Output AOD all zeros

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Joined: Thu Dec 24, 2020 1:58 am

Output AOD all zeros

Post by woodllan » Thu Dec 24, 2020 2:06 am

Dear colleagues,

I am running WRF-chem with the aerosol settings of aer_opt = 1 and aer_op_opt = 2.
However, all the output variables related to AOD contain all zeros.

Would you please give me a hint about what could go wrong?
Here is my namelist:
(5.58 KiB) Downloaded 23 times

Thank you very much & Happy Holidays!

Posts: 7
Joined: Thu Dec 24, 2020 1:58 am

Re: Output AOD all zeros

Post by woodllan » Fri Jan 08, 2021 11:25 pm

Consulted Dr. Jordan Schnell from CIRES.

AOD contains all zeros because in "WRF v4.2, AOD_OUT and AOD2D_OUT are not actually hooked up correctly - they are only initialized in phys/module_radiation driver.F."

Instead, we can output the extinction coefficient as follows:

"Set opt_pars_out = 1 in the chem namelist. That should then output 3D extinction coefficients at 3 different wavelengths (300, 550, and 1060 nm), which you can integrate vertically to get AOD. Take a look at Registry/registry.chem, this line tells you what variables are activated (and memory allocated for) with the opt_pars_out namelist option:

package opt_out opt_pars_out==1 - ext_coef:extcof3,extcof55,extcof106,extcof3_5,extcof8_12;bscat_coef:bscof3,bscof55,bscof106;asym_par:asympar3,asympar55,asympar106

i.e., also scattering coefficients and asymmetry parameters

Then you will also probably need to either change the Registry (and then ./clean -a, recompile) or add an iofields file to your run directory (and namelist) to add the variable(s) you want to the history channel. For example, the extinction coefficient at 550 nm should be output because it has an “h” (history):

state real extcof55 ikjf ext_coef 1 Z h "EXTCOF55" "Extinction coefficients for .55um" "km^-1”


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Joined: Fri Jul 10, 2020 11:11 pm

Re: Output AOD all zeros

Post by linlu9876 » Tue Feb 02, 2021 9:01 am

Dear woodllan ,

Acc to your answer, how to now calculate the AOD from the ext coefficient variables?

Please help.


Posts: 141
Joined: Thu Feb 27, 2020 10:58 pm

Re: Output AOD all zeros

Post by jordanschnell » Tue Feb 02, 2021 4:42 pm

Hi Lin,

To calculate AOD, you just need to integrate the extinction coef throughout the entire model column; i.e. multiple the extinction coef by the thickness of the model box and sum all the boxes:

AOD = ∑ EXT(l) * dz(l)

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