# Run PXLSM WRF for CMAQ V5.5

**URL:** <https://forum.cmascenter.org/t/run-pxlsm-wrf-for-cmaq-v5-5/5836>\
**Category:** CMAQ\
**Created:** [June 3, 2025, 4:54am UTC](https://forum.cmascenter.org/t/run-pxlsm-wrf-for-cmaq-v5-5/5836 "2025-06-03T04:54:49Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![brucelee](https://avatars.discourse-cdn.com/v4/letter/b/3da27b/32.png) [@brucelee](https://forum.cmascenter.org/u/brucelee)\
**Post date:** [June 3, 2025, 4:54am UTC](https://forum.cmascenter.org/t/run-pxlsm-wrf-for-cmaq-v5-5/5836/1 "2025-06-03T04:54:50Z")

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Hi~ everyone~

I am currently using WRF\_V4.7.0 with PX LSM and OBSGRID enabled, in preparation for coupling with CMAQ\_V5.5. We have followed the recommended namelist settings from the following link:

> **[PX-ACM-WRFV4.6-MPAS.pdf](https://github.com/USEPA/CMAQ/blob/main/DOCS/Users_Guide/PDF/PX-ACM-WRFV4.6-MPAS.pdf)**

However, we are encountering a runtime issue when running WRF. The rsl.error.0000 file shows the following fatal error:

## PX LSM will use the MODIS landuse tables OBS NUDGING is requested on a total of 1 domain(s). -------------- FATAL CALLED --------------- FATAL CALLED FROM FILE: LINE: 415 RIBX never exceeds RIC, RIB(i,kte) = 0.000000 THETAV(i,1) = NaN MOL= NaN TCONV = 0.000000 WST = NaN KMIX = 45 UST = NaN TST = NaN U,V = NaN NaN I,J= 1 199

I would like to understand the cause of this error. If anyone has experience with this issue or insights into its potential causes, I would greatly appreciate your suggestions. Thank you!

Here are our namelistinputs:  
[namelist.oa\_201904.txt](https://forum.cmascenter.org/uploads/short-url/gGRSJU5gDJJI08LeC2SsTL0XwTj.txt) (2.5 KB)  
[namelist.wps.201904\_ERA5.txt](https://forum.cmascenter.org/uploads/short-url/5WLZKy2NigQFng1PWFQOdKXSm2k.txt) (2.0 KB)  
[namelist\_original.input.201904\_PXLSM.txt](https://forum.cmascenter.org/uploads/short-url/iFkATB9JacFYK0EQ8n1T4c5HzSa.txt) (9.4 KB)

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**Author:** ![pleim.jon](https://avatars.discourse-cdn.com/v4/letter/p/4bbf92/32.png) [@pleim.jon](https://forum.cmascenter.org/u/pleim.jon)\
**Post date:** [June 3, 2025, 1:50pm UTC](https://forum.cmascenter.org/t/run-pxlsm-wrf-for-cmaq-v5-5/5836/2 "2025-06-03T13:50:42Z")

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This error in acm pbl code tends to catch problems that can be occurring anywhere in the model. It says that thetav, U, and V are all NaN. Something big is wrong. I can’t tell what it is.

I noticed that you timestep is very small for a mother domain of 81 km

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**Author:** ![brucelee](https://avatars.discourse-cdn.com/v4/letter/b/3da27b/32.png) [@brucelee](https://forum.cmascenter.org/u/brucelee)\
**Post date:** [June 5, 2025, 3:40am UTC](https://forum.cmascenter.org/t/run-pxlsm-wrf-for-cmaq-v5-5/5836/3 "2025-06-05T03:40:56Z")

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Thank you for your reply. I will double-check to see if there is any issue with the OBSGRID observation data or the processing steps.

Initially, I used a time step of 120, but I encountered the same problem. Later, I tried using smaller time steps to test and see if it would help.

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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 30, 2025, 4:02pm UTC](https://forum.cmascenter.org/t/run-pxlsm-wrf-for-cmaq-v5-5/5836/4 "2025-06-30T16:02:28Z")

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