# NaN or Infinity detected on processor

**URL:** <https://forum.cmascenter.org/t/nan-or-infinity-detected-on-processor/6226>\
**Category:** MPAS-CMAQ\
**Created:** [June 8, 2026, 4:41am UTC](https://forum.cmascenter.org/t/nan-or-infinity-detected-on-processor/6226 "2026-06-08T04:41:52Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![wxy](https://avatars.discourse-cdn.com/v4/letter/w/eada6e/32.png) [@wxy](https://forum.cmascenter.org/u/wxy)\
**Post date:** [June 8, 2026, 4:41am UTC](https://forum.cmascenter.org/t/nan-or-infinity-detected-on-processor/6226/1 "2026-06-08T04:41:52Z")

</div>

Hello, everyone.

I am running the model using the officially released MPAS-CMAQ. All input files are from the official release, and I have not made any modifications. When I run the simulation starting from January 1, 2017, using the default script (config\_px\_modis\_veg=0), MPAS-CMAQ runs normally. However, when I set config\_px\_modis\_veg=1 (because I want to use MODIS as input), the model always crashes at the same point. The error message reads:

NaN or Infinity detected on processor 022  
During VDIFF : Gas NaN | Aer NaN | Non 4.831E-05.

At first, I thought this was due to issues with the “lai12m” or “greenfrac” included with MPAS-CMAQ, so I created my own versions of “lai12m” and “greenfrac”. Strangely, MPAS-CMAQ still crashes, but at a different time than before. It should be noted that when I run the simulation starting from 2017-07-01, this problem does not occur, and the model runs normally. I would like to know why the above error occurs and whether `config_px_modis_veg=1` is a deprecated option. I would be very grateful for any reply.

[run.csh](https://forum.cmascenter.org/uploads/short-url/8OsdbB9MgyoHGqdWs96DaTramEk.csh) (25.8 KB)

I have uploaded my run script and the specific error messages are as follows:

```auto
 Processing Day/Time [YYYYDDD:HHMMSS]: 2017006:233000
   Which is Equivalent to (UTC): 23:30:00 Friday, Jan. 6, 2017
   Time-Step Length (HHMMSS): 000730
        NEW_START | F
        NEW_START | F
        NEW_START | F
        NEW_START | F
        NEW_START | F
        NEW_START | F
        NEW_START | F
        NEW_START | F
        NEW_START | F
        NEW_START | F
        NEW_START | F
        NEW_START | F
        NEW_START | F
        NEW_START | F
        NEW_START | F
        NEW_START | F
        NEW_START | F
        NEW_START | F
   NaN or Infinity detected on processor 022
   During VDIFF : Gas NaN | Aer NaN | Non 4.831E-05
   NaN or Infinity detected on processor 019
   During VDIFF : Gas NaN | Aer NaN | Non 3.163E-05
   NaN or Infinity detected on processor 023
   During VDIFF : Gas NaN | Aer NaN | Non 2.065E-05
===================================================================================

= BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES= RANK 0 PID 4996 RUNNING AT ls-Super-Server= KILLED BY SIGNAL: 9 (Killed)

===============================================

```

WXY

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<div class="post-metadata">

**Author:** ![wong.david-c](https://avatars.discourse-cdn.com/v4/letter/w/bcef8e/32.png) [@wong.david-c](https://forum.cmascenter.org/u/wong.david-c)\
**Post date:** [June 24, 2026, 2:36pm UTC](https://forum.cmascenter.org/t/nan-or-infinity-detected-on-processor/6226/2 "2026-06-24T14:36:27Z")

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Hi WXY,

I have used the released code, input and set config\_px\_modis\_veg = 1, but I was not able to reproduce the crash you have reported (the code still able to finish to completion). The results with setting config\_px\_modis\_veg = 0 and = 1 are different. Do you have any additional information? Please feel free to contact me directly ([wong.david-c@epa.gov](mailto:wong.david-c@epa.gov)). Thanks. Cheers, David