Atmospheric Toolbox

Convert the unit from molecules/m^2 to ppm


Currently, I am working on Sentinel 5p data in molecules/cm2. But I need to convert it to ppm (parts per million) in order to compare it with standard units in ppm or microgram/m^3.
I know the data here is column density and [ppm] is the number of compounds molecules divided by the number of air molecules (weighted), and in order to convert molecules/m^2 to ppm we need to divide it by the column length (length or height of the atmosphere which contains the NO2). Then one can convert to ppm, but the problem here is the concentration will be an average on all the column length (not on a specific region).

I would be very grateful if anyone can give me some suggestions.


This is an inherent limitation of the way the satellite can measure the atmosphere. You won’t be able to retrieve parts of a vertical column. See also this earlier comment.
The way the S5P NO2 L2 product is able to split a total column in a tropospheric and stratospheric column is already quite an achievement (and requires the use of an atmospheric model to achieve it).

Thanks for this information. Maybe it will be easiest to do the opposite. I mean if the user will be converted from ppm to mol\m^2.