Guidance Required on Tropospheric NO₂ Column Calculation from WRF-Chem

[Deepak]

Hi everyone,

I am working with WRF-Chem output and trying to calculate the tropospheric NO₂ column density over India. I would really appreciate some guidance on the correct methodology.

Specifically, I would like to confirm:

1. The correct approach to convert NO₂ mixing ratio (ppmv/ppbv) into number density

2. Proper method for vertical integration (using pressure, temperature, and layer thickness)

3. Best way to define the tropopause (lapse rate vs fixed pressure like 100–200 hPa)

4. Any recommended practices for making the results comparable with satellite data (like OMI – AMF or averaging kernel)

If anyone has experience, sample codes, or relevant papers, please share.

Thanks in advance!