# CMAQ **URL:** https://forum.cmascenter.org/c/cmaq/7.md [Latest](https://forum.cmascenter.org/latest.md) · [Categories](https://forum.cmascenter.org/categories.md) · [Tags](https://forum.cmascenter.org/tags.md) --- ## [About the CMAQ category](https://forum.cmascenter.org/t/about-the-cmaq-category/20)
**Author:** [@lizadams](https://forum.cmascenter.org/u/lizadams)\ **Replies:** 0\ **Last updated:** [May 22, 2023, 4:00am UTC](https://forum.cmascenter.org/t/about-the-cmaq-category/20 "2023-05-22T04:00:00Z")
Need help running CMAQ? Search the topics posted here, and/or submit a new one to get help from others! PLEASE READ before posting --- ## [CB6 mechanism regarding Semi-volatile POA](https://forum.cmascenter.org/t/cb6-mechanism-regarding-semi-volatile-poa/6265)
**Author:** [@kkkghs0828](https://forum.cmascenter.org/u/kkkghs0828)\ **Replies:** 13\ **Last updated:** [September 24, 2026, 5:50pm UTC](https://forum.cmascenter.org/t/cb6-mechanism-regarding-semi-volatile-poa/6265 "2026-09-24T17:50:21Z")
Hi Everyone, I have questions about the treatment of semi-volatile POA in the CMAQ\_DESID file. ! Gas Species : VLVPO1 VSVPO1 VSVPO2 VSVPO3 VIVPO1 ! Particle Species : ALVPO1 ASVPO1 ASVPO2 ASVPO3 AIVPO1 ! C\* (µg … --- ## [Problem reading smk\_merge\_dates](https://forum.cmascenter.org/t/problem-reading-smk-merge-dates/6275)
**Author:** [@DLyder](https://forum.cmascenter.org/u/DLyder)\ **Replies:** 1\ **Last updated:** [September 14, 2026, 8:07pm UTC](https://forum.cmascenter.org/t/problem-reading-smk-merge-dates/6275 "2026-09-14T20:07:05Z")
Hello! I am trying to run CMAQ 5.5.0.3 to process some stack sources that were created using the mwdss representative date option in SMOKE 5.1. I have included detailed information for the ptnonipm sector. The CCTM scri… --- ## [CB6 mechanism regarding SULF and ASO4](https://forum.cmascenter.org/t/cb6-mechanism-regarding-sulf-and-aso4/6264)
**Author:** [@kkkghs0828](https://forum.cmascenter.org/u/kkkghs0828)\ **Replies:** 4\ **Last updated:** [September 9, 2026, 7:06pm UTC](https://forum.cmascenter.org/t/cb6-mechanism-regarding-sulf-and-aso4/6264 "2026-09-09T19:06:08Z")
Hello everyone, I have a question about the CB6r5 mechanism, specifically regarding SULF and ASO4. 'EVERYWHERE', 'ALL', 'SULF', 'SULF', 'GAS', 0., 'UNIT', 'a', 'EVERYWHERE', 'ALL', 'SULF', 'ASO4', 'FINE', 1., 'MASS', … --- ## [CLDS PA outputs all zero?](https://forum.cmascenter.org/t/clds-pa-outputs-all-zero/6250)
**Author:** [@xuan](https://forum.cmascenter.org/u/xuan)\ **Replies:** 2\ **Last updated:** [August 13, 2026, 9:18am UTC](https://forum.cmascenter.org/t/clds-pa-outputs-all-zero/6250 "2026-08-13T09:18:18Z")
Dear all, I am running CMAQv5.5 with the Process Analysis ¶ module enabled. I am analyzing the output for a single grid cell, and I find that the following cloud‑related process variables (CLDS\_ASO4I, CLDS\_ASO4J, CLDS\_O… --- ## [Disabling Plume Rise for Fire Sources from EQUATES in CMAQ 5.5](https://forum.cmascenter.org/t/disabling-plume-rise-for-fire-sources-from-equates-in-cmaq-5-5/6256)
**Author:** [@amirdudu](https://forum.cmascenter.org/u/amirdudu)\ **Replies:** 2\ **Last updated:** [July 22, 2026, 6:13pm UTC](https://forum.cmascenter.org/t/disabling-plume-rise-for-fire-sources-from-equates-in-cmaq-5-5/6256 "2026-07-22T18:13:03Z")
Hello Everyone, I want to run CMAQ 5.5 with EQUATES dataset. For this particular simulation that I am doing, I need to disable plumerise for all the fire sources. I was thinking about turning all the HFLUX values in the… --- ## [NOx underestimation in CMAQ (v5.5)](https://forum.cmascenter.org/t/nox-underestimation-in-cmaq-v5-5/6240)
**Author:** [@ganghan2000](https://forum.cmascenter.org/u/ganghan2000)\ **Replies:** 5\ **Last updated:** [June 19, 2026, 1:52pm UTC](https://forum.cmascenter.org/t/nox-underestimation-in-cmaq-v5-5/6240 "2026-06-19T13:52:45Z")
Hello, I have a problem with the NOx concentration in the CMAQ simulation. When I simulated the CMAQ, the NOx concentration was significantly underestimated. Initially, I thought the emission might be the problem, … --- ## [Process analysis confusion: VDIF and EMIS for NOX?](https://forum.cmascenter.org/t/process-analysis-confusion-vdif-and-emis-for-nox/6230)
**Author:** [@asouri](https://forum.cmascenter.org/u/asouri)\ **Replies:** 3\ **Last updated:** [June 15, 2026, 2:08pm UTC](https://forum.cmascenter.org/t/process-analysis-confusion-vdif-and-emis-for-nox/6230 "2026-06-15T14:08:23Z")
Describe your issue in detail Hello, I’m trying to investigate the physicochemical processes (transport, emissions, deposition, chemistry, …) related to the formation and loss of NOx using the process analysis routine. … --- ## [Undefined Dry Deposition velocity in m3dry for innermost domain of nested simulation](https://forum.cmascenter.org/t/undefined-dry-deposition-velocity-in-m3dry-for-innermost-domain-of-nested-simulation/5880)
**Author:** [@flaviaribeiro](https://forum.cmascenter.org/u/flaviaribeiro)\ **Replies:** 7\ **Last updated:** [June 2, 2026, 3:53pm UTC](https://forum.cmascenter.org/t/undefined-dry-deposition-velocity-in-m3dry-for-innermost-domain-of-nested-simulation/5880 "2026-06-02T15:53:48Z")
Hello! I’ve ran into an error that I’m not finding the solution or a similar post. I’ve ran CMAQ for a coarse domain and it ran fine (or so I think, because I didn’t get any errors and I looked at the output and seemed f… --- ## [Interpretation of CMAQ Process Analysis values between scenarios](https://forum.cmascenter.org/t/interpretation-of-cmaq-process-analysis-values-between-scenarios/6202)
**Author:** [@Hyeonseo](https://forum.cmascenter.org/u/Hyeonseo)\ **Replies:** 1\ **Last updated:** [May 13, 2026, 2:34pm UTC](https://forum.cmascenter.org/t/interpretation-of-cmaq-process-analysis-values-between-scenarios/6202 "2026-05-13T14:34:38Z")
I am currently using Process Analysis in CMAQ version 5.3.2 to obtain IPR contribution values. In my study, I adjusted BVOC emissions during a heatwave episode and compared the resulting changes in ozone concentrations b… --- ## [Inquiry Regarding the Underestimation of NH4 in CMAQ PM2.5 Simulations](https://forum.cmascenter.org/t/inquiry-regarding-the-underestimation-of-nh4-in-cmaq-pm2-5-simulations/6193)
**Author:** [@GuoXianhao](https://forum.cmascenter.org/u/GuoXianhao)\ **Replies:** 1\ **Last updated:** [May 12, 2026, 5:50pm UTC](https://forum.cmascenter.org/t/inquiry-regarding-the-underestimation-of-nh4-in-cmaq-pm2-5-simulations/6193 "2026-05-12T17:50:50Z")
Dear Sir/Madam, I am writing to inquire about the NH4 component of PM2.5 in CMAQ v5.3 simulations. My simulation domain covers mainland China, and the simulation period is March to April, when dust emissions are relati… --- ## [Estimating VOCr from CMAQv5.5 CRACMMv2](https://forum.cmascenter.org/t/estimating-vocr-from-cmaqv5-5-cracmmv2/6190)
**Author:** [@hosok004](https://forum.cmascenter.org/u/hosok004)\ **Replies:** 1\ **Last updated:** [May 7, 2026, 1:43pm UTC](https://forum.cmascenter.org/t/estimating-vocr-from-cmaqv5-5-cracmmv2/6190 "2026-05-07T13:43:15Z")
Hello, I’ve run some CMAQv5.5 CRACCMv2 simulations and was interested in using the output files to estimate VOC reactivity and OH lifetime. To get VOCr, would it be sufficient to take a sum similar to the VROC calculati… --- ## [Possible issues with mercury bidirectional exchange under STAGE in CMAQ v5.5](https://forum.cmascenter.org/t/possible-issues-with-mercury-bidirectional-exchange-under-stage-in-cmaq-v5-5/6184)
**Author:** [@yanzcj](https://forum.cmascenter.org/u/yanzcj)\ **Replies:** 1\ **Last updated:** [April 30, 2026, 3:36pm UTC](https://forum.cmascenter.org/t/possible-issues-with-mercury-bidirectional-exchange-under-stage-in-cmaq-v5-5/6184 "2026-04-30T15:36:16Z")
Hi, I am a master’s student using CMAQ v5.5 with the STAGE deposition option and mercury bidirectional exchange. While tracing the STAGE mercury code, I found two places that seem to be original coding issues rather tha… --- ## [CCTM run error about AQCHEM on PE 000](https://forum.cmascenter.org/t/cctm-run-error-about-aqchem-on-pe-000/5509)
**Author:** [@yan2024](https://forum.cmascenter.org/u/yan2024)\ **Replies:** 11\ **Last updated:** [April 21, 2026, 12:26am UTC](https://forum.cmascenter.org/t/cctm-run-error-about-aqchem-on-pe-000/5509 "2026-04-21T00:26:13Z")
Hi teachers, I am currently encountering some issues while running CMAQ and I cant find similar situation from earlier post. For reaching out for your guidance I have attached the error log and my run script for your re… --- ## [Question about origin and meaning of legacy static desert-fraction values in lus\_data\_module.F (CMAQ v5.3.1)](https://forum.cmascenter.org/t/question-about-origin-and-meaning-of-legacy-static-desert-fraction-values-in-lus-data-module-f-cmaq-v5-3-1/6180)
**Author:** [@THosler](https://forum.cmascenter.org/u/THosler)\ **Replies:** 0\ **Last updated:** [April 8, 2026, 12:12am UTC](https://forum.cmascenter.org/t/question-about-origin-and-meaning-of-legacy-static-desert-fraction-values-in-lus-data-module-f-cmaq-v5-3-1/6180 "2026-04-08T00:12:52Z")
Hello, I am using the CMAQ v5.3.1 windblown dust physics in an offline framework at much higher spatial resolution than a traditional CMAQ application, and I am trying to better understand the origin and intended interp… --- ## [My CCTM always gets stuck in an infinite loop just as it is about to reach 3:00](https://forum.cmascenter.org/t/my-cctm-always-gets-stuck-in-an-infinite-loop-just-as-it-is-about-to-reach-3-00/6165)
**Author:** [@weir](https://forum.cmascenter.org/u/weir)\ **Replies:** 3\ **Last updated:** [April 6, 2026, 8:12pm UTC](https://forum.cmascenter.org/t/my-cctm-always-gets-stuck-in-an-infinite-loop-just-as-it-is-about-to-reach-3-00/6165 "2026-04-06T20:12:08Z")
I encountered no issues when running the first layer (d01) of CCTM, but when I run the second layer (d02), it always falls into an infinite loop just before reaching 3:00. When I set setenv CTM\_MAXSYNC=120 , it gets stuc… --- ## [2026 NADP TDep Webinar Presentation on Modeling Ammonia Deposition](https://forum.cmascenter.org/t/2026-nadp-tdep-webinar-presentation-on-modeling-ammonia-deposition/6151)
**Author:** [@foley.kristen](https://forum.cmascenter.org/u/foley.kristen)\ **Replies:** 2\ **Last updated:** [April 2, 2026, 2:17pm UTC](https://forum.cmascenter.org/t/2026-nadp-tdep-webinar-presentation-on-modeling-ammonia-deposition/6151 "2026-04-02T14:17:54Z")
2026 TDep Webinar Series NADP’s Total Deposition Science Committee invites you to our inaugural TDep Webinar Series presentation: Tuesday, March 3rd, 12-1pm EST Modeling ammonia deposition to sensitive ecosystems: res… --- ## [CRACMM2 ICON,BCON Error](https://forum.cmascenter.org/t/cracmm2-icon-bcon-error/6175)
**Author:** [@Heomin](https://forum.cmascenter.org/u/Heomin)\ **Replies:** 2\ **Last updated:** [March 31, 2026, 2:03pm UTC](https://forum.cmascenter.org/t/cracmm2-icon-bcon-error/6175 "2026-03-31T14:03:58Z")
Hello, I am trying to run a CMAQ simulation using the CRACMM2 mechanism. Before starting the simulation, I attempted to generate the ICON and BCON input files. To do this, I used map2mech to convert existing Hemispheri… --- ## [PM25 OUTPUT ERROR about CMAQ5.3.3-ISAM](https://forum.cmascenter.org/t/pm25-output-error-about-cmaq5-3-3-isam/6159)
**Author:** [@sher](https://forum.cmascenter.org/u/sher)\ **Replies:** 1\ **Last updated:** [March 17, 2026, 9:15pm UTC](https://forum.cmascenter.org/t/pm25-output-error-about-cmaq5-3-3-isam/6159 "2026-03-17T21:15:08Z")
Hello, I am using CMAQ\_ISAM v5.3.3 and have tagged all seven species related to PM2.5. When analyzing the PM2.5 data from the CMAQ-ISAM output, I found an issue: the total concentration of tagged species accounts for onl… --- ## [CMAQ\_Control\_DESID\_cracmmv2 2022 file version vs default](https://forum.cmascenter.org/t/cmaq-control-desid-cracmmv2-2022-file-version-vs-default/6158)
**Author:** [@hosok004](https://forum.cmascenter.org/u/hosok004)\ **Replies:** 2\ **Last updated:** [March 6, 2026, 6:12pm UTC](https://forum.cmascenter.org/t/cmaq-control-desid-cracmmv2-2022-file-version-vs-default/6158 "2026-03-06T18:12:29Z")
Hello, I was looking through the cmaq-12us1-cracmm2-modeling-platform-2022 data repository in the CMAS ware house (https://dataverse.unc.edu/dataset.xhtml?persistentId=doi:10.15139/S3/BDLBTW) and I noticed that the 2022… --- ## [CMAQ-ADJ (v5.0.2) compatibility with WRF Hybrid Vertical Coordinate without rerunning WRF](https://forum.cmascenter.org/t/cmaq-adj-v5-0-2-compatibility-with-wrf-hybrid-vertical-coordinate-without-rerunning-wrf/6147)
**Author:** [@derek](https://forum.cmascenter.org/u/derek)\ **Replies:** 4\ **Last updated:** [February 21, 2026, 3:52pm UTC](https://forum.cmascenter.org/t/cmaq-adj-v5-0-2-compatibility-with-wrf-hybrid-vertical-coordinate-without-rerunning-wrf/6147 "2026-02-21T15:52:59Z")
Hello CMAQ community, I am currently working with CMAQ-Adjoint (CMAQ-ADJ v5.0.2) for inverse modeling and sensitivity analysis. However, I am encountering a vertical coordinate compatibility issue when processing meteor… --- ## [Adjust the HNO₃ dry deposition](https://forum.cmascenter.org/t/adjust-the-hno-dry-deposition/6148)
**Author:** [@XIAO](https://forum.cmascenter.org/u/XIAO)\ **Replies:** 1\ **Last updated:** [February 9, 2026, 8:08pm UTC](https://forum.cmascenter.org/t/adjust-the-hno-dry-deposition/6148 "2026-02-09T20:08:31Z")
I am using CMAQ v5.3.1 with the M3Dry dry deposition scheme. I would like to modify the dry deposition velocity of gaseous HNO₃ for a sensitivity experiment. May I ask which part of the CCTM source code controls HNO₃ dry… --- ## [Question about CRACMM2 species properties](https://forum.cmascenter.org/t/question-about-cracmm2-species-properties/6144)
**Author:** [@afernandez](https://forum.cmascenter.org/u/afernandez)\ **Replies:** 3\ **Last updated:** [February 4, 2026, 1:15pm UTC](https://forum.cmascenter.org/t/question-about-cracmm2-species-properties/6144 "2026-02-04T13:15:30Z")
Hello, Q1 - I have some emission rates for propane, alkanes (with 4 or more carbons) and propene. Looking at the CRACMMv2.0 Emissions Mapping (3/17/2025), the first 2 should be evaluated based on whether they’re slow, i… --- ## [Is All G0 need to be calculated in CALCACT?](https://forum.cmascenter.org/t/is-all-g0-need-to-be-calculated-in-calcact/6122)
**Author:** [@rzbbc](https://forum.cmascenter.org/u/rzbbc)\ **Replies:** 3\ **Last updated:** [January 19, 2026, 10:57am UTC](https://forum.cmascenter.org/t/is-all-g0-need-to-be-calculated-in-calcact/6122 "2026-01-19T10:57:18Z")
Hi, there :blush: I have been optimize AERO for a while, and my concentration is ISOROPIA. After some research upon the code and some ISOROPIA-II paper, some questions occurs and these question may become optimize poin… --- ## [How to output particulate water content and pH in CMAQ v5.5](https://forum.cmascenter.org/t/how-to-output-particulate-water-content-and-ph-in-cmaq-v5-5/6124)
**Author:** [@hosok004](https://forum.cmascenter.org/u/hosok004)\ **Replies:** 3\ **Last updated:** [January 15, 2026, 2:55pm UTC](https://forum.cmascenter.org/t/how-to-output-particulate-water-content-and-ph-in-cmaq-v5-5/6124 "2026-01-15T14:55:16Z")
Hello, I am running a simulation with the cracmm2 mechanism in CMAQv5.5 and I was wondering if there was a way to output the water content and pH of PM2.5 species using the CCTM files. I found a section in the SpecDef\_Co… --- ## [Can CMAQ only run with less than a thousand processors?](https://forum.cmascenter.org/t/can-cmaq-only-run-with-less-than-a-thousand-processors/6118)
**Author:** [@vkrmravi](https://forum.cmascenter.org/u/vkrmravi)\ **Replies:** 2\ **Last updated:** [January 6, 2026, 11:09pm UTC](https://forum.cmascenter.org/t/can-cmaq-only-run-with-less-than-a-thousand-processors/6118 "2026-01-06T23:09:43Z")
Hello I am running CMAQv5.5 built using gcc on a cray machine. I’m testing the optimal configuration (e.g., domain decomposition for my HPC), for CONUS 12US1 domain using 2022v1 EMP data. In the process I set up CMAQ to… --- ## [How does the CMAQ model simulate the increase in PM concentration caused by sandstorms](https://forum.cmascenter.org/t/how-does-the-cmaq-model-simulate-the-increase-in-pm-concentration-caused-by-sandstorms/5516)
**Author:** [@xia](https://forum.cmascenter.org/u/xia)\ **Replies:** 5\ **Last updated:** [January 4, 2026, 11:45am UTC](https://forum.cmascenter.org/t/how-does-the-cmaq-model-simulate-the-increase-in-pm-concentration-caused-by-sandstorms/5516 "2026-01-04T11:45:19Z")
Hi everyone, I have recently been using CMAQv5.4. My simulation domain is located in Asia. I found that the results of CMAQ did not simulate the increase in PM concentration caused by sandstorms. I attempted to set the… --- ## [Where is hot spot in cloud?](https://forum.cmascenter.org/t/where-is-hot-spot-in-cloud/6082)
**Author:** [@rzbbc](https://forum.cmascenter.org/u/rzbbc)\ **Replies:** 7\ **Last updated:** [December 22, 2025, 1:36pm UTC](https://forum.cmascenter.org/t/where-is-hot-spot-in-cloud/6082 "2025-12-22T13:36:57Z")
Hi there~ :blush: Thank you for watching this post~ I’m trying to optimize cldproc recently, and i locate an hotspot in subroutine RESCLD. After some code insert and test, i realize that there exist an big load unbala… --- ## [CMAQ-PFAS CCTM/src](https://forum.cmascenter.org/t/cmaq-pfas-cctm-src/6035)
**Author:** [@nimaaandm](https://forum.cmascenter.org/u/nimaaandm)\ **Replies:** 5\ **Last updated:** [December 18, 2025, 11:04pm UTC](https://forum.cmascenter.org/t/cmaq-pfas-cctm-src/6035 "2025-12-18T23:04:07Z")
Hi everyone, I am seeing some of you referring to CMAQ-PFAS source files on github but I cannot find that. I wonder if there is a CMAQ-PFAS model on github with CCTM/src files open to public. Please comment. Thanks, N… --- ## [Tolerance for negative emissions in the DESID module](https://forum.cmascenter.org/t/tolerance-for-negative-emissions-in-the-desid-module/5241)
**Author:** [@bkoo](https://forum.cmascenter.org/u/bkoo)\ **Replies:** 3\ **Last updated:** [December 18, 2025, 10:23pm UTC](https://forum.cmascenter.org/t/tolerance-for-negative-emissions-in-the-desid-module/5241 "2025-12-18T22:23:28Z")
I was trying to do a zero-out CMAQ (v5.4) run where emissions from a source sector were eliminated. I was subtracting the source sector emissions from merged emissions at runtime using the DESID module. The run failed w… [Next page](https://forum.cmascenter.org/c/cmaq/7.md?page=1)