Questions about PM2.5 calculation in CMAQv5.4 cb6r5AERO7 mechanism

Hi all,
I would like to ask a question directly associated with PM2.5 calculation in CMAQv5.4 cb6r5AERO7. While there is additional output file from CCTM under CMAQv5.4 that directly give PM related concentrations, there is not any details in COMBINE directory that descrbes how PM2.5 are calculated in CMAQv5.4 cb6r5AERO7 mechanism. For users who would like to conduct source attribution of PM2.5 with cb6r5AERO7 mechanism, we must know the equation for calculating PM2.5 and PM10 because CMAQv5.4-ISAM (CCTM_SA_ACONC file) does not directly output PM2.5 and PM10.
Is the equation calculating PM2.5 in cb6r5AE7 the same as cb6r3AE7 (which we could find the quation in COMBINE under CMAQv5.3.3)?
Moreover, may I ask how could we calculate speciated components of PM0.1 by CMAQv5.4-ISAM?

Any comments are highly appreciated!

@Ben_Murphy @hogrefe.christian @sergey


Hi Ryan,

Thanks for pointing this out. Yes, we should have connected some of these dots.

  1. In order to calculate PM2.5, you can use the same equations applicable in v5.3.3. The main thing to confirm is to make sure you have included all of the organic species.
  2. To get PM0.1, you can add “FPM01” to the ELMO interface and use that to multiply each component offline. However, it should be output by default to the ELMO file (i.e. when the string ‘DEFAULT’ is used.)
  3. In the future, we will expand the ELMO module to print PM2.5 (or PM0.1, etc) directly for ISAM sources. Will this largely solve your issue (eventually)?


1 Like

Hi Ben,
Thanks for this timely reply. All my questions are clearly addressed.
I apprecite your kind help!