How Hysplit treats emission rate and emission duration hour?

Topics about the HYSPLIT dispersion model.
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hlbutterfly
Posts: 7
Joined: September 30th, 2020, 10:56 am
Registered HYSPLIT User: Yes

How Hysplit treats emission rate and emission duration hour?

Post by hlbutterfly »

The same question has been posted under "Hysplit Linux" session but I thought this is more a general question so move here...

I am confused by the way that Hysplit treats the emission rate and the emission duration.

For example, I have two emission scenario. For the first emission scenario, I have a constant emission rate at 100 kg/hr and the emission duration is set to one hour. For the second emission scenario, I still have 100 kg/hr of emissions but the emission duration is only 10 min (the rest 50 min has zero emissions). My Hysplit simulation is one hour and in my SETUP.CFG, I set delt = 1.0. My output temporal resolution is set to 1 min so I have min-by-min concentrations. All other configurations are same except the emission duration (1 hour vs. 10 min). My INITD is set to 3 ("Gaussian-horizontal puff and vertical particle distribution").

Scenario 1 (1 hr emission):
TRACER
100
1


Scenario 2 (10 min emission):
TRACER
100
0.166667


What I expect from these two simulations is that for the first 10 min, the simulated min-by-min concentration should be the same between the two cases simply because for the first 10 min, both scenarios are emitting at 100 kg/hr. However, apparently this is not the case. The simulated concentrations from the two emission scenarios are totally different from each other. So I am very confused of how Hysplit treats the emission rate and the duration.

Thank you very much!
barbara.stunder
Posts: 451
Joined: November 9th, 2012, 4:23 pm
Registered HYSPLIT User: Yes

Re: How Hysplit treats emission rate and emission duration hour?

Post by barbara.stunder »

These scenarios should give the same results.

Look at the MESSAGE files from both the runs.

Verify 1 minute time step for both scenarios -
- DELT = 1.0 in the Namelist configuration list near the top of the file
- in the lines where it has NOTICE: main 1 <time in minutes> <number of particles> <mass in simulation>

Check the total mass at each time step in both the scenarios for the 1st 10 minutes in the same NOTICE lines above.

There is a description of the MESSAGE file at the User's Guide
https://ready.arl.noaa.gov/hysplitusersguide/
Scroll down to the bottom - File Formats - MESSAGE file.

If you can't find anything wrong, post your CONTROL and SETUP files for both runs. You can rename them to have .txt at the end of the file name.
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