DEPENDENCE OF ATMOSPHERIC TRANSPARENCY VARIATIONS ON SOLAR-ACTIVITY

The atmospheric spectral transparency variations at 344 nm and 369 nm averaged at eight Soviet stations between 69 degrees N mid 55 degrees N, have been compared with sunspot numbers, or Wolf numbers (WN). The data were taken for the seasonal interval May-August during the period 1972-1989. Good negative correlations -0.76 and -0.82 have been found . The correlation coefficient between aerosol extinction at 344 nm and WN is equal to +0.75. Insignificant correlation is found for the tran sparency variations of 344 nm for stations situated to the south of la titude 50 degrees. The best correlation with WN for both transparency and aerosol extinction at northern stations occurs for the shift of WN ahead of the optical parameters by 6 months. The connection of transp arency with cosmic rays in Apatity is also examined. It displays a sig n opposite to that for WN, smaller values of the correlation coefficie nt, and an improbable shift of transparency ahead of cosmic ray intens ity. The relative changes of the transparency during a solar cycle can be evaluated at 10% in the ozone-free UVA region.