Umkehr observations give useful information on the vertical distribution of ozone in the atmosphere.

A standard Umkehr observation consists of a series of C-pair wavelength measurements made on the clear zenith sky during morning or afternoon. The zenith sky must be free from clouds for a period of from one-half to one hour near sunrise or sunset to make Umkehr observations.

Standard Umkehr measurements involve the determination of values of NC, and preferably NA and ND, when SZA is 60, 65, 70, 74, 75, 77, 80, 83, 84, 85, 86.5, 88, 89, and 90 degrees. The normal Umkehr reduction is made using the information from the C wavelength pair, but Umkehr observations made using the A, C, and D wavelength pairs are useful as the knowledge of the radiative transfer process improves.

The example of Umkehr observations at Kyiv-Goloseyev site are given below.







This data would be processed by Windobson software to obtain ozone profile for that day.