Figure 1.

In the Input block we list the monthly mean solar irradiances (MSI), the radiances (wavelength, line‐of‐sight (row) and position (along‐orbit) dependent), the laboratory cross sections of NO₂, H₂O, and CHOCHO (X sections), the atmospheric (RS air) and liquid water (RS water) ring spectra convolved with the OMI slit function, the cloud fraction (CF) estimates provided by an independent retrieval from OMI observations. The preliminary estimates of the NO₂, H₂O and CHOCHO slant column densities (SCD‐1), as well as the spectral fixed‐pattern corrections (FPC) are used as additional input during the second‐pass SCD retrieval. RS denotes the amplitudes of the combined air and water ring spectrum.