Development And Application Of Ground Aerosol Mobile Integrated Observation System

Atmospheric aerosol is believed to have a significant influence on climate change,and it plays an important role in earth-atmosphere system.Atmospheric aerosols in different regions consist of varying composition and distribution,which lead to its different radiative impacts on regional climate.There are still a lot of uncertainties about Atmospheric aerosols so far,and it is one of the main focuses in recent research.One of the important sources of atmospheric aerosols is agricultural activities,especially during periods of high wind speed or agricultural land preparation activities.Dust from Gobi desert is another important source of atmospheric aerosols.Dust aerosols can mix with anthropogenic aerosols during long-range transmission,and this will make the climate effects of aerosol more complex and uncertain.For the reason of better understanding the properties of mixed aerosol,it is essential to study the aerosol properties in dust source regions.A lot of studies have been done in the fields of aerosol so far,including numerical simulation,satellite remote sensing and ground-based observations.Ground-based observations can correct the errors of satellite retrieve products,and parameters from satellite remote sensing and,ground-based observations can be used to improved modes.The best way to correct the error is to set up observational stations on different representative ground surfaces,and it will cost much money and energy.To better solve this problem,we need a ground aerosol mobile integrated observation system,which we can easily transport to the field campaign site.We explored design projects and modified ideas of container for the first time,and a new container that is used to carried aerosol field campaign would be made.The side door and wire outlets were designed on the two sides,and observation and sample inlet holes were designed on the roof.The space where place the air-conditioning machine was set up outside the container.We improved container safety performance effectively by strengthening the container wall insulation and fire effect,using the explosion-proof lighting facilities and circuits.All these measures could make container more suitable for harsh observation environments and easier to carry out field campaign.The interior space of container was optimizing and rationally used by setting up equipment rack that instruments and spare parts were fixed on,so these measures would simplify the progress of packing and installation work,and ensure the safety during transport.We putted aerosol observation instruments into the container equipment cabinets,so the space was used reasonably and effectively.Sampling gas from sampling tube was split into several gas streams.The impactors were installed in each gas stream tube inside the container,thus it could obtain different size aerosols.The flow rate of each gas steam must be calculated accurately to ensure the impactors and instruments normal running.Instruments will be well integrated in series or parallel,which can be essential for the contrast and mutual verification among the instruments.In order to obtain high quality observation data,the check and calibration of instruments of aerosol observing system were discussed.The cycle of leakage and flow rate check was 3 months or before the field campaign.It was necessary to check tubing and exhaust pump if the error of flow rate exceeded 5%.Leak check mainly included sampling pipes,exhaust pipes,impactors and instruments and so on.Check and calibration of nephelometer was in-depth discussed.Zero checking was done every two days,and zero set was done if ranges of scattering coefficient and average values were out of ±3Mm-1 and ± 1.5 Mm-1,respectively.Span check was done every week,and span calibration was done if the scattering coefficient error between average and theoretical calculation was greater than 5%.In order to facilitate to check and calibrate nephelometer,we have made some modifications to it.In order to check and improve the newly developed ground aerosol mobile integrated observation system,and better study aerosol properties in the agricultural areas during farming season and Gobi areas in northwestern China,an field campaign about aerosols of agricultural and Gobi regions was carried out in Hexi Corridor from April to May in 2014,and the ground aerosol observing system has been in use.In Huangyangzhen Farm,Linze Farm and Dunhuang Gobi region,scattering coefficients of PM2.5 were 98.20±38.29,170.33±407.29 and 52.71±43.02Mm-1,and the values of PM1.0 were 74.631±29.07,116.72±259.89 and 24.65±16.80Mm-1,respectively.During dust storm in Linze Farm,Scattering coefficients of PM2.5 and PM1.0 were 981.69±944.79Mm-1 and 649.82±586.46Mm-1,respectively.Absorption coefficients of PM2.5 in three sites were 8.81±6.28,5.72±4.93 and 2.11±1.02Mm-1,respectively,and the mass concentrations of PM25 aerosol were 35.62± 16.63,103.86±294.05 and 46.04±33.72?g/m3,respectively.During dust storm in Linze Farm,absorption coefficient and mass concentration were 5.24±4.23Mm-1 and 42.74±40.42?g/m3,respectively.The values of scattering and absorption coefficients and mass concentration in three sites were less than the values of cities in eastern China.SSA in three sites was 0.899±0.031,0.929±0.041 and 0.949±0.022,respectively.During and not considering dust storm in Linze Farm,SSA was 0.988±0.004 and 0.922±0.038,respectively.Mass scattering efficiency in three sites were 2.709±0.674,2.111±0.828 and 1.491±0.878m2/g,respectively.Single scattering albedo in two sites was greater than the values in urban areas,while the mass scattering efficiency was smaller.Scattering Angstrom exponent of PM2.5 in three sites were 1.310±0.293,0.777±0.535 and 0.527±0.331,respectively,and the values of PM1.0 were 2.098±0.237,1.048±0.671 and 0.867±0.448,respectively.During the duststorm in Linze Farm,the scattering Angstrom exponent was smaller than usual,and values of PM2.5 and PM1.0 were-0.039±0.020 and-0.147±0.060,respectively.Without considering dust storm,scattering Angstrom exponents of PM2.5 and PM1.0 were 0.869±0.486 and 1.182±0.567,respectively.The aerodynamic size distributions in Huangyangzhen Farm and Linze Farm sites were mainly less than 2.5?m,and in Dunhuang Gobi was mainly less than 5?m.Aerosol concentration below 1?m and aerosol absorption in Huangyangzhen Farm was the strongest among three sites.Aerosols in Huangyangzhen Farm got more anthropogenic impact,and aerosols in Dunhuang Gobi included more dust aerosols and less anthropogenic aerosols.The peak values of scattering coefficient and absorption coefficient and mass concentration appeared in the morning and evening in Huangyangzhen Farm and Linze Farm and Dunhuang Gobi.The peak values mainly related to human activities.In the morning,human activities increased and the atmosphere was relatively stable,and these were not conducive to spread of air pollutants.In the evening,atmospheric vertical motion decreased,and it was conducive to accumulate aerosols near the ground.The valley values appeared in the afternoon and night in Huangyangzhen Farm and Linze Farm.The diffusion of aerosols in late evening made the aerosol concentration decrease,and valley values appeared.In the daytime,convection activities of air were conducive to diffusion of aerosols,and aerosol concentration was minimal in the afternoon.SSA and mass scattering efficiency appeared valley values when the scattering coefficient appeared peak values in Huangyangzhen Farm and Linze Farm.The diurnal variation of aerosol properties was not significantly in Dunhuang Gobi,and diurnal variation of SSA and scattering Angstrom exponent was relatively flat,and that showed the type of aerosol was simple.HYSPLIT-4 model was used to analysis the main source of aerosols.In Hunagyangzhen Farm,air mass streams were mainly from southeast and back trajectory streams of 36h and 48h accounted for 55%and 52%,respectively.Followed by local air masses,back trajectory streams of 36h and 48h accounted for 25%and 32%,respectively,and some air masses were from Tengger Desert.In Linze Farm,the main air masses were from Badain Jaran Desert,and back trajectory streams of 36h and 48h accounted for 64%and 58%,respectively,and followed by northwest and southeast air masses.During dust period in Linze Farm,the main air masses were from Gobi and Taklimakan desert.During floating dust time,the main air masses were from southeast,and back trajectory streams of 36h and 48h accounted for 71%and 58%,respectively.In Dunhuang Gobi,air mass streams of 36h were mainly from location,and back trajectory streams of 500m and 1000m accounted for 55%and 52%,respectively.Local blowing dust was the main source of aerosol,and then from Kumtag desert.Some air mass streams of 500m were from the Altai Mountain in Mongolia and Tianshan Mountain in Xinjiang,and some air mass streams of 1000m were from Gurbantonggut desert in Xinjiang.Air mass streams of 48h were mainly from Gobi in the north of Dunhuang site,and back trajectory streams of 500m and 1000m accounted for 40%and 69%,respectively.Some air mass streams of 500m were from Kumtag desert that accounted for 40%and some were from Gurbantonggut desert.Some air mass streams of 1000m were from the Qaidam Basin in Qinghai and Gurbantonggut desert.