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Long simulation time. Wrong configurations?

Posted: February 27th, 2021, 10:21 pm
by hlbutterfly
Dear all,

I am doing a very simple concentration simulation with Hysplit. I have constant emissions from a single point source and the simulation duration is a week. I am driving the simulation using the HRRR data. I am generating min-by-min simulated concentrations at roughly 100 m x 100 m grid cell for a 5km x 5km domain. No chemistry, no deposition, very simple configuration. I am running Hysplit in pure puff mode and turn off puff split. The problem that I have is this simple simulation takes a hour or so to complete, whereas same simulation only takes about 10 min with Calpuff. So I am wondering what is causing this long simulation time with Hysplit. Is there any stupid mistake with my configuration?

One potential reason that I think may be related to the definition of the simulation domain. My interested domain is quite small, roughly 5 km x 5 km. How can I specify in Hysplit that when a released puff hits the boundary of this domain, it will be dropped from further simulation? Puff is released at every time step (1 min in my case). I am wondering is it because Hysplit is simulation lots of old puffs as the simulation goes on that is causing the long simulation time?

Thank you very much!

Re: Long simulation time. Wrong configurations?

Posted: March 18th, 2021, 1:01 pm
by christopher.loughner
Puffs will continue to be simulated with HYSPLIT if it is outside of the concentration domain, but within the meteorological domain in case the puff is re-circulated back into the concentration domain. If you would like HYSPLIT to not simulate the transport of this puff after it is transported outside of a certain domain, then you can create a smaller meteorological ARL file using the xtrct_grid utility program that only covers your area of interest. xtrct_grid will extract a subgrid of a meteorological ARL file based on a user defined latitude and longitude. To run, from your working directory, type: ../exec/xtrct_grid and then follow the user prompts.