ИСТИНА

Abstract: Long-term UV measurements and reconstruction modelling in Moscow revealed distinct long-period changes over the period from 1968 to 2015 in both, UV 300-380nm and erythemal irradiance. They are characterized by a pronounced decrease at the end of the 1970s and since 1979 - a statistically significant positive trend of more than 5% per decade growth for erythemal irradiance and of about 3% per decade increase - for UV 300-380nm irradiance. The positive trend in erythemal irradiance is shown to be associated mainly with a decrease in the effective cloud amount, total ozone content, and aerosol optical thickness. We show that due to these changes, there are distinct changes in UV resources especially in spring from the UV optimum to UV moderate excess category for the population with the most vulnerable skin type 1. The model experiments using the INM-RSHU chemistry climate model were fulfilled for several scenarios with different natural and anthropogenic scenarios. We have revealed that anthropogenic emissions of halogens have the most significant impact on negative changes in ozone, and, hence, increase erythemal irradiance. We also show that among natural factors, noticeable effects are observed due to volcanic aerosol and sea surface temperature. The simulations in UV cloud transmittance in INM-RSHU model are generally consistent with the measurements in absolute value except cold period. However, actual values of positive UV irradiance trends regulated by decrease in effective cloud amount are not reproduced well in INM-RSHU model.