed previous forum discussions on trajectory versus dispersion settings. I also explored Tutorial 13.3 and the batch script. What is the unit of the dispersion output if I assign unit emission at the receptor? Could you elaborate on when to assign 0 or 1 to Q?
Thank you!
Unit for dispersion output
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dahalsishir
- Posts: 1
- Joined: August 25th, 2026, 3:58 pm
- Registered HYSPLIT User: No
Re: Unit for dispersion output
If you are running a regular backward HYSPLIT dispersion run (hycs_std or hycm_std) with IDSP=1 (which is the default)
and assigning a unit emission rate as described here -
https://www.ready.noaa.gov/hysplitusersguide/S312.htm
Then air concentrations will be in unit mass per meter cubed.
If you define a deposition layer then the unit in the deposition layer is unit mass per meter squared.
To define a deposition layer, the first level in the Height of levels field is 0.
See
https://www.ready.noaa.gov/hysplitusersguide/S313.htm
and assigning a unit emission rate as described here -
https://www.ready.noaa.gov/hysplitusersguide/S312.htm
Then air concentrations will be in unit mass per meter cubed.
If you define a deposition layer then the unit in the deposition layer is unit mass per meter squared.
To define a deposition layer, the first level in the Height of levels field is 0.
See
https://www.ready.noaa.gov/hysplitusersguide/S313.htm