Investigation of Atmospheric Transmission in the Crimea (Ukraine) in the Twentieth Century

Abstract

Systematic monitoring of spectral atmospheric transmission (SAT) has been conducted in the Crimea (a peninsula in Ukraine) since 1996. A sun-tracking solar photometer that records signals in five spectral regions selected by interference filters centered at 357, 401, 448, 512, and 750 nm, respectively, is used for this purpose. The SAT values obtained during 1996?2000 are compared with the results of earlier studies conducted in the Crimea in 1924?32 (the first observation period) and 1972?90 (the second observation period). The following conclusions can be reached based on this comparison. 1) During the first period of observations after the civil war in 1924?32, there was no industry in the Crimea. Therefore, the atmospheric transmission for this period can be assumed to be at a background level. The second, industrial, period is characterized by a maximum in the anthropogenic influence on the environment. A noticeable decrease in SAT was observed during that period. The third period, after the ?perestroika,? showed background levels again. 2) During all three observational periods, the seasonal cycle of the atmospheric transmission was stable, indicating that natural processes dominated over anthropogenic influences. 3) A considerable decrease in the atmospheric transmission that was observed in 1982?83 was evidently related to the El Chichón volcano eruption in Mexico in the spring of 1982.