Hysplit options related to horizontal/vertical dispersion
Posted: July 28th, 2021, 4:37 am
Dear all,
I am doing a very simple CH4 concentration simulation from a single point continuous source, using both pure puff (initd=1) and hybrid (initd=3) mode and HRRR met. data. The simulation last for an hour and with the hybrid mode I am using 15000 particles in total. I am using mostly default parameters. However, the vertical and horizontal dispersion results seem unreasonable in the following aspects:
(1) The horizontal spread is much bigger than the same simulation performed with calpuff or observation.
About ~200m downwind the source, the sigma y of the plume calculated from Hysplit is about 80 m while Calpuff's results and observations suggest a sigma y of only 8~9m.
(2) Vertical dispersion seems sudden.
I am seeing weird Hysplit results vertically during the daytime. For instance, during the time day, the concentration gets dispersed vertically almost instantaneously. Calpuff seems to give more reasonable and smooth vertical dispersion.
There seems to be several configurations that are related to the vertical mixing, for example, kmix0, kblt, kzmix, etc. but I am not sure which one or ones are important. Can anyone suggests which options or parameters that I should pay attention to, with respect to dispersion? I am attaching my CONTROL and SETUP.CFG file for reference. Is there anything wrong with my settings?
Thank you very much!
I am doing a very simple CH4 concentration simulation from a single point continuous source, using both pure puff (initd=1) and hybrid (initd=3) mode and HRRR met. data. The simulation last for an hour and with the hybrid mode I am using 15000 particles in total. I am using mostly default parameters. However, the vertical and horizontal dispersion results seem unreasonable in the following aspects:
(1) The horizontal spread is much bigger than the same simulation performed with calpuff or observation.
About ~200m downwind the source, the sigma y of the plume calculated from Hysplit is about 80 m while Calpuff's results and observations suggest a sigma y of only 8~9m.
(2) Vertical dispersion seems sudden.
I am seeing weird Hysplit results vertically during the daytime. For instance, during the time day, the concentration gets dispersed vertically almost instantaneously. Calpuff seems to give more reasonable and smooth vertical dispersion.
There seems to be several configurations that are related to the vertical mixing, for example, kmix0, kblt, kzmix, etc. but I am not sure which one or ones are important. Can anyone suggests which options or parameters that I should pay attention to, with respect to dispersion? I am attaching my CONTROL and SETUP.CFG file for reference. Is there anything wrong with my settings?
Thank you very much!