CMAQ_v5.5 PM concentration extremely high when turning on inline windblown dust option

CMAQ
1

Hi everyone, I’m using CMAQv5.5 to run simulations for California. I was using PX LSM scheme for WRFv4.6.1 and turned on inline windblown dust option. No errors showed up but the result of PM2.5, PM10 are extremely high (PM2.5 up to 300 µg/m³, PM10 up to 1600 µg/m³) in some desert areas, where the LAI is very low. However when I turned off windblown dust option, the concentration is quite realistic. (see screenshots attached)

Screenshot 2025-08-11 at 11.33.22 AM
Screenshot 2025-08-11 at 11.33.22 AM1012×466 159 KB

Screenshot 2025-08-11 at 11.34.29 AM
Screenshot 2025-08-11 at 11.34.29 AM522×473 324 KB

I believe for CMAQv5.5, the windblown dust option only uses inputs from MCIP/WRF, so I’m wondering if I have any settings wrong for WRF and CCTM scripts. I have attached my loaded modules, WPS and WRF inputs, and CCTM scripts. Any suggestions and advice would be truly helpful to me. Thank you!

Currently Loaded Modules:
  1) gcc/13.3.0        6) netcdf-c/4.9.2          11) hdf5/1.14.3
  2) python/3.11.9     7) netcdf-fortran/4.6.1    12) flex/2.6.4
  3) openblas/0.3.28   8) parallel-netcdf/1.12.3  13) bison/3.8.2
  4) openmpi/5.0.5     9) zlib/1.3.1              14) nano/8.0
  5) usc/13.3.0       10) libpng/1.6.39           15) time/1.9

run_cctm_CA_2019_01_multiday.csh (38.7 KB)

namelist.wps.txt (766 Bytes)

namelist.input.txt (4.2 KB)

2

An issue with the inline dust module was identified last fall: Error in NLCD40 Land Use Mapping for Inline Windblown Dust Calculations · Issue #220 · USEPA/CMAQ · GitHub

We recommend switching to 5.5.0.1 or later to take advantage of a bugfix that was added to the ‘5.5+’ branch last December that can decrease WBD emissions by a factor of 3-4.

Here is information on the 5.5 bugfix releases:

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3

Kristen’s suggested bugfix will bring down the erroneous windblown dust emissions significantly in your case. Be advised that dust is still likely to be biased high, though. Further windblown dust reduction options will be available with the next CMAQ version that will be released for use soon.

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