Analysis and Study on Long Term Variation Characteristics of Ultraviolet Radiation in Beijing Area

This article uses radiation data observed in the Beijing area from 2005 to 2020 to reveal the changing patterns of ultraviolet radiation (UV) in the past decade. At the same time, the main factors affecting the long-term changes of ultraviolet radiation in the Beijing area are analyzed. The results show that UV radiation shows obvious daily and seasonal variation trends. The daily variation shows a single-peak variation pattern, with the maximum value of the day occurring at noon (16.26 W m⁻²) and low values occurring in the morning and evening minimum value (5.64 W m⁻²) occurring at 0800 BJT. UV radiation gradually increases from spring to the maximum value of the year in summer and then starts to decrease until the minimum value of the year in winter, with the monthly average maximum and minimum values being in June (12.17 W m⁻²) and December (5.4 W m⁻²), respectively. The annual average UV radiation is 9.74 W m⁻². UV radiation shows a positive correlation with the clearness index and a negative correlation with the aerosol optical depth and atmospheric PM_2.5 (fine particulate matter).