Hi, everyone. I have a few questions in PA of CMAQ 5.3.3. According to the Users Guide of CMAQ, AERO processes consist mainly of “COAG”, “COND”, “GROW” and “NPF”. I set CTM_PROCAN to Y when I run CCTM. Then “COAG_NUMATKN”, “COND_NUMATKN”, “GROW_NUMATKN” and “NPF_NUMATKN” are found in the PA file, but the unit of these four variables is “m-3”. I don’t know how to extract the contribution of the AERO process to PM2.5. Looking forward your help, thanks.
Hello,
The unit for the aerosol number concentration change in response to individual processes is a little bit tricky. We use the “m-3” label, and the numerator is implied to be “number of particles”.
If you want the contributions of AERO to total PM2.5, then you need to sum up the individual process changes for aerosol species that are part of PM2.5. This will be a little bit different depending on the mechanism you have chosen, but you can use the Species Definition files provided in the CMAQ repo to reconstruct this value. For example, this Species Definition file shows how to process output using the cb6r3 mechanism: CMAQ/CCTM/src/MECHS/cb6r3_ae7_aq/SpecDef_cb6r3_ae7_aq.txt at 5.3.3 · USEPA/CMAQ · GitHub
Best wishes,
Ben Murphy
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