Convection

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klgo
Posts: 5
Joined: June 14th, 2021, 5:20 am
Registered HYSPLIT User: Yes

Convection

Post by klgo »

Pollutants might get redistributed vertically by deep and shallow convection. How can this be accounted for in HYSPLIT (relevant for both, trajectories and dispersion)?
alicec
Posts: 411
Joined: February 8th, 2016, 12:56 pm
Registered HYSPLIT User: Yes

Re: Convection

Post by alicec »

If CAPE (convective available potential energy) is available in the MET data set then HYSPLIT can utilize that.

https://www.ready.noaa.gov/hysplitusersguide/S640.htm

This is discussed in the advanced tutorial a bit a well.
https://www.ready.noaa.gov/documents/Tu ... _cape.html
christopher.loughner
Posts: 81
Joined: August 15th, 2017, 3:59 pm
Registered HYSPLIT User: No

Re: Convection

Post by christopher.loughner »

To have HYSPLIT simulate convection when CAPE exceeds a certain threshold, set CAPEMIN to a value larger than zero. Note that if you don't have CAPE in the met files, HYSPLIT will calculate for you for each grid cell, which will slow down your simulation.

To utilize HYSPLIT's extreme convection scheme, which simulates convective transport whenever CAPE is greater than zero, set CAPEMIN=-3. We don't recommend using this option to be used on its own. You may want to run with this option and in conjunction with a HYSPLIT simulation with no convection (CAPEMIN=-1) in order to bound the possible solution due to convection.

A bit advanced, but if you are familiar with WRF and run it with the Grell convection scheme, you can pass the Grell convective fluxes into HYSPLIT met input files using the arw2arl converter. You can then chose to run HYSPLIT using the Grell convective fluxes to with the setting CAPEMIN=-2.
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