# Post-processing **URL:** https://forum.cmascenter.org/c/cmaq/post-processing/12.md [Latest](https://forum.cmascenter.org/latest.md) · [Categories](https://forum.cmascenter.org/categories.md) · [Tags](https://forum.cmascenter.org/tags.md) --- ## [About the Post-processing category](https://forum.cmascenter.org/t/about-the-post-processing-category/33)
**Author:** [@lizadams](https://forum.cmascenter.org/u/lizadams)\ **Replies:** 0\ **Last updated:** [June 21, 2018, 10:17pm UTC](https://forum.cmascenter.org/t/about-the-post-processing-category/33 "2018-06-21T22:17:34Z")
For topics related to CMAQ post-processing tools and software (AMET, Python, R). --- ## [CMAQ5.5 sitecmp PM25\_TOT vs PM25\_FRM](https://forum.cmascenter.org/t/cmaq5-5-sitecmp-pm25-tot-vs-pm25-frm/6019)
**Author:** [@hosok004](https://forum.cmascenter.org/u/hosok004)\ **Replies:** 2\ **Last updated:** [September 29, 2025, 4:18pm UTC](https://forum.cmascenter.org/t/cmaq5-5-sitecmp-pm25-tot-vs-pm25-frm/6019 "2025-09-29T16:18:51Z")
Hello, I have a question related to the PM2.5 AQS method codes for sitecmp. From what I understand, AQS method code 88101 corresponds to PM2.5 Local Conditions, while 88502 corresponds to Acceptable PM2.5 AQI & Speciatio… --- ## [CMAQ5.5 sitecmp for Daily AQS PM2.5 Speciation](https://forum.cmascenter.org/t/cmaq5-5-sitecmp-for-daily-aqs-pm2-5-speciation/6017)
**Author:** [@hosok004](https://forum.cmascenter.org/u/hosok004)\ **Replies:** 2\ **Last updated:** [September 25, 2025, 4:14pm UTC](https://forum.cmascenter.org/t/cmaq5-5-sitecmp-for-daily-aqs-pm2-5-speciation/6017 "2025-09-25T16:14:30Z")
Hello, I am using sitecmp in CMAQ5.5 to compare my model results to the AQS daily values for 24-hr avg PM2.5 sharp cut-off species. For my inputs, I am using the AQS\_daily\_data\_2005 table from the AMET folder in the CMA… --- ## [Biogenic emissions using BIES](https://forum.cmascenter.org/t/biogenic-emissions-using-bies/5935)
**Author:** [@Sam](https://forum.cmascenter.org/u/Sam)\ **Replies:** 3\ **Last updated:** [July 25, 2025, 12:07am UTC](https://forum.cmascenter.org/t/biogenic-emissions-using-bies/5935 "2025-07-25T00:07:41Z")
I am using CMAQ 5.4 with ISAM for source apportionment. I used BIES for inline biogenic emissions but in the output, I am noticing that the biogenic emissions are very small. I am tracking POM in my ISAM control file for… --- ## [Abnormal pm2.5 numerical simulation results](https://forum.cmascenter.org/t/abnormal-pm2-5-numerical-simulation-results/5851)
**Author:** [@sher](https://forum.cmascenter.org/u/sher)\ **Replies:** 2\ **Last updated:** [June 17, 2025, 7:55am UTC](https://forum.cmascenter.org/t/abnormal-pm2-5-numerical-simulation-results/5851 "2025-06-17T07:55:39Z")
Hello, I simulated the concentration of PM with the CMAQ5.3.3. The simulation period is January 2020, and the simulation domain is North China, using the MEIC emission inventory data. The concentration of PM2.5 extracted… --- ## [How to calculate PM2.5 concentration from CMAQ output](https://forum.cmascenter.org/t/how-to-calculate-pm2-5-concentration-from-cmaq-output/5761)
**Author:** [@sher](https://forum.cmascenter.org/u/sher)\ **Replies:** 1\ **Last updated:** [April 23, 2025, 4:35pm UTC](https://forum.cmascenter.org/t/how-to-calculate-pm2-5-concentration-from-cmaq-output/5761 "2025-04-23T16:35:29Z")
Hi, I use CMAQ v5.3.3, and among the species I can find, there are PM25\_TOT and some PM25 components (such as PM25\_OC, PM25\_NO3, etc.). Regarding the information, I am using the cb6r3\_ae7 scheme, so the script SpecDef\_cb… --- ## [How to Combine CCTM for all layers?](https://forum.cmascenter.org/t/how-to-combine-cctm-for-all-layers/3699)
**Author:** [@ting](https://forum.cmascenter.org/u/ting)\ **Replies:** 6\ **Last updated:** [March 2, 2025, 11:08pm UTC](https://forum.cmascenter.org/t/how-to-combine-cctm-for-all-layers/3699 "2025-03-02T23:08:17Z")
Dear all, I’m using CMAQ-combine to process CMAQ output files, and I want to combine output all layers. In the Species definition file, I have changed ‘#layer 1’ to ‘!#layer 1’, but I only got 1 layer. How can I solve t… --- ## [Extract only specific layer](https://forum.cmascenter.org/t/extract-only-specific-layer/5426)
**Author:** [@kkkghs0828](https://forum.cmascenter.org/u/kkkghs0828)\ **Replies:** 4\ **Last updated:** [December 10, 2024, 1:44am UTC](https://forum.cmascenter.org/t/extract-only-specific-layer/5426 "2024-12-10T01:44:16Z")
Hi I have 35 layers CONC output file but I want to extract 1-15 layers only. Is there any other ways to extract 1-15 layers only? I am trying with combine or m3tool but I was not able to find the good method. --- ## [CONUS Canada Mexico landmask file](https://forum.cmascenter.org/t/conus-canada-mexico-landmask-file/5147)
**Author:** [@skunwar](https://forum.cmascenter.org/u/skunwar)\ **Replies:** 1\ **Last updated:** [August 14, 2024, 2:48pm UTC](https://forum.cmascenter.org/t/conus-canada-mexico-landmask-file/5147 "2024-08-14T14:48:39Z")
I was wondering if there exists a country-specific landmask file for the North American countries, like CONUS landmask file or Canada landmask file or Mexico landmask file? My CMAQ domain (below) includes parts of Canada… --- ## [PM25 composition and estimation of PM25 water (CMAQv5.3.1)](https://forum.cmascenter.org/t/pm25-composition-and-estimation-of-pm25-water-cmaqv5-3-1/2980)
**Author:** [@matthieupom](https://forum.cmascenter.org/u/matthieupom)\ **Replies:** 13\ **Last updated:** [April 24, 2024, 11:32am UTC](https://forum.cmascenter.org/t/pm25-composition-and-estimation-of-pm25-water-cmaqv5-3-1/2980 "2024-04-24T11:32:12Z")
Dear all, I use CMAQv5.3.1 and I have used the combine postprocessing script. Among the species I can find in the outputs, there are PM25\_TOT and some PM25 components (such PM25\_OC, PM25\_NO3 etc.). For information, I us… --- ## [Is it possible to integrate CMAQ output into ArcGis](https://forum.cmascenter.org/t/is-it-possible-to-integrate-cmaq-output-into-arcgis/4655)
**Author:** [@Svyatoslav](https://forum.cmascenter.org/u/Svyatoslav)\ **Replies:** 2\ **Last updated:** [January 25, 2024, 7:52am UTC](https://forum.cmascenter.org/t/is-it-possible-to-integrate-cmaq-output-into-arcgis/4655 "2024-01-25T07:52:01Z")
Good afternoon. Can you please tell me if CMAQ output can be integrated into ArcGIS to create a web application? --- ## [Sitecmp site file](https://forum.cmascenter.org/t/sitecmp-site-file/972)
**Author:** [@CMAQ\_user](https://forum.cmascenter.org/u/CMAQ_user)\ **Replies:** 18\ **Last updated:** [April 17, 2023, 5:00pm UTC](https://forum.cmascenter.org/t/sitecmp-site-file/972 "2023-04-17T17:00:54Z")
Hi, I was looking for the monitor locations csv file for the AQS and other networks too, but for AQS the given url in the codes seems not working. Can anyone suggest? Thanks. #\> This file can be downloaded from #\> htt… --- ## [Issues in output after running COMBINE post processing tool](https://forum.cmascenter.org/t/issues-in-output-after-running-combine-post-processing-tool/4055)
**Author:** [@munshimdrasel](https://forum.cmascenter.org/u/munshimdrasel)\ **Replies:** 12\ **Last updated:** [April 7, 2023, 2:18am UTC](https://forum.cmascenter.org/t/issues-in-output-after-running-combine-post-processing-tool/4055 "2023-04-07T02:18:53Z")
Hy, I have run CMAQv5.4 along with HDDM to calculate EGU sensitivity. I want to quantify: APOMI variable which has formula like this in specDef file (attached here): APOMI ,ug m-3 ,ALVPO1I\[1\] + ASVPO1I\[1\]… --- ## [Combine run issue](https://forum.cmascenter.org/t/combine-run-issue/450)
**Author:** [@epenning](https://forum.cmascenter.org/u/epenning)\ **Replies:** 30\ **Last updated:** [March 8, 2023, 4:47pm UTC](https://forum.cmascenter.org/t/combine-run-issue/450 "2023-03-08T16:47:36Z")
Hi all, I’m trying to run the combine post-processor and come across the following error: WARNING File does not exist:INFILE5 Value for GENSPEC: N returning FALSE Value for IOAPI\_CHECK\_HEADERS not defined;returning … --- ## [CMAQ5.3.1: how can we calculate the dust PM2.5 concentration?](https://forum.cmascenter.org/t/cmaq5-3-1-how-can-we-calculate-the-dust-pm2-5-concentration/3213)
**Author:** [@matthieupom](https://forum.cmascenter.org/u/matthieupom)\ **Replies:** 5\ **Last updated:** [March 7, 2023, 2:31am UTC](https://forum.cmascenter.org/t/cmaq5-3-1-how-can-we-calculate-the-dust-pm2-5-concentration/3213 "2023-03-07T02:31:39Z")
Hi, My question is a bit similar than the one posted in https://forum.cmascenter.org/t/questions-on-windblown-dust-and-pm10-calculation-by-cmaq/1750; but I do not find the useful information in the replies. Is it possi… --- ## [Eight hour average ozone](https://forum.cmascenter.org/t/eight-hour-average-ozone/734)
**Author:** [@yosuke](https://forum.cmascenter.org/u/yosuke)\ **Replies:** 12\ **Last updated:** [January 12, 2023, 6:03pm UTC](https://forum.cmascenter.org/t/eight-hour-average-ozone/734 "2023-01-12T18:03:24Z")
Hi, how would I calculate daily maximum 8 hour average ozone? I figured that CMAQ/TOOL/HR2DAY would be it. I tried to use File list format. It doesn’t seem to getting the end-time from the second file correctly and it… --- ## [Content of CMAQ netCDF files metadata](https://forum.cmascenter.org/t/content-of-cmaq-netcdf-files-metadata/3777)
**Author:** [@afernandez](https://forum.cmascenter.org/u/afernandez)\ **Replies:** 2\ **Last updated:** [December 15, 2022, 4:04am UTC](https://forum.cmascenter.org/t/content-of-cmaq-netcdf-files-metadata/3777 "2022-12-15T04:04:36Z")
Hello, I’m trying to dig a bit deeper into the output files (for cases with a Lambert projection) but something is not exactly clicking with me. I’m used to the WRF output files where the corner locations (in lat/lot) a… --- ## [How to calculate PM2.5 Si, Fe and Al?](https://forum.cmascenter.org/t/how-to-calculate-pm2-5-si-fe-and-al/3748)
**Author:** [@SiqiMa](https://forum.cmascenter.org/u/SiqiMa)\ **Replies:** 2\ **Last updated:** [November 30, 2022, 12:00am UTC](https://forum.cmascenter.org/t/how-to-calculate-pm2-5-si-fe-and-al/3748 "2022-11-30T00:00:01Z")
Hello all, I want to get the concentrations of some PM2.5 species like Si, Fe and Al. But they are not calculated in SpecDef\_cb6r3\_ae7\_aq.txt. I find ASIJ, AALJ and AFEJ in the CMAQ ACONC, so can I use ASIJ\*PM25AC to ge… --- ## [CMAQ combine module 1.3km](https://forum.cmascenter.org/t/cmaq-combine-module-1-3km/3374)
**Author:** [@kkkghs0828](https://forum.cmascenter.org/u/kkkghs0828)\ **Replies:** 12\ **Last updated:** [June 23, 2022, 8:08pm UTC](https://forum.cmascenter.org/t/cmaq-combine-module-1-3km/3374 "2022-06-23T20:08:09Z")
I tried to use combine module for 1.3km but it was not working with this error. Is there any solution? --- ## [An error occurred while doing species mixing](https://forum.cmascenter.org/t/an-error-occurred-while-doing-species-mixing/3278)
**Author:** [@bandaoshutiao](https://forum.cmascenter.org/u/bandaoshutiao)\ **Replies:** 5\ **Last updated:** [May 24, 2022, 1:14pm UTC](https://forum.cmascenter.org/t/an-error-occurred-while-doing-species-mixing/3278 "2022-05-24T13:14:34Z")
When the combine gets to this point, I get an error. The combine will still continue, but the final merged file has a large concentration of substances, such as the O3 concentration will reach 10 to the 30th power. If I … --- ## [Error in running COMBINE for CMAQ5.3.1](https://forum.cmascenter.org/t/error-in-running-combine-for-cmaq5-3-1/2165)
**Author:** [@nimish](https://forum.cmascenter.org/u/nimish)\ **Replies:** 15\ **Last updated:** [April 19, 2022, 5:47pm UTC](https://forum.cmascenter.org/t/error-in-running-combine-for-cmaq5-3-1/2165 "2022-04-19T17:47:39Z")
This is the error we get when we run COMBINE program to calculate parameters that require MET files from WRF runs. The program runs fine for parent domain but gives this error when run for nested domain. Surprisingly the… --- ## [How to use Combine tool to process VOC units into ppbV and μg/m3?](https://forum.cmascenter.org/t/how-to-use-combine-tool-to-process-voc-units-into-ppbv-and-g-m3/3144)
**Author:** [@ghb980003021](https://forum.cmascenter.org/u/ghb980003021)\ **Replies:** 5\ **Last updated:** [March 26, 2022, 6:06pm UTC](https://forum.cmascenter.org/t/how-to-use-combine-tool-to-process-voc-units-into-ppbv-and-g-m3/3144 "2022-03-26T18:06:32Z")
Hello everyone. I am doing CMAQ post-processing and found that the Combine tool can only process the units of VOC as ppbC, how can I process it as ppbV and μg/m3, can you provide the exact formula? Thank you for your a… --- ## [Only one hour of data in the results after running the COMBINE program](https://forum.cmascenter.org/t/only-one-hour-of-data-in-the-results-after-running-the-combine-program/3082)
**Author:** [@ghb980003021](https://forum.cmascenter.org/u/ghb980003021)\ **Replies:** 3\ **Last updated:** [March 15, 2022, 12:03pm UTC](https://forum.cmascenter.org/t/only-one-hour-of-data-in-the-results-after-running-the-combine-program/3082 "2022-03-15T12:03:29Z")
Hello everyone. When I use CMAQ’s ‘combine’ tool, the exported data is only for the first hour, and all the data after that are ‘NaN’ as shown in the picture. What is the reason for this? How can I fix it? I also found … --- ## [EQUATES grid coordinates](https://forum.cmascenter.org/t/equates-grid-coordinates/3018)
**Author:** [@MAlifa](https://forum.cmascenter.org/u/MAlifa)\ **Replies:** 3\ **Last updated:** [February 23, 2022, 2:12pm UTC](https://forum.cmascenter.org/t/equates-grid-coordinates/3018 "2022-02-23T14:12:01Z")
I am working with some yearly .nc files for daily average surface output at 12km resolution from the EQUATES project, but noticed these files have no explicit variables for longitude and latitude of the gridded data. Is… --- ## [Does 'COMBINE' tool have any limit on how many input files it can draw from?](https://forum.cmascenter.org/t/does-combine-tool-have-any-limit-on-how-many-input-files-it-can-draw-from/2702)
**Author:** [@skunwar](https://forum.cmascenter.org/u/skunwar)\ **Replies:** 1\ **Last updated:** [October 11, 2021, 7:36pm UTC](https://forum.cmascenter.org/t/does-combine-tool-have-any-limit-on-how-many-input-files-it-can-draw-from/2702 "2021-10-11T19:36:16Z")
I was wondering if there is a cap on how many different files we can receive input from (simultaneously at runtime) using the ‘COMBINE’ post-processing tool of CMAQ? --- ## [SIGILL error running Combine](https://forum.cmascenter.org/t/sigill-error-running-combine/2554)
**Author:** [@jsm2093](https://forum.cmascenter.org/u/jsm2093)\ **Replies:** 1\ **Last updated:** [August 4, 2021, 4:43pm UTC](https://forum.cmascenter.org/t/sigill-error-running-combine/2554 "2021-08-04T16:43:51Z")
I have compiled successfully Combine post processing tool. I’m trying to test the combine tool with my simulations and the benchmark case but I’m getting the following error. Someone knows what could be generating this e… --- ## [How to remove buffer cells from CAMx output file?](https://forum.cmascenter.org/t/how-to-remove-buffer-cells-from-camx-output-file/2426)
**Author:** [@Iqbal](https://forum.cmascenter.org/u/Iqbal)\ **Replies:** 0\ **Last updated:** [June 15, 2021, 7:29pm UTC](https://forum.cmascenter.org/t/how-to-remove-buffer-cells-from-camx-output-file/2426 "2021-06-15T19:29:23Z")
Hello, Let’s say I have a CAMx output file. The cell number of the file is 398 X 248 (with buffer cells). I want to delete buffer cells, i.e. make cell size number 396 X 246 from output files. Is there any way that ca… --- ## [CMAQ output sanity check](https://forum.cmascenter.org/t/cmaq-output-sanity-check/1724)
**Author:** [@skunwar](https://forum.cmascenter.org/u/skunwar)\ **Replies:** 16\ **Last updated:** [June 11, 2021, 3:07pm UTC](https://forum.cmascenter.org/t/cmaq-output-sanity-check/1724 "2021-06-11T15:07:33Z")
I just ran CMAQv5.3.2 for Jan 1 - March 1, 2014 using 2016 NEI emissions, and then used COMBINE and CALC\_TMETRIC postprocessing tools to get monthly average of PM25\_TOT and other PM25 components. I am getting very low av… --- ## [Model Baseline file is ill-formatted data in SMAT](https://forum.cmascenter.org/t/model-baseline-file-is-ill-formatted-data-in-smat/2287)
**Author:** [@Iqbal](https://forum.cmascenter.org/u/Iqbal)\ **Replies:** 1\ **Last updated:** [April 22, 2021, 9:48pm UTC](https://forum.cmascenter.org/t/model-baseline-file-is-ill-formatted-data-in-smat/2287 "2021-04-22T21:48:38Z")
Hello, I created SMAT .csv input files for the 2016 and 2028 using EPA2016v1 platform. I utilized ‘combine’ , ‘hr2day’, ’ nc2SMAT’ tools successfully. But when I tried to use the .csv files in the SMAT software, I am … --- ## [Make: \*\*\* \[combine.exe\] Error 2 undefined reference to \`nf\_get\_vara\_text\_](https://forum.cmascenter.org/t/make-combine-exe-error-2-undefined-reference-to-nf-get-vara-text/2122)
**Author:** [@Iqbal](https://forum.cmascenter.org/u/Iqbal)\ **Replies:** 6\ **Last updated:** [February 25, 2021, 7:57pm UTC](https://forum.cmascenter.org/t/make-combine-exe-error-2-undefined-reference-to-nf-get-vara-text/2122 "2021-02-25T19:57:37Z")
Hello @cjcoats @hogrefe.christian I am trying to build combine.exe from AMETV1.4 (I had successfully built it from AMET V1.2). Here is what I did (attached makefile Makefile\_combine.txt (2.4 KB) : I modified the libr… [Next page](https://forum.cmascenter.org/c/cmaq/post-processing/12.md?page=1)