WRF-Chem PM2.5 Anomaly: EDGAR+MEGAN > EDGAR+MEGAN+FINN?

[Nafisa Islam]

Hi all,

I am running two WRF-Chem (version 3.9) simulations with a time period from 1 to 10 January, 2020. My first simulation runs with anthropogenic emission from EDGARv5, biogenic emission from MEGANv2.1, and fire emission from FINNv1.5. My second simulation runs with the same anthropogenic and biogenic emissions but no fire emission from FINN. I have processed the hourly wrfchemi files using anthro_emiss, the wrfbiochemi files using megan_bio_emis and the wrffirechemi files using fire_emis utility. All the files in both the simulations are same and the only difference is second simulation contains fire emissions. I am using the RACM-SOA-VBS aerosol mechanism (chem_opt=3). The full time period (1-10 January, 2020) simulations were run within one go, with no restart in between for both the simulations.

However, after running the WRF-Chem simulations when I compare the daily mean of each wrfout files for each day, the EDGAR+MEGAN simulation PM2.5 concentration is coming out to be greater than the EDGAR+MEGAN+FINN simulation PM2.5 concentration in some locations! (pic attached) Can anyone please tell me why this is happening? Theoretically EDGAR + MEGAN + FINN concentration should be greater than EDGAR + MEGAN concentration in all places within the domain. 

I am attaching my namelist.input for both the simulations. 

Any help would be greatly appreciated.

Regards,

Nafisa

[Gabriele Pfister]

Hello Nafisa

please be aware that we cannot help you when you are using chemistry schemes other than the by us developed suite of MOZART chemical mechanisms. 

However, one thing I noticed in your namelist is that you enable the feedbacks between chemistry and meteorology.  This means that your meteorology will not be identical between the runs and this could maybe explain some of what you see. If you want to keep the meteorology identical between the two runs you have to turn off feedbacks. 

Gabi

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Gabriele Pfister

Atmospheric Chemistry Observations & Modeling (ACOM) Lab

NSF National Center for Atmospheric Research (NCAR)

Email: pfi...@ucar.edu

Work Phone: +1 303 497 2915

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