Lateral Diffusion within Plume

Topics about the HYSPLIT dispersion model.
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kjmohr
Posts: 21
Joined: June 22nd, 2020, 3:05 pm
Registered HYSPLIT User: Yes

Lateral Diffusion within Plume

Post by kjmohr » July 13th, 2020, 6:03 pm

Hello,

I have been running a coupled HySPLIT model with a volcanic plume model and our volcanic depositions are extremely narrow, to where it does not seem there is really any lateral diffusion within the plume. I was wondering if there is a way to change the lateral diffusion within the plume? I see there is a horizontal turbulence parameter, would that be the most similar thing to changing the lateral diffusion (as in, make the deposit more broad and less narrow)?

Thank you,

Kyle

alicec
Posts: 234
Joined: February 8th, 2016, 12:56 pm
Registered HYSPLIT User: Yes

Re: Lateral Diffusion within Plume

Post by alicec » July 15th, 2020, 4:41 pm

Often the turbulent mixing in volcanic plume simulations is quite low as the mixing decreases with height.
To increase mixing you can try several things.

https://ready.arl.noaa.gov/hysplitusersguide/S625.htm

Use kzmix and tvmix to increase the mixing coefficients.

Try using kdef=1 to compute horizontal turbulence from velocity deformation.

If you are using a vertical line source for your eruption, you may also want to try using a wider source term.

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