Turning off emissions sources in CMAQ 5.3

CMAQ
1

Hello,

I am working on using the Windblown Dust Model within CMAQ to study to particulate matter emissions. I am using CMAQ version 5.3.1 and I would like to know if it is possible to have the CCTM not take into account any emissions besides those created inline by the windblown dust model? If this is possible would I still have to have SMOKE input files?

Lawless

2

@lawless – I believe the easiest way to achieve what you are describing is to turn off all the emissions sources other than windblown dust.

setenv N_EMIS_GR 0
setenv N_EMIS_PT 0
setenv CTM_EMISCHK N
setenv CTM_BIOGEMIS N
setenv CTM_LTNG_NO N
setenv CTM_OCEAN_CHEM N
setenv CTM_WB_DUST Y
3

Thank you for the advice I am running that with benchmark right now.

Follow up to that though, would it be possible to use the same SMOKE files from the benchmark with other runs if all the emissions are turned off? I am not too familiar with SMOKE and how to generate files with it.

4

I am not sure if I understand the question, but if you are not reading the emissions input files, then it does not matter whether they even exist.

5

My understanding is that SMOKE input files are required according to the CMAQ Users Guide

I just have had to learn WRF and CMAQ for masters and I am hoping not to add another program to that haha.

6

Emissions inputs are required if you want to do a “real” simulation. But they can be turned off for model development purposes, such as testing advection from initial and boundary conditions.

7

Just so I am following correctly. If I zero out all emissions as you described in your first reply, I shouldnt have to have any SMOKE input files?

8

“Zeroing out” emissions is conceptually different. That involves reading in emissions files, then setting the emissions for certain species, sources, regions, or whatever to 0. That is achievable using the new DESID feature.

But if you want no gridded or in-line point source emissions whatsoever, then it is easier to set the corresponding environment variables (listed above) to 0.

It is confusing to refer to “SMOKE input files” – that normally means input files for running SMOKE rather than the outputs of SMOKE, which are then used as inputs for CMAQ.

9

Sorry forgive my ignorance I am still trying to learn all this haha.

This information has been super helpful, thank you!