Running WRF-Chem with only aerosol direct effect - subgrid convective trransport

[Rui Pedro Silva]

Dear all,

I have a question related to running WRF-Chem model with aerosol direct effects.

The WRF-Chem User's Guide says that for running the model with only direct effects (aer_ra_feedback=1) the options progn, wetscav_onoff and cldchem_onoff should be turned off. This is because we don't want aerosols interacting with clouds. However, there are other cloud related namelist variables that I am not sure if I should turn off as well, namely, chem_conv_tr, conv_tr_wetscav, and conv_tr_aqchem.

Following the logic of the Users' Guide, at least conv_tr_wetscav and conv_tr_aqchem should be turned off, but I am not sure about chem_conv_tr.

Does anyone know what to do with these variables when running with only aerosol direct effects?

P.S.: I'm using chem_opt = 8

Thank you.

Kind regards,
Rui Silva

[Mary Barth]

Rui Silva,

I think it is wise to allow convective transport, convective wet deposition, and dry & wet deposition affect aerosol concentrations. So, do turn on chem_conv_tr, conv_tr_wetscav, etc. 

For conv_tr_aqchem, it will also produce a better representation of sulfate formation. Yet, you could try your simulation with it off as well. You may want to do a couple test simulations to see if there is a difference -- for sulfate concentrations, and for how long the model takes to run. 

- Mary

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Mary Barth 

Senior Scientist   

phone: 303-497-8186    email: bar...@ucar.edu

NSF - National Center for Atmospheric Research

P.O. Box 3000

Boulder, CO 80307

Staff web page

SIMA Web Site

MUSICA Web Site

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[Rui Pedro Silva]

Dear Dr. Mary,

Thank you for the response and advise.

I am doing a couple of test simulations to see the impact of this options in the modeled results.

Kind regards,

Rui Silva