Articles | Volume 10, issue 12
Research article
20 Dec 2017
Research article |  | 20 Dec 2017

Retrieving vertical ozone profiles from measurements of global spectral irradiance

Germar Bernhard, Irina Petropavlovskikh, and Bernhard Mayer

Abstract. A new method is presented to determine vertical ozone profiles from measurements of spectral global (direct Sun plus upper hemisphere) irradiance in the ultraviolet. The method is similar to the widely used Umkehr technique, which inverts measurements of zenith sky radiance. The procedure was applied to measurements of a high-resolution spectroradiometer installed near the centre of the Greenland ice sheet. Retrieved profiles were validated with balloon-sonde observations and ozone profiles from the space-borne Microwave Limb Sounder (MLS). Depending on altitude, the bias between retrieval results presented in this paper and MLS observations ranges between −5 and +3 %. The magnitude of this bias is comparable, if not smaller, to values reported in the literature for the standard Dobson Umkehr method. Total ozone columns (TOCs) calculated from the retrieved profiles agree to within 0.7±2.0 % (±1σ) with TOCs measured by the Ozone Monitoring Instrument on board the Aura satellite. The new method is called the Global-Umkehr method.

Short summary
The vertical distribution of atmospheric ozone has historically been measured from the ground by analysing the wavelength dependence of zenith radiation. Our method retrieves the same information from global irradiance, which is defined as radiant flux received from the entire upper hemisphere, including the Sun. The new method makes existing long-term data sets of global irradiance available for studying ozone profiles. The accuracy of the new method is similar to that of the legacy method.