How to run WRF-chem with dust option to have aerosol optical depth output?

[Setareh Rahimi]

Dear WRF-chem users,

I am very new in WRF-chem and would like to run the model to simulate dust. I just followed exactly the steps and name list that have been mentioned in the following link:

https://ruc.noaa.gov/wrf/wrf-chem/tutorialexercises/tutorialexercises001.html

I could run the model successfully (the model version is: 4.4). However, I need to have aerosol optical depth output. I did not get any output for aerosol optical depth following the structures provided in the aforementioned link so I set:

 

aer_op_opt                          = 1,

opt_pars_out                        = 1,

But again did not get any output for aerosol optical depth.

Would you please kindly advise me in terms of this issue?

Any suggestions would be appreciated.

Many thanks in advance,

Best wishes,

[Rajesh Kumar]

Hi there,

With these namelist options, you should have EXTCOEF55 variable in the output that represents the exticntion coefficient at 550 nm in the units of km^-1. You need to calculate layer thickness (can be done by using PH and PHB variables from the WRF-Chem output). The final step is to calculate AOD as multiplication of EXTCOEF55 with the layer thickness (make sure you have it in km). 

Alternatively, you can add "tauaer1, tauaer2, tauaer3, and tauaer4" to the model output using runtime I/O option. They represent layer AOD at 300, 400, 600, and 999 nm. The vertical integral of these quantities will give you total AOD at these wavelengths and then you can use the Angstrom power law to derive AOD at any wavelength. 

Hope this helps,

Rajesh

--

Rajesh Kumar, Project Scientist III

Research Applications Laboratory 

National Center for Atmospheric Research 

E-mail: rku...@ucar.edu

Phone: +1-303-497-1413

Web: https://staff.ucar.edu/users/rkumar

[Rama Krishna Karumuri]

Hi Setareh,

you need to switch on the variables Tauaer1, Tauaer2, Tauaer3, and Tauaer4, which are available in the registry.chem in the registry folder.

and then run the WRF-Chem you will get the AOD values, Tauaer variable nothing but AOD values.

Also, find the following PPT on the 4th page

https://ruc.noaa.gov/wrf/wrf-chem/wrf_tutorial_2011/Aerosol_Interactions_WRFCHEM.pdf

the Tauaer3 variable is at 500nm which is approximate to the MODIS 550 AOD variable. 

Best Regards,

Rama Krishna Karumuri. 

--
To unsubscribe from this group and stop receiving emails from it, send an email to wrf-chem+u...@ucar.edu.

--

Rama Krishna Karumuri

[Indranil Nandi]

Dear Rahimi,

Anyhow you will not be able to get aerosol optical depth as a direct output variable in any of WRF_Chem simulations. You have to calculate AOD from the output variable 'EXTCOF55' (Extinction coefficients for .55um). 

 ########################################### Calculation Using MATLAB ####################################################

Height_in_Km = ((PH + PHB)/(9.81))*(1000) ##### This will calculate the height between WRF levels in Km where PH = Perturbation Geopotential and PHB = Base-State Geopotential.

Then if you have number of levels in your output is suppose K

for X=1:K
    Distance_Between_Levels (:,:,X) = Height_in_Km(:,:,X+1) - Height_in_Km(:,:,X);
    EXTCOF55_Converted(:,:,X) = (EXTCOF55(:,:,X).*Distance_Between_Levels(:,:,X));
end

AOD(:,:)= nansum(EXTCOF55_Converted,3);  ############## Mean of the Level Dimension #########

#################################################### END ##############################################################

To calculate AOD, you just need to integrate the extinction coefficient throughout the entire model column; i.e. multiple the extinction coefficient by the thickness of the model box and sum all the boxes:
AOD = ∑ EXT(l) * dz(l)

 

In the user groups you will be able to find the details of this calculation.

--

To unsubscribe from this group and stop receiving emails from it, send an email to wrf-chem+u...@ucar.edu.

--

Indranil Nandi

[Setareh Rahimi]

Dear Rama,

As you suggested, I run the model to get variables Tauaer1, Tauaer2, Tauaer3, and Tauaer4.

However, once I try to plot them, they had no data values. I wonder why this happened. Would you please advise me in this regard?

Many thanks in advance,

[Rama Krishna Karumuri]

Dear Setareh,

Did you check the data in a single level or for all levels, if you check for a single level, please integrate the data for all levels and then check the output?  

Also please check your WPS folder GEOGRID.TBL file, make sure it should be linked with  GEOGRID.TBL.ARW_CHEM file. 

Thank you.  

--

Rama Krishna Karumuri

[Setareh Rahimi]

Dear Rama,

I check the data for all levels and there were no values. Regarding WPS I already linked GEOGRID.TBL.ARW_CHEM.

Really have no ideas!!

[sherin hassan bran]

Hi Rahimi,

                 Could you make sure you turn on "aer_ra_feedback=1" in your namelist.input, if yes providing your namelist here might be helpful to overlook.

With Best Regards

Sherin Hassan Bran
Research Assistant (PhD Scholar)
Atmospheric Research Unit
National Astronomical Research Institute of Thailand
Chiang Mai, Thailand

Mob:0903212373

[Rama Krishna Karumuri]

Dear Setareh,

I got it, you using option 401 (Dust concentration only), which will not provide TAUAER values.

 Use option 300 or 301 and switch off all chemical parameters just like your present namelist, it will provide you with the TAUAER values with only dust concentrations.

Thank you. 

On Thu, Aug 11, 2022 at 2:37 PM Setareh Rahimi <setareh...@gmail.com> wrote:

Dear Rama,

Sure, please check the attached file.

Best wishes,

On Thu, Aug 11, 2022 at 3:48 PM Rama Krishna Karumuri <k.b....@gmail.com> wrote:

Dear Setareh,

Can you please share your namelist to check 

thank you. 

--

S.Rahimi

--

Rama Krishna Karumuri