Impact of the ozone profile on the surface UV radiation: Analyses of the Umkehr and UV measurements at Belsk (52°N, 21°E), Poland

Abstract

We consider changes of the ozone vertical profile using Umkehr observations taken at Belsk (52°N, 21°E) by means of the Dobson spectrophotometer in the period 1963–1998. The ratio of ozone content in the Umkehr layers 1–4 (0–23.5 km) to total column ozone (layers 1–10) is used as a proxy characterizing the shape of the ozone profile. The long‐term tendency in the ratio appears statistically insignificant for the periods 1963–1979 and 1980–1998. Analysis of the residuals from the multiple‐regression model, which relates fluctuations in the measured daily UV doses (erythemally weighted) at Belsk with those in total ozone and global radiation (surrogate for the cloud and/or aerosol property variations) for the period 1993–1998, reveals that a 0.1 decrease (increase) of the ratio manifests as ∼ 2–3% increase (decrease) of the daily dose relative to its normal value. Extreme change in the vertical structure of the atmosphere yields about a 5% change in the UV daily dose. The simulations by means of a radiative transfer model also show that possible changes of the vertical structure of the atmosphere are rather a minor source of day‐to‐day variations in surface UV radiation. It is suggested that the temporal variations of the ratio may give an insight into the year‐to‐year variations of dynamical processes affecting total ozone content in the Northern Hemisphere midlatitudes.