# Identifying MCIP Variables Related to PM2.5 Changes Under m3dry Scheme **URL:** \ **Category:** CMAQ\ **Created:** [March 28, 2025, 3:04pm UTC](https://forum.cmascenter.org/t/identifying-mcip-variables-related-to-pm2-5-changes-under-m3dry-scheme/5693 "2025-03-28T15:04:20Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![yan2024](https://avatars.discourse-cdn.com/v4/letter/y/59ef9b/32.png) [@yan2024](https://forum.cmascenter.org/u/yan2024)\ **Post date:** [March 28, 2025, 3:04pm UTC](https://forum.cmascenter.org/t/identifying-mcip-variables-related-to-pm2-5-changes-under-m3dry-scheme/5693/1 "2025-03-28T15:04:20Z")
Hi teachers, I’m currently running CMAQ with the m3dry dry deposition scheme. I’d like to extract certain meteorological and geophysical variables from the MCIP output files that are relevant to PM2.5 changes through processes such as dry deposition. My goal is to analyze the relationship between these variables and the PM2.5 distribution from the CCTM output. Could you please confirm which variables are involved in this process? Are they the ones in the attached screenshot? Also, is there any specific guidance on choosing between dry and wet deposition schemes? How should one determine which scheme is more appropriate for a given case? ![image](https://canada1.discourse-cdn.com/flex027/uploads/cmas/original/2X/7/7e30919f3b43d60801ec0d5b90110b2fd757b6bf.png) ---
**Author:** ![slfarrell](https://avatars.discourse-cdn.com/v4/letter/s/e9bcb4/32.png) [@slfarrell](https://forum.cmascenter.org/u/slfarrell)\ **Post date:** [May 7, 2025, 5:11pm UTC](https://forum.cmascenter.org/t/identifying-mcip-variables-related-to-pm2-5-changes-under-m3dry-scheme/5693/2 "2025-05-07T17:11:49Z")
Hi Yan, These variables should be in the METCRO\_2D files. Granted, these are inputs to CMAQ and therefore they could impact modeled PM2.5 concentrations but not the other way around (unless you use WRF-CMAQ with radiative feedbacks turned on). If you are interested in how much of each PM2.5 species is being deposited (both wet and dry), you would find those outputs in your CCTM\_WETDEP1 and CCTM\_DRYDEP output files. ---
**Author:** ![slfarrell](https://avatars.discourse-cdn.com/v4/letter/s/e9bcb4/32.png) [@slfarrell](https://forum.cmascenter.org/u/slfarrell)\ **Post date:** [May 7, 2025, 5:13pm UTC](https://forum.cmascenter.org/t/identifying-mcip-variables-related-to-pm2-5-changes-under-m3dry-scheme/5693/3 "2025-05-07T17:13:16Z")
Descriptions of each of these variables can be found here: [CMAQ/DOCS/Users\_Guide/CMAQ\_UG\_ch04\_model\_inputs.md at main · USEPA/CMAQ · GitHub](https://github.com/USEPA/CMAQ/blob/main/DOCS/Users_Guide/CMAQ_UG_ch04_model_inputs.md#met_cro_2d) ---
**Author:** ![yan2024](https://avatars.discourse-cdn.com/v4/letter/y/59ef9b/32.png) [@yan2024](https://forum.cmascenter.org/u/yan2024)\ **Post date:** [May 8, 2025, 3:59am UTC](https://forum.cmascenter.org/t/identifying-mcip-variables-related-to-pm2-5-changes-under-m3dry-scheme/5693/4 "2025-05-08T03:59:56Z")
Hi slfaarrell, thank you so much! ---
**Author:** ![lizadams](https://avatars.discourse-cdn.com/v4/letter/l/49beb7/32.png) [@lizadams](https://forum.cmascenter.org/u/lizadams)\ **Post date:** [May 19, 2025, 8:50pm UTC](https://forum.cmascenter.org/t/identifying-mcip-variables-related-to-pm2-5-changes-under-m3dry-scheme/5693/6 "2025-05-19T20:50:48Z")
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**Author:** ![system](https://canada1.discourse-cdn.com/flex027/uploads/cmas/original/1X/9a72c78e529465c3f1053af404e3033b0875428c.png) [@system](https://forum.cmascenter.org/u/system)\ **Post date:** [June 3, 2025, 1:19pm UTC](https://forum.cmascenter.org/t/identifying-mcip-variables-related-to-pm2-5-changes-under-m3dry-scheme/5693/7 "2025-06-03T13:19:21Z")
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