Mixing Height for Back Trajectory

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Hossan
Posts: 8
Joined: May 20th, 2019, 4:53 pm
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Mixing Height for Back Trajectory

Post by Hossan » May 30th, 2019, 1:19 pm

Hi,
I have run 3 trajectories with start height of 500m, 1000m, and 1500m for the same time and latitude and longitude and same meteorological file. I have added mixing depth as meteorology output with default pressure.

In endpoint files: I see mixing height of 1000m trajectory less than the 500m trajectory run; Why mixing height is different for each trajectory for the same location and time?
I am not a meteorology expert. So, Couldn't figure out how meteorology works and how HYSPLIT works in that context.

Any helps would be greatly appreciated.
end point data.PNG

christopher.loughner
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Joined: August 15th, 2017, 3:59 pm
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Re: Mixing Height for Back Trajectory

Post by christopher.loughner » May 31st, 2019, 4:44 pm

Hi,

Thanks for helping me identify a bug. It appears HYSPLIT is printing out the location at the starting time, but the mixing depth after one timestep. It is also calculating the first timestep twice. I am currently testing a bug fix. I will reply back after I post a fix to the Linux version to the repository. Note that this bug has a very small impact on the results.

Chris

Hossan
Posts: 8
Joined: May 20th, 2019, 4:53 pm
Registered HYSPLIT User: Yes

Re: Mixing Height for Back Trajectory

Post by Hossan » June 3rd, 2019, 10:59 am

Hi Chris,
Thanks for your reply.

Waiting for your findings.

Thank you so much.

Iqbal

christopher.loughner
Posts: 17
Joined: August 15th, 2017, 3:59 pm
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Re: Mixing Height for Back Trajectory

Post by christopher.loughner » June 6th, 2019, 3:39 pm

An update has been committed to the repository for the Linux version (Version 1011). If you don't have access to the source code, for now you can obtain the mixing height at the initial time and location of your trajectory using the profile program. If you are using the gui, click on Meteorology -> Display Data -> Text Profile.

Chris

Hossan
Posts: 8
Joined: May 20th, 2019, 4:53 pm
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Re: Mixing Height for Back Trajectory

Post by Hossan » June 10th, 2019, 8:58 am

Hi,
I don't have access to linux version. Do you think Windows Version also has bug?. I have used windows version to get attached end point file.

Could you please help me on that?

Thanks

christopher.loughner
Posts: 17
Joined: August 15th, 2017, 3:59 pm
Registered HYSPLIT User: No

Re: Mixing Height for Back Trajectory

Post by christopher.loughner » June 10th, 2019, 10:45 am

Hi,

The extra timestep is only a 1 minute timestep. In my tests, I only see differences between the old and updated versions at the initialization time. So, if you want correct the pressure and any diagnostic output (mixing depth for your case) at the initialization time, then I suggest running the profile program to extract these variables. See my previous post about how to do this.

Chris

Hossan
Posts: 8
Joined: May 20th, 2019, 4:53 pm
Registered HYSPLIT User: Yes

Re: Mixing Height for Back Trajectory

Post by Hossan » June 10th, 2019, 12:03 pm

Thank you so much for the help.
So, I am trying to get mixing height on 17 06 02 17 (YYMMDDHH) from NAM-12k met data (ftp://arlftp.arlhq.noaa.gov/pub/archives/nam12).
Since, This dataset has 3 hours interval data (from my knowledge, i might be wrong), I couldn't able to get mixing depth for that particular hour (attached screenshots). I have tried different combination of time offset and time increment in GUI.

Could you please help me on this?

Thanks in advance
Attachments
Profile file Met data.PNG
Profile file Met data 2.PNG

christopher.loughner
Posts: 17
Joined: August 15th, 2017, 3:59 pm
Registered HYSPLIT User: No

Re: Mixing Height for Back Trajectory

Post by christopher.loughner » June 11th, 2019, 11:33 am

Hi,

You can use the vmixing program to extract mixing height for any time. In a command shell, move to the directory with your CONTROL and SETUP.CFG files and then execute vmixing ({directory of hysplit4\exec}\vmixing.exe -s2 -t2). The variable Zi in the output STABILITY.txt is the mixing height depth. The below example shows a mixing depth of 730.5 m at 42.77 -86.15 on June 10, 2017 at 17 UTC.

PS C:\test_vmixing> ..\hysplit4\exec\vmixing.exe -s2 -t2
PS C:\test_vmixing> ls


Directory: C:\test_vmixing


LastWriteTime Length Name
6/10/2019 1:16 PM 445780032 20170607_nam12
6/10/2019 1:16 PM 445780032 20170608_nam12
6/10/2019 1:16 PM 445780032 20170609_nam12
6/10/2019 1:16 PM 445780032 20170610_nam12
3/13/2019 2:10 PM 271 ASCDATA.CFG
6/10/2019 1:41 PM 333 CONTROL
6/10/2019 1:42 PM 1180 MESSAGE
6/10/2019 1:39 PM 360 SETUP.CFG
6/10/2019 1:42 PM 334 STABILITY..txt
6/10/2019 1:42 PM 0 WARNING


PS C:\test_vmixing> more .\STABILITY..txt
42.77 -86.15 NAM
JDAY YR MO DA HR MN PSQ Zi 10xKz U* Zo Zterr Kh
(m) (m2/s) (m/s) (m) (m) (m2/s)
161.708 17 6 10 17 0 G 0.7305E+03 NaN NaN 0.2812E+00 0.1848E+03 NaN

PS C:\test_vmixing>

Hossan
Posts: 8
Joined: May 20th, 2019, 4:53 pm
Registered HYSPLIT User: Yes

Re: Mixing Height for Back Trajectory

Post by Hossan » June 11th, 2019, 2:26 pm

Hi Christopher,

I really appreciate your time and help. Thank you so much.

I use windows based HYSPLIT. Could you please help me to run vmixing in windows?

Also, refer to my initial question: Even if there is 1-minute extra timestep, why mixing depth is varying for different trajectory height for the exact same location and time (attached picture)?

Thank you so much

Iqbal
Attachments
Capture.PNG

christopher.loughner
Posts: 17
Joined: August 15th, 2017, 3:59 pm
Registered HYSPLIT User: No

Re: Mixing Height for Back Trajectory

Post by christopher.loughner » June 13th, 2019, 10:21 am

Hi,

You can run vmixing in a command shell (i.e., not the gui). To open a command shell in windows, type "cmd" (without the quotes) in the windows search bar. Then move to the directory with your CONTROL and SETUP.CFG files (something like this: cd C:\test_vmixing) and execute the vmixing command (..\hysplit4\exec\vmixing.exe -s2 -t2). See my previous reply.

For the initial time, the output file is writing out the initial location, but the mixing depth at a different location. That is why the output shows a different mixing depth at the same initial location.

Chris

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