Spatial-temporal Distribution Of Absorptive Aerosols And Its Effect On Ultraviolet Radiation In The Yangtze Rive Delta

Aerosols-radiation interaction has always been a topic of general interest in the study of atmospheric environment and climate change research.Aerosols affect the ground-gas system radiation balance by absorbing and scattering solar radiation.Although aerosols generally have negative radiative forcing on the global climate,they are absorbed in aerosols.The black carbon aerosol exhibits a pronounced positive radiative forcing,which produces a climatic effect similar to that of greenhouse gases.Therefore,absorptive aerosols are one of the major uncertainties in accurately assessing and predicting global climate change.Although ultraviolet radiation accounts for only 7 percent of the solar radiation,it has enormous impacts on human health and the ecological environment.Excessive ultraviolet irradiation increases the incidence of skin cancer and cataract,destroys the photosynthesis of plants,and induces photochemical reactions.Therefore,it is significant realistic meanings and scientific value to study the temporal-spatial distribution of absorptive aerosols and its effect on ultraviolet radiation.This paper selects the OMI/Aura OMAERUV L2 aerosol dataset from 2008 to 2017 and the UV radiation dataset of the Chinese Ecosystem Research Network from 2008 to 2015 to study the temporal-spatial distribution of the absorptive aerosols in the Yangtze River Delta and its effect on ultraviolet radiation.Combined with the NCAR TUV radiation transmission mode,the quantitative effects of aerosol optical parameters(AOD and SSA)on ultraviolet radiation were studied deeply.The results are as follows:(1)In the temporal distribution,the inter-annual variation of absorptive aerosol optical depth(AAOD)that increased first and then decreased,reaching the highest value was 0.056 at 2011 was consistent with the aerosol optical depth(AOD)was 0.702 in the Yangtze River Delta.The inter-monthly variation shows that the high value of AAOD appeared mostly in January,March and June,and increased significantly from November to January.In the spatial distribution,the AAOD was higher in the north than south in the Yangtze River Delta,and the AOD was similar with the AAOD.The high values of AAOD above 0.05 were mainly concentrated in northern Anhui and Jiangsu provinces,and Nanjing,Hangzhou,and Jinhua.The seasonal spatial distribution of AAOD and AOD is higher in spring and winter,and lower in autumn,but the difference between the two was that AOD is very high in summer and AAOD is low.The contribution of black carbon in the Yangtze River Delta was consistent with the annual spatial distribution of the AAOD and AOD.(2)Among the two ground stations,the ultraviolet radiation value of Tai Lake station is higher.The annual change shows that UV radiation has a significant downward trend in June.The main reason is that the Jiangnan area is in the rainy season.At the end of the rainy season,the UV radiation value in July and August rebounds and is the highest in a year,and UV radiation in November and December at a lower level.The seasonal variation of ultraviolet radiation are more significant,summer is the highest,spring is the second,followed by autumn and the last is winter.Ultraviolet radiation reaches the maximum at 12 noon.(3)The TUV radiation transmission mode simulates the change of ultraviolet radiation more accurately,and the mode simulation result is always higher than the actual ultraviolet radiation from the observations.The May 12 and July 28 represented in spring and summer UV radiation from ground observations are similar to model simulations.The results obtained by simulation on October 15 and January 8 represented in autumn and winter at 10 to 14 hours are significantly higher than the actual observed ultraviolet radiation values.The model simulation result is always higher than the actual observation results for three reasons.First,under the actual observation conditions,the influence of the cloud cannot be completely avoided.Second,since the actual measurement has a half-width transmission band,the actual measured ultraviolet radiation value is not the value under the ideal band.Third,it is related to the degree of atmospheric pollution in the actual environment.Under normal circumstances,sulfur dioxide and nitrogen oxides in the atmospheric environment are underestimated when the air pollution is serious.(4)The correlation coefficient between AOD and ultraviolet radiation is-0.591,the correlation coefficient between SSA and ultraviolet radiation is 0.504.When the wavelength is less than 300 nm,the ultraviolet radiation reaching the ground is substantially zero due to the absorption of the ozone layer in the stratosphere.In the 300 to 330 nm band,the ultraviolet radiation increases greatly,aerosols effect on ultraviolet radiation is large,and ultraviolet radiation is more sensitive.The ultraviolet radiation that reaches the ground after 330 nm grows very slowly,and the ultraviolet radiation sensitivity is not high in this band.Whenever the AOD increases by 0.2,the UV radiation is weakened by nearly 11% at 12 noon.When the SSA is lowered by 0.05,the ultraviolet radiation is attenuated by nearly 6% at 12 noon.The ultraviolet radiation content of Tai Lake station reaching the ground is always higher than that of Changshu station.When the wavelength is above 355 nm,the ultraviolet radiation variation of Tai Lake station is more significant than that in Changshu station.