The last step in the analysis of the satellite measurements of tropospheric NO₂ is the conversion of the tropospheric slant columns SC_trop to tropospheric vertical columns VC_trop.

Fig 3.4.3.1: Conversion of the tropospheric slant columns SC_trop to tropospheric vertical columns VC_trop.

Image: AT2-ELS

This is achieved by application of a tropospheric airmass factor AMF_trop, which is derived from radiative transfer calculations that model the light path through the atmosphere. The following sections discuss some important influences on the tropospheric AMF:

• geometry (SZA and LOS),
• altitude,
• albedo, and
• wavelength.