WRF v4.5.1 auxinput15 external AOD always read as zero (aer_opt=2)

[Yue Meng]

Hello,

I am using WRF-ARW v4.5.1 (non-WRF-Chem) with RRTMG radiation and trying to prescribe external aerosol optical depth (AOD) via auxinput15:
aer_opt = 2
aer_aod550_opt = 2
aer_angexp_opt = 3,
aer_ssa_opt = 3,
aer_asy_opt = 3,
aer_type = 1,
ra_sw_physics = 4
ra_lw_physics = 4

Auxinput settings:
io_form_auxinput15 = 2
auxinput15_inname = "wrfaerinp_d<domain>_<date>"
auxinput15_interval = 60
frames_per_auxinput15 = 1

The auxinput15 files (e.g. wrfaerinp_d01_YYYY-MM-DD_HH:00:00) contain non-zero AOD5502D / TAOD5502D, with correct grid size and valid Times. This is verified by ncdump and Python.

At runtime, WRF opens the files successfully, but always reports:
aer_aod550_opt=2: AOD@550 nm read from auxinput (min= 0.000 max= 0.000)
As a result, SWDOWN and T2 are bitwise identical between baseline and strongly perturbed AOD experiments.

Question:

• Is external AOD via auxinput15 actually supported in standard WRF-ARW, or is this functionality only intended to work fully in WRF-Chem?
• Are additional variables required in auxinput15 beyond AOD5502D / TAOD5502D?

Thanks in advance for any clarification.

 

[kwerner]

Hi, This option should work with standard WRF-ARW. Do you mind attaching your full namelist.input file, as well as your error/out log(s)? If you have multiple rsl.* files, package them into a single .tar or zipped file and attach here. Thanks!

 

[Yue Meng]

Thanks for the reply!

I will attach:

• the full namelist.input,
• the rsl.out.* and rsl.error.* logs,
• and one example wrfaerinp_d01_2015-05-21_01:00:00 file.

I hope this helps identify whether there is any issue with the auxinput15 format or metadata. I am including the wrfaerinp file because WRF reports that it successfully opens the auxinput15 stream, but the logged AOD values are always zero, even though the file itself contains non-zero AOD.

I also found a previous WRF forum post (see here) describing exactly the same behavior (the auxinput15 file is opened, but the AOD is read as zero). The issue in that post was eventually resolved, but the solution was not described.