Documents of backtrajectory/backdispersion analysis

Topics about the HYSPLIT trajectory model.
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hooman18968
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Joined: April 15th, 2022, 4:47 am
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Documents of backtrajectory/backdispersion analysis

Post by hooman18968 »

Hi everyone,

I need the documents explaining the detailed equations of backward analysis (both advection only and dispersion) in Hysplit. I took a look at user_guide and arl_224, but I couldn't find how the backward analysis is done. For example, we know the forward trajectory analysis is:

P'(t+Δt) = P(t) + V(P,t) Δt
P(t+Δt) = P(t) + 0.5 [ V(P,t) + V(P',t+Δt) ] Δt,

What about the backward analysis?

The same question I have about the backdispersion.

Cheers,
Hooman
alicec
Posts: 418
Joined: February 8th, 2016, 12:56 pm
Registered HYSPLIT User: Yes

Re: Documents of backtrajectory/backdispersion analysis

Post by alicec »

The trajectory calculations are the same, just time is reversed.

P'(t-Δt) = P(t) + V(P,t)(-Δt)
P(t-Δt) = P(t) + 0.5 [ V(P,t) + V(P',t-Δt) ] (-Δt),

The turbulent dispersion calculation just stays the same. I would recommend this paper to
understand this better.

Utility of atmospheric transport runs done backwards in time for source term estimation
By:Eslinger, PW (Eslinger, Paul W.)[ 1 ] ; Schrom, BT (Schrom, Brian T.)[ 1 ]
JOURNAL OF ENVIRONMENTAL RADIOACTIVITY
Volume: 203 Pages: 98-106
DOI: 10.1016/j.jenvrad.2019.03.006
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