Units Used in NO2, CO2, and SO2

[users212025]

What are the units used in the following data:
- NO2 from OMI/Aura NO2 Cloud-Screened Total and Tropospheric Column L3 Global Gridded 0.25 degree x 0.25 degree V3 (OMNO2d)
- CO from Aqua/AIRS L3 Daily Standard Physical Retrieval (AIRS-only) 1 degree x 1 degree V7.0 (AIRS3STD)
- SO2 from OMI/Aura Sulfur Dioxide (SO2) Total Column L3 1 day Best Pixel in 0.25 degree x 0.25 degree V3 (OMSO2e)

Are all three data in mol/cm2?

[GES DISC - jimacker]

Hello,

We are addressing your question with our staff Subject Matter Experts. Thank you for your patience.

[GES DISC - emilyz]

For the AIRS "CO_VMR" variable the variable is a unitless ratio. Please see the following User Guide for more information:
https://docserver.gesdisc.eosdis.nasa.gov/public/project/AIRS/V7_L3_User_Guide.pdf

For the OMNO2d_003 collection see the documentation tab on the landing page https://disc.gsfc.nasa.gov/datacollection/OMNO2d_003.html, specifically the README (https://acdisc.gesdisc.eosdis.nasa.gov/data/Aura_OMI_Level3/OMNO2d.003/doc/README.OMNO2.pdf) and the file specification (https://docserver.gesdisc.eosdis.nasa.gov/repository/Mission/OMI/3.3_ScienceDataProductDocumentation/3.3.2_ProductRequirements_Designs/OMNO2d_FileSpec_V003.pdf). Note the units for data fields is also specified in the Units data field attribute in each data file.

For the OMSO2e_003 collection see the documentation tab on the landing page (https://disc.gsfc.nasa.gov/datacollection/OMSO2e_003.html, specifically the README (https://acdisc.gesdisc.eosdis.nasa.gov/data/Aura_OMI_Level3/OMSO2e.003/doc/README.OMSO2e_2020-10-16.txt) and the file specification (https://docserver.gesdisc.eosdis.nasa.gov/public/project/OMI/OMSO2e_2020-11-25.fs). Again, the units for data fields is also specified in the Units data field attribute in each data file.