Question about ptfire inline mode

SMOKE
1

I am using 2016v1 platform to run daily ptfire emission with inline mode on. I notice the daily stack heights are all negative infinities. I am wondering is it due to the model considers the stack height for the fires are all at the surface or I made any wrong with the simulation? The model ran successfully without any errors.

Thanks,
K

2

Plume rise is calculated based on the heat flux and meteorological parameters rather than from emissions stack parameters. There are some dummy stack parameter values in the inventory but SMOKE doesn’t pass these through to the stack groups file.

3

Thanks for response. I am wondering the difference between ptfire2d and ptfire3d. It seems like ptfire3d simulation provide emissions from upper layer. I am curious how this model provide verticle emission distribution.

Thanks,
K

4

and also, how could I check the plume rise include plume height in the simulation output?

5

Good morning, there are multiple ways to run ptfire through SMOKE. Would you mind sharing your SMOKE script to the forum? Typically the ptfire3d provides emissions from the upper layers but may not contain base layer emissions depending on the settings.

SMOKE uses a set of plume rise calculations to determine buoyancy flux from heat flux, described in the SMOKE manual:
https://www.cmascenter.org/smoke/documentation/5.0/html/ch04s06.html#sect_programs_laypoint_plume_rise_fires
The resulting buoyancy flux is then used in a modified Briggs equation to calculate plume rise.

7

Thank you, James. I am using the script provided in the 2016v1 platform and modified the inventory and basic settings to simulate the emissions from 2018. I am wondering if this simulation provides the emission of different vertical layers and how it works. At the same time, I wonder if it is possible to estimate the vertical height (stack height) in turning on the in-line mode.
Annual_ptfire_daily_12US1_2017gb_17j.csh (7.2 KB)
Thanks for your help.
Best,
K

8

It is possible to get a report of emissions by layer using smkreport and the “BY LAYER” option in the repconfig. More information is available in the repconfig documentation:
https://www.cmascenter.org/smoke/documentation/5.0/html/ch05s03s03.html#d0e26033
This type of report only works when you run laypoint to get 3D gridded files rather than producing in-line emissions files.

When using in-line fire emissions CMAQ uses the heat flux from the stack groups file to calculate the plume rise. CMAQ applies the same equations referenced above in the SMOKE documentation to estimate the plume rise from fires. Are you trying to determine the top of the plume? This is an internal variable in the plume rise calculations but it is not retained.

9

Thanks for response. But once I using inline mode for fire sources, no matter I am using 2d or 3d, the value “stack height” in the daily stack group file are all negative. I turned the inline mode as “only” in the script. Did I run correctly or how could I run the model so that SMOKE can provide stack height for me?

10

Based on your description and the earlier script that you provided it looks like you ran the script correctly. Could you please verify what you mean by “stack height” for fire sources? Are you looking for the initial height of the plume?

11

Thanks for your response, James. I am trying to grab the stack height of the ptfire emission. I am using same script but with the inline mode as only. The model gave me daily stack group and inline mole files. I check the variable “STKHT” in the stack group file and found that they are all negative values. This value in the sources other than fires are positive with reasonable value. I am wondering how can I check the vertical emission rate as other point source.

12

Regardless of what is in the inventory SMOKE internally resets the STKHT value for fires first to the negative value that you see in the stack groups file and then to 0 when calculating plume rise. The emissions are assumed to be released in the base layer as the fire is occurring near the ground.

The buoyancy flux used for estimating plume rise in CMAQ is calculated from the heat flux of the fire rather than the stack parameters. I’ll refer back again to the equations in the SMOKE documentation:
https://www.cmascenter.org/smoke/documentation/5.0/html/ch04s06.html#sect_programs_laypoint_plume_rise_fires

14

Thansk for responses, James! Now I might go back to the previous question about the vertical distribution of the emission in ptfire3D. I noticed that there are some fire points that have emissions other than the base layer, I am wondering how the model distributes emissions to different vertical layers.