# ISAM SA\_ACONC output error **URL:** \ **Category:** CMAQ-ISAM\ **Created:** [July 7, 2020, 6:45pm UTC](https://forum.cmascenter.org/t/isam-sa-aconc-output-error/1622 "2020-07-07T18:45:32Z")\ **Posts on this page:** 19\ **Page:** 1
**Author:** ![YukuiLi](https://avatars.discourse-cdn.com/v4/letter/y/6a8cbe/32.png) [@YukuiLi](https://forum.cmascenter.org/u/YukuiLi)\ **Post date:** [July 7, 2020, 6:45pm UTC](https://forum.cmascenter.org/t/isam-sa-aconc-output-error/1622/1 "2020-07-07T18:45:32Z")
Hello all, I am running CMAQ ISAM, to do source apportionment study. My CMAQ\_MASK file has 9 tags. The problem is the Initial Condition contributes exactly the same as all of my 9 source regions in the SA outputs. My isam\_control setting: TAG CLASSES |OZONE,NITRATE,VOC TAG NAME |GR1 REGION(S) |NA\_1 EMIS STREAM(S) |GRIDDED\_EMIS TAG NAME |GR2 REGION(S) |NA\_2 EMIS STREAM(S) |GRIDDED\_EMIS TAG NAME |GR3 REGION(S) |NA\_3 EMIS STREAM(S) |GRIDDED\_EMIS TAG NAME |GR4 REGION(S) |NA\_4 EMIS STREAM(S) |GRIDDED\_EMIS TAG NAME |GR5 REGION(S) |NA\_5 EMIS STREAM(S) |GRIDDED\_EMIS TAG NAME |GR6 REGION(S) |NA\_6 EMIS STREAM(S) |GRIDDED\_EMIS TAG NAME |GR7 REGION(S) |NA\_7 EMIS STREAM(S) |GRIDDED\_EMIS TAG NAME |GR8 REGION(S) |NA\_8 EMIS STREAM(S) |GRIDDED\_EMIS TAG NAME |GR9 REGION(S) |NA\_9 EMIS STREAM(S) |GRIDDED\_EMIS Thank you. ---
**Author:** ![qinch18](https://avatars.discourse-cdn.com/v4/letter/q/71e660/32.png) [@qinch18](https://forum.cmascenter.org/u/qinch18)\ **Post date:** [July 9, 2020, 2:49am UTC](https://forum.cmascenter.org/t/isam-sa-aconc-output-error/1622/2 "2020-07-09T02:49:07Z")
> [@YukuiLi](#): > > CMAQ hello, I want to know how to generate CMAQ\_MASK files. ---
**Author:** ![hogrefe.christian](https://avatars.discourse-cdn.com/v4/letter/h/74df32/32.png) [@hogrefe.christian](https://forum.cmascenter.org/u/hogrefe.christian)\ **Post date:** [July 9, 2020, 1:09pm UTC](https://forum.cmascenter.org/t/isam-sa-aconc-output-error/1622/3 "2020-07-09T13:09:38Z")
Hello Yukui, could you please provide some more details on the behavior you are observing? Which species are you looking at? How many days have you simulated, and does the relative magnitude of the IC tag vs. the source region tags change over time? Does the IC tag have the same magnitude as the sum of the region tags or are all tags (region tags and IC tag) identical? Does the behavior of the BC tag look reasonable? As noted in other forum posts discussing ISAM (e.g. [here](https://forum.cmascenter.org/t/what-is-difference-between-o3-othr-and-o3-gr1/1467) and [here](https://forum.cmascenter.org/t/how-to-run-cmaq-isam/1606/2)), we want to make sure you are aware of this [Known Issue with CMAQ-ISAMv5.3.1 predictions of secondary gas species](https://github.com/USEPA/CMAQ/issues/136). A bugfix release (v5.3.2) is expected soon that will address this issue. ---
**Author:** ![foley.kristen](https://avatars.discourse-cdn.com/v4/letter/f/d9b06d/32.png) [@foley.kristen](https://forum.cmascenter.org/u/foley.kristen)\ **Post date:** [July 9, 2020, 1:34pm UTC](https://forum.cmascenter.org/t/isam-sa-aconc-output-error/1622/4 "2020-07-09T13:34:30Z")
Here is a link with metadata on 2 example CMAQ mask files (US states and NOAA climate regions): [https://dataverse.unc.edu/dataset.xhtml?persistentId=doi:10.15139/S3/XDYYB9](https://dataverse.unc.edu/dataset.xhtml?persistentId=doi:10.15139/S3/XDYYB9) Here is a link to a README text file describing how these files were created: [https://drive.google.com/file/d/1bgbMyiFZMYP68zIm9iLFO36bwVY5fw\_o/view](https://drive.google.com/file/d/1bgbMyiFZMYP68zIm9iLFO36bwVY5fw_o/view) ---
**Author:** ![YukuiLi](https://avatars.discourse-cdn.com/v4/letter/y/6a8cbe/32.png) [@YukuiLi](https://forum.cmascenter.org/u/YukuiLi)\ **Post date:** [July 9, 2020, 4:27pm UTC](https://forum.cmascenter.org/t/isam-sa-aconc-output-error/1622/5 "2020-07-09T16:27:23Z")
Hello Hogrefe, I am looking at ozone source appointment. I have run half month dara. The IC tag do change over time. IC tag has the same magnitude as each region tag. So all region tags are identical and they are also the same as IC tag. The BC tag looks reasonable. Thanks. Christian Hogrefe via CMAS CENTER FORUM \<[cmas@discoursemail.com](mailto:cmas@discoursemail.com)\>于2020年7月9日 周四09:19写道： ---
**Author:** ![hogrefe.christian](https://avatars.discourse-cdn.com/v4/letter/h/74df32/32.png) [@hogrefe.christian](https://forum.cmascenter.org/u/hogrefe.christian)\ **Post date:** [July 9, 2020, 6:20pm UTC](https://forum.cmascenter.org/t/isam-sa-aconc-output-error/1622/6 "2020-07-09T18:20:21Z")
Hello Yukui, thanks for providing this additional information. To confirm, O3\_ICON = O3\_GR1 = O3\_GR2 = … O3\_GR9 in your SA\_ACONC and SA\_CONC output files across all grid cells and output time steps? If you created your own CMAQ\_MASK file, can you please post the header of that file and images showing the coverage of all 9 regions? Or are you using the NOAA climate region file posted on the CMAS data warehouse? Thanks, Christian ---
**Author:** ![YukuiLi](https://avatars.discourse-cdn.com/v4/letter/y/6a8cbe/32.png) [@YukuiLi](https://forum.cmascenter.org/u/YukuiLi)\ **Post date:** [July 9, 2020, 9:05pm UTC](https://forum.cmascenter.org/t/isam-sa-aconc-output-error/1622/7 "2020-07-09T21:05:49Z")
Thank you Christian. In my SA\_ACONC and SA\_CONC output files across all grid cells and output time steps, the data do shows O3\_ICON = O3\_GR1 = O3\_GR2 = … O3\_GR9. I create my own CMAQ\_MASK file. The header of my CMAQ\_MASK file is 🙂 file global attributes: IOAPI\_VERSION : ioapi-3.2: Id: init3.F90 120 2019-06-21 14:18:20Z coats EXEC\_ID : ??? ``` FTYPE : 1 CDATE : 2020119 CTIME : 531 WDATE : 2020119 WTIME : 531 SDATE : 0 STIME : 0 TSTEP : 0 NTHIK : 1 NCOLS : 396 NROWS : 246 NLAYS : 1 NVARS : 9 GDTYP : 2 P_ALP : 33 P_BET : 45 P_GAM : -97 XCENT : -97 YCENT : 40 XORIG : -2412000 YORIG : -1620000 XCELL : 12000 YCELL : 12000 VGTYP : 7 VGTOP : 5000 VGLVLS : ( 1, 0.9975 ) GDNAM : GRIDOUT_12US2_CR UPNAM : M3MERGE VAR-LIST : NA_1 NA_2 NA_3 NA_4 ``` NA\_5 NA\_6 NA\_7 NA\_8 NA\_9 ``` FILEDESC : US EPA COMMUNITY MULTISCALE AIR QUALITY MODEL METEOROLOGY-CHEMISTRY INTERFACE PROCESSOR HISTORY : ``` dimensions: TSTEP = 1 DATE-TIME = 2 LAY = 1 VAR = 9 ROW = 246 COL = 396 variables: integer TFLAG ( TSTEP, VAR, DATE-TIME ) units : \ long\_name : TFLAG var\_desc : Timestep-valid flags: (1) YYYYDDD or (2) HHMMSS ``` integer NA_1 ( TSTEP, LAY, ROW, COL ) long_name : NA_1 units : none var_desc : 1==mask region, 0==outside-mask region integer NA_2 ( TSTEP, LAY, ROW, COL ) long_name : NA_2 units : none var_desc : 1==mask region, 0==outside-mask region integer NA_3 ( TSTEP, LAY, ROW, COL ) long_name : NA_3 units : none var_desc : 1==mask region, 0==outside-mask region integer NA_4 ( TSTEP, LAY, ROW, COL ) long_name : NA_4 units : none var_desc : 1==mask region, 0==outside-mask region integer NA_5 ( TSTEP, LAY, ROW, COL ) long_name : NA_5 units : none var_desc : 1==mask region, 0==outside-mask region integer NA_6 ( TSTEP, LAY, ROW, COL ) long_name : NA_6 units : none var_desc : 1==mask region, 0==outside-mask region integer NA_7 ( TSTEP, LAY, ROW, COL ) long_name : NA_7 units : none var_desc : 1==mask region, 0==outside-mask region integer NA_8 ( TSTEP, LAY, ROW, COL ) long_name : NA_8 units : none var_desc : 1==mask region, 0==outside-mask region integer NA_9 ( TSTEP, LAY, ROW, COL ) long_name : NA_9 units : none var_desc : 1==mask region, 0==outside-mask region ``` There is only one grid cell in each of my region. ![image](https://canada1.discourse-cdn.com/flex027/uploads/cmas/original/1X/a6208ec84f08e476cbc22840d95b2003c3653243.png) ![image](https://canada1.discourse-cdn.com/flex027/uploads/cmas/original/1X/1ccd1ed340724e21a386bdecce96ff79cbb2308f.png) ![image](https://canada1.discourse-cdn.com/flex027/uploads/cmas/original/1X/f4875029d7681ad94e67f562f85c0a14a3cab48b.png) ![image](https://canada1.discourse-cdn.com/flex027/uploads/cmas/original/1X/a99b19c1e98f98f7711235e2d15c058443d86a5d.png) ---
**Author:** ![hogrefe.christian](https://avatars.discourse-cdn.com/v4/letter/h/74df32/32.png) [@hogrefe.christian](https://forum.cmascenter.org/u/hogrefe.christian)\ **Post date:** [July 9, 2020, 9:36pm UTC](https://forum.cmascenter.org/t/isam-sa-aconc-output-error/1622/8 "2020-07-09T21:36:21Z")
Hi Yukui, thanks for this additional information. While I don’t know if this causes your problem, the variables used to indicate the region masks should be of type real to represent fractions between 0 and 1, not integers. I don’t know how type conversions are handled when a variable is declared as real in CMAQ but defined as integer in the I/OAPI input file, but you might want to modify your CMAQ\_MASK file to store NA\_1, NA\_2, etc. as real values and try again. Similarly, I noticed that some of the file attributes in your file (e.g. P\_ALP, P\_BET etc.) appear to show integer rather than real values, assuming that what you posted is the output of ncdump. I don’t know if you used the I/O API Fortran library to generate the file, but if you did, that portion of the file header would typically look this: ``` :P_ALP = 33. ; :P_BET = 45. ; :P_GAM = -97. ; :XCENT = -97. ; :YCENT = 40. ; :XORIG = -2556000. ; :YORIG = -1728000. ; :XCELL = 12000. ; :YCELL = 12000. ; :VGTYP = -9999 ; :VGTOP = -9.e+36f ; :VGLVLS = 0.f, 0.f ; ``` Christian ---
**Author:** ![cjcoats](https://avatars.discourse-cdn.com/v4/letter/c/ac8455/32.png) [@cjcoats](https://forum.cmascenter.org/u/cjcoats)\ **Post date:** [July 9, 2020, 9:41pm UTC](https://forum.cmascenter.org/t/isam-sa-aconc-output-error/1622/9 "2020-07-09T21:41:50Z")
> I don’t know how type conversions are handled when a variable is declared as real in CMAQ but defined as integer in the I/OAPI input file **There are no conversions:** what you will get is bit-patterns 0 or 1, being interpreted as `REAL`s – which means either `REAL` zero or `REAL` denormal, respectively. ---
**Author:** ![YukuiLi](https://avatars.discourse-cdn.com/v4/letter/y/6a8cbe/32.png) [@YukuiLi](https://forum.cmascenter.org/u/YukuiLi)\ **Post date:** [July 11, 2020, 2:16pm UTC](https://forum.cmascenter.org/t/isam-sa-aconc-output-error/1622/10 "2020-07-11T14:16:45Z")
Thanks for the information Christian and cjcoats. I used ioapi m3mask to made my CMAQ\_MASK file. But according to m3mask, " Reads ASCII mask-data, specified by a file `MASKDATA` with lines containing either the columns and rows or the latitudes and longitudes, respectively, for the mask being specified, with one line per grid cell, and creates a GRIDDED output file `MASKFILE` , on the grid specified by `LLFILE` . `MASKFILE` contains one `INTEGER` variable `MASK` " The output of the m3mask variable is integer. And I don’t know how to convert the variable type of the file. Would you give me some suggestions? Thank you. ---
**Author:** ![hogrefe.christian](https://avatars.discourse-cdn.com/v4/letter/h/74df32/32.png) [@hogrefe.christian](https://forum.cmascenter.org/u/hogrefe.christian)\ **Post date:** [July 11, 2020, 3:48pm UTC](https://forum.cmascenter.org/t/isam-sa-aconc-output-error/1622/11 "2020-07-11T15:48:12Z")
Here is one thing you could try, but I’ll add two disclaimers: - I have not tried this myself - Generally, the safest way to manipulate I/O API files would be with the I/O API Fortran interface, i.e. read in the NA\_1, NA\_2, … NA\_9 variables with READ3 into integer arrays, copy them to real arrays, define a new file where the variables are M3REAL, and then write them out to this new file using WRITE3 1. Use ncdump to create a text file, i.e. `ncdump CMAQ_MASK >! CMAQ_MASK.cdl` 2. Use a text editor to open CMAQ\_MASK.cdl and edit the variable descriptions for NA\_1, NA\_2, etc. from integer to float, i.e. change “integer NA\_1” to “float NA\_1”, “integer NA\_2” to “float NA\_2”, etc. 3. Use ncgen with the edited text file to create a new CMAQ\_MASK file, i.e. `ncgen -o CMAQ_MASK_NEW CMAQ_MASK.cdl` where CMAQ\_MASK.cdl is the edited text file ---
**Author:** ![C.W.Huang](https://avatars.discourse-cdn.com/v4/letter/c/ecccb3/32.png) [@C.W.Huang](https://forum.cmascenter.org/u/C.W.Huang)\ **Post date:** [July 14, 2020, 6:58am UTC](https://forum.cmascenter.org/t/isam-sa-aconc-output-error/1622/12 "2020-07-14T06:58:17Z")
Hi Yukui, I had succcessfully run CMAQ\_ISAM with CMAQ\_MASK file. My ASCII file came from shpfile and transformed by ArcGIS.Then I used fortran with IOAPI interface to create the CMAQ\_MASK file as: > [@hogrefe.christian](#): > > Generally, the safest way to manipulate I/O API files would be with the I/O API Fortran interface, i.e. read in the NA\_1, NA\_2, … NA\_9 variables with READ3 into integer arrays, copy them to real arrays, define a new file where the variables are M3REAL, and then write them out to this new file using WRITE3 And here’s my variable descriptions: ![图片](https://canada1.discourse-cdn.com/flex027/uploads/cmas/original/1X/509f43e588ef64eabf3d73216d9d78721dfed13b.png) C.W.Huang ---
**Author:** ![YukuiLi](https://avatars.discourse-cdn.com/v4/letter/y/6a8cbe/32.png) [@YukuiLi](https://forum.cmascenter.org/u/YukuiLi)\ **Post date:** [July 28, 2020, 2:50pm UTC](https://forum.cmascenter.org/t/isam-sa-aconc-output-error/1622/13 "2020-07-28T14:50:06Z")
Thanks hogrefe.christian, cjcoats, C.W.Huang. I follow hogrefe.christian’s suggestion and recreate my CMAQ\_MASK file. The header of my CMAQ\_MASK file: filename: MASKFILE\_MERGE\_US\_NEW path: MASKFILE\_MERGE\_US\_NEW.nc file global attributes: IOAPI\_VERSION : ioapi-3.2: Id: init3.F90 120 2019-06-21 14:18:20Z coats EXEC\_ID : ??? ``` FTYPE : 1 CDATE : 2020119 CTIME : 531 WDATE : 2020119 WTIME : 531 SDATE : 0 STIME : 0 TSTEP : 0 NTHIK : 1 NCOLS : 396 NROWS : 246 NLAYS : 1 NVARS : 9 GDTYP : 2 P_ALP : 33 P_BET : 45 P_GAM : -97 XCENT : -97 YCENT : 40 XORIG : -2412000 YORIG : -1620000 XCELL : 12000 YCELL : 12000 VGTYP : 7 VGTOP : 5000 VGLVLS : ( 1, 0.9975 ) GDNAM : GRIDOUT_12US2_CR UPNAM : M3MERGE VAR-LIST : NA_1 NA_2 NA_3 NA_4 ``` NA\_5 NA\_6 NA\_7 NA\_8 NA\_9 ``` FILEDESC : US EPA COMMUNITY MULTISCALE AIR QUALITY MODEL METEOROLOGY-CHEMISTRY INTERFACE PROCESSOR ``` …skipping one line HISTORY : dimensions: TSTEP = 1 DATE-TIME = 2 LAY = 1 VAR = 9 ROW = 246 COL = 396 variables: integer TFLAG ( TSTEP, VAR, DATE-TIME ) units : \ long\_name : TFLAG var\_desc : Timestep-valid flags: (1) YYYYDDD or (2) HHMMSS ``` float NA_1 ( TSTEP, LAY, ROW, COL ) long_name : NA_1 units : none var_desc : 1==mask region, 0==outside-mask region float NA_2 ( TSTEP, LAY, ROW, COL ) long_name : NA_2 units : none var_desc : 1==mask region, 0==outside-mask region float NA_3 ( TSTEP, LAY, ROW, COL ) long_name : NA_3 units : none var_desc : 1==mask region, 0==outside-mask region float NA_4 ( TSTEP, LAY, ROW, COL ) long_name : NA_4 units : none var_desc : 1==mask region, 0==outside-mask region float NA_5 ( TSTEP, LAY, ROW, COL ) long_name : NA_5 units : none var_desc : 1==mask region, 0==outside-mask region ``` …skipping one line float NA\_6 ( TSTEP, LAY, ROW, COL ) long\_name : NA\_6 units : none var\_desc : 1==mask region, 0==outside-mask region ``` float NA_7 ( TSTEP, LAY, ROW, COL ) long_name : NA_7 units : none var_desc : 1==mask region, 0==outside-mask region float NA_8 ( TSTEP, LAY, ROW, COL ) long_name : NA_8 units : none var_desc : 1==mask region, 0==outside-mask region float NA_9 ( TSTEP, LAY, ROW, COL ) long_name : NA_9 units : none var_desc : 1==mask region, 0==outside-mask region ``` But it seems when it run for nearly one month. My CMAQ\_MASK file changed. I want to see the head of the MASK file. But seems I cannot. [yul18051@cn01 IWDW\_data]$ ncl Copyright © 1995-2014 - All Rights Reserved University Corporation for Atmospheric Research NCAR Command Language Version 6.2.1 The use of this software is governed by a License Agreement. See [http://www.ncl.ucar.edu/](http://www.ncl.ucar.edu/) for more details. ncl 0\> f = addfile(“MASKFILE\_MERGE\_US\_NEW.nc”,“r”) fatal:[“FileSupport.c”:3605]:\_NclFindFileExt: Requested file \ or \ does not exist. Would it change the CMAQ\_MASK file when running ISAM? I don’t get the result I expect, neither. My source apportionment result should be in high SA conc. near the source grid and low SA conc. away from the source grid. But it’s not. Would you help me to find out the problem? Would it be the reason the ISAM run may change my CMAQ\_MASK file or Would it be the reason my source region is only one grid cell and one grid cell is too small to do the source apportionment? Thank you. ---
**Author:** ![hogrefe.christian](https://avatars.discourse-cdn.com/v4/letter/h/74df32/32.png) [@hogrefe.christian](https://forum.cmascenter.org/u/hogrefe.christian)\ **Post date:** [July 28, 2020, 3:41pm UTC](https://forum.cmascenter.org/t/isam-sa-aconc-output-error/1622/14 "2020-07-28T15:41:21Z")
Hi Yukui, thank you for reporting back. I have a few comments and questions: - No, CMAQ ISAM should not, and in our experience does not, alter the CMAQ\_MASK file in any way since it is treated as input file. If something in the run script removed the file from the system after running for nearly a month, CMAQ ISAM should crash. If the file still exists on the system and CMAQ ISAM can find and use it, ncl should be able to open it, too. Can you view the file with ncdump, and if so, does the header look different from what you had created? - In your previous run, you reported that in “SA\_ACONC and SA\_CONC output files across all grid cells and output time steps, the data do shows O3\_ICON = O3\_GR1 = O3\_GR2 = … O3\_GR9”. For the new run, you report that “I don’t get the result I expect, neither. My source apportionment result should be in high SA conc. near the source grid and low SA conc. away from the source grid. But it’s not”. Could you provide more details on the patterns you are seeing in your new run? Is it still the same behavior as in your old runs, or something different? Are the different tags still identical or do they show at least some small differences? In general, defining a source region that’s a single grid cell should not be a problem, but the current code may have limitations that obscure the signal from such isolated emission sources. ---
**Author:** ![YukuiLi](https://avatars.discourse-cdn.com/v4/letter/y/6a8cbe/32.png) [@YukuiLi](https://forum.cmascenter.org/u/YukuiLi)\ **Post date:** [July 28, 2020, 4:13pm UTC](https://forum.cmascenter.org/t/isam-sa-aconc-output-error/1622/15 "2020-07-28T16:13:41Z")
Thank you Hogrefe.Christian. The result is not totally identical. But after running for one month, it seems very close or even identical again. At first, the result is much more reasonable even it’s still not like what I expect. My expectation is 1. ![image|549x500] (upload://tr3XD9ri6YyIFs5oa8i9IOkUsX1.png) 2. ![image](https://canada1.discourse-cdn.com/flex027/uploads/cmas/original/1X/b311c942a592ac66baf4d70aa68a147de5988d86.png) But my result is 3. ![image](https://canada1.discourse-cdn.com/flex027/uploads/cmas/original/1X/360d219c809a1d68c2a8dbd272f12e7c615b58d8.png) 4. ![image](https://canada1.discourse-cdn.com/flex027/uploads/cmas/original/1X/916316171daf2c86456b83ea1f6fd57bdba47c08.png) ---
**Author:** ![hogrefe.christian](https://avatars.discourse-cdn.com/v4/letter/h/74df32/32.png) [@hogrefe.christian](https://forum.cmascenter.org/u/hogrefe.christian)\ **Post date:** [July 28, 2020, 7:21pm UTC](https://forum.cmascenter.org/t/isam-sa-aconc-output-error/1622/16 "2020-07-28T19:21:16Z")
Thanks. Is the first image you posted based on some inert tracer result with a source in the grid cell you defined as ISAM region? To test whether the unexpected patterns happen because of limitations with the current ISAM code as it relates to secondary gas phase species or persisting problems with the CMAQ\_MASK file, you could re-do these simulations with changing the “tag class” from “OZONE” to “EC” in your isam\_control.txt file. For this primary species, the limitations of the current code should be less pronounced when applied to a very small source region such as yours. We do hope to release the updated CMAQ ISAM code within the next month or so, but unfortunately I cannot provide a definitive timeline at the moment. ---
**Author:** ![YukuiLi](https://avatars.discourse-cdn.com/v4/letter/y/6a8cbe/32.png) [@YukuiLi](https://forum.cmascenter.org/u/YukuiLi)\ **Post date:** [July 28, 2020, 7:35pm UTC](https://forum.cmascenter.org/t/isam-sa-aconc-output-error/1622/17 "2020-07-28T19:35:26Z")
Thank you Hogrefe.Christian. The expected is the CAMx OSAT run result I have with the same source apportionment run setting. I will try to do “tag class” as “EC”. Thanks. ---
**Author:** ![lihongli](https://avatars.discourse-cdn.com/v4/letter/l/f17d59/32.png) [@lihongli](https://forum.cmascenter.org/u/lihongli)\ **Post date:** [September 24, 2020, 3:41am UTC](https://forum.cmascenter.org/t/isam-sa-aconc-output-error/1622/18 "2020-09-24T03:41:03Z")
Hello YukuiLi, I recently learned how to make GRIDMASK files. I successfully generated the nc file with the M3MASK tool, but I am now very puzzled that the generated nc file has a variable in value, and the variable is the default MASK. What can I use How to change the variable name. There is only one variable in the script generated by running the script once, and there are many variables in your file. How is this generated?This is the header information of the nc file I generated ![image](https://canada1.discourse-cdn.com/flex027/uploads/cmas/original/1X/c781d1766cabb0fa06f25ce3af8f162d2d918d72.png) ---
**Author:** ![lizadams](https://avatars.discourse-cdn.com/v4/letter/l/49beb7/32.png) [@lizadams](https://forum.cmascenter.org/u/lizadams)\ **Post date:** [October 2, 2020, 7:59pm UTC](https://forum.cmascenter.org/t/isam-sa-aconc-output-error/1622/19 "2020-10-02T19:59:49Z")
@YukuiLi - It looks like you reposted this question, and it was answered on the following issue. [CMAQV5.3 ISAM Region not found](https://forum.cmascenter.org/t/cmaqv5-3-isam-region-not-found/1418/26)