Impacts Of Meteorological Conditions On Aerosol Radiation Effects In Different Stations Of Beijing

Spatiotemporal variation characteristics of short-wave solar radiation,many kinds of meteorological elements,PM₁₀ and PM_2.5 concentration,Aerosol Optical Depth?AOD?and their differences between urban and suburban districts are investigated based on observed data of global?GHI?and direct?DIR?radiation,wind speed,wind direction,relative humidity,pressure,air temperature from four weather stations of Beijing and PM₁₀,PM_2.5 concentration,AOD from their surrounding environmental monitor stations.Temporal variation relationship between global radiation and PM₁₀,PM_2.5 concentration and AOD are researched.Furthermore,referring to the other research method,the shortwave radiation fluxes on the ground at four stations in Beijing are calculated using the second Sun-Edward-Slingo radiative transfer?SES2?model and cloud and vapor data from European Centre for Medium-Range Weather Forecasts reanalysis dataset?ECMWF-thin?with 0.125°×0.125°spatial resolution from January,2013 to October,2015.And aerosol radiation effects?ARE?and its difference between urban and suburban district are analyzed compared with observation data on the surface.The quantitative models between deduction ratios of GHI caused by aerosol and PM₁₀ and PM_2.5 concentrations in the urban and suburb of Beijing are established.We focus on impacts of wind speed,wind direction,relative humidity,planetary boundary layer?PBL?height on ARE in the urban,suburban and outer suburban districts of Beijing and its differences.Results showed that temporal variation characteristics of monthly averaged GHI in four stations are consistent.Monthly GHI at Nanjiao?NJ?and Shangdianzi?SDZ?station which are located at suburban and out suburban district are lightly higher than those at Haidian?HD?and Shijingshan?SJS?station located at urban district,especially differences of GHI between urban and suburban district in spring,summer and winter seasons are larger.For polluted days,monthly GHI at SDZ is larger than those at other three stations,namely ARE in urban and suburban districts are higher than those in outer suburban district.There are obvious seasonal variation characteristics for PM₁₀ and PM_2.5.Namely PM₁₀ and PM_2.5 concentrations in autumn and winter are higher than those in spring and summer.Additionally,PM₁₀ and PM_2.5 concentrations in SDZ are far larger than those in other three stations.Among four stations,PM₁₀ and PM_2.5.5 in NJ are largest,HD and SJS take second place,and those in SDZ are smallest.AOD in NJ is larger than that in SDZ,especially for those in autumn and winter.Averaged AOD during 2013²015 in NJ are higher by 0.2 than those in SDZ,and maximum AOD are higher by 0.6.Monthly variation of PM₁₀ and PM_2.5 concentrations and their differences between urban and suburban districts are the opposite of GHI under polluted conditions because of short-wave radiation are absorbed and scattered by aerosol.ARE on the synoptic scale in the urban are about twice that at SDZ,and those in South and west are larger than other areas.GHI reductions caused by aerosol fall in between 146.23 and180.99W·m-² in clear sky and those in cloudy days fall in between 202.11 and 217.02 Wm-²,and differences of GHI deduction in different districts of Beijing in clear sky are larger than those in cloudy days.ARE in autumn and winter which concentrations of PM₁₀ and PM_2.5 are higher in the same period are obviously lager than those in spring and summer.Reduction ratios of GHI in the southern suburbs of Beijing in autumn and winter are higher by 10²0%than those in spring and summer during 2013²015,and maximum deduction ratio is 60%.ARE at SDZ in clear days are distinctly smaller than those at other three stations.Among four stations,ARE at HD and SJS are larger and it is related with difference of pollution level and meteorological conditions,and impacted differences of region transport of pollutants from outside.When PM_2.5 concentration is smaller than 350?g.m-³ in cloudy days,differences of ARE at four stations is also small.But when PM_2.5 concentration is large than the above threshold,ARE will increase remarkably.It may be caused by hygroscopic growth of aerosol in cloudy days.Linear relationship between reduction ratios of the GHI,DIR and AOD in the urban and suburban districts of Beijing are founded and impacts of AOD on DIR are larger than GHI,especially in the urban district with heavy haze.Additionally impacts of PM_2.5 concentration on GHI and DIR are not ignored.Impacts of wind speed,wind direction and relative humidity on ARE on the synoptic scale are very important.And impacts of wind speed and relative humidity on ARE in the outer surburban district are larger than those in the urban and suburb district of Beijing.Wind speed is small and relative humidity is high in the urban and suburb district in the autumn and winter,thus they will aggravate generation and growth of aerosol and indirectly affects ARE.Impacts of wind speed and relative humidity on ARE is different.Namely,impacts of relative humidity on ARE in the urban and suburb district is more consistent,but there are differences between effects of wind speed on ARE in the urban and suburban districts.Results of this study have certain scientific and practical application values for better understanding the interaction between aerosol,cloud and solar radiation,and improvements of observation and forecasts of environment meteorological conditions and refined assessments and predictions of solar energy resources.