This paper retrieves the yearly and monthly mean 0.75μm aerosol optical depth(AOD)of 41 A-class solar radiation stations over China from 1979 to 1990,and analyzes the spatial and temporal distribution of AOD over Chi...This paper retrieves the yearly and monthly mean 0.75μm aerosol optical depth(AOD)of 41 A-class solar radiation stations over China from 1979 to 1990,and analyzes the spatial and temporal distribution of AOD over China mainland.The data employed are daily direct solar radiation and sunshine duration,as well as the TOMS version-7 ozone observation data in the same time.The results indicate that the Siehuan Basin is the largest center of yearly mean AOD over China.and the other two larger centers lie in Wuhan City and the South Xinjiang Basin, separately.AOD values are also relatively larger in the middle-and-lower reaches area of Changjiang River.Shandong Peninsula and coastal area of Guangdong Province:while in Yunnan Province,coastal area of Fujian Province.most parts of Northwest and Northeast China,AOD values are relatively smaller.The distribution of AOD varies with different months.In most parts of China.the maximum of AOD occurs in spring season;but the minimum varies in different regions,From 1979 to 1990.in the Qinghai-Xizang Plateau,West Siehuan Basin,North Guizhou Province.most areas of the middle-and-lower reaches of Changjiang River,Shandong Peninsula and west part of South Xinjiang Basin.AOD shows an increasing trend.But in Northeast China, most part of Northwest China,Yunnan-Guizhou Plateau,western Guangxi Region and the coastal areas of East China,AOD shows decreasing tendency.Generally,the seasonal variation characteristics of AOD in China can be classified into four typical models,i.e.,mono-modal types A and B,bimodal and Poly-modal.展开更多
This paper analyzes the correlation between variations of total and low cloud amounts and the varying features of aerosols related to urban development of Beijing by using the cubic spline fitting method based on the ...This paper analyzes the correlation between variations of total and low cloud amounts and the varying features of aerosols related to urban development of Beijing by using the cubic spline fitting method based on the monthly meteorological data of temperature,humidity,precipitation,clouds,and aerosol optical depth （AOD） during 1950-2005.The statistics on the development of the city of Beijing in this period,including the total industrial output,population,residential housing development,highway construction,charcoal production,etc.,is revealed.Accompanying the rapid urban development of Beijing over the past 55 years or so,the urban aerosol concentration and composition have changed.The results indicate that：1） there is a general trend of climate warming and drying in Beijing;2） the total cloud amount in all seasons declines drastically,but lower cloud amount climbs up slightly;3） the high correlations between cloud amount and the indices of Beijing urban development such as the housing area,charcoal production,and road construction show that the variation of cloud amount is closely related to the urban development;4） the changing trend of AOD coincides more closely with the variation of low cloud amount.The evident drop of total cloud amount is in agreement with the trend of climate warming and drying,while the slight growth of low cloud amount is likely caused by more haze and fog occurrences in the lower troposphere in association with the pollution responsible for the＂darkening＂of Beijing and the surrounding areas.展开更多
Increasing attention has been paid to the deterioration of air quality in China during the past decade.This study presents the spatiotemporal variations of aerosol concentration across China during 2000–2016 using ae...Increasing attention has been paid to the deterioration of air quality in China during the past decade.This study presents the spatiotemporal variations of aerosol concentration across China during 2000–2016 using aerosol optical depth(AOD)from the atmospheric product of Moderate Resolution Imaging Spectroradiometer.Percentile thresholds are applied to define AOD days with different loadings.Temporally,aerosol concentration has increased since 2000 and reached the highest level in 2011;then it has declined from 2011 to 2016.Seasonally,aerosol concentration is the highest in summer and the lowest in winter.Spatially,North China and Sichuan Basin are featured by high aerosol concentration with increasing trends in North China and decreasing trends in Sichuan Basin.North,Southeast and Southwest China have been through increasing days with low AOD loading;however,Northeast China has experienced increasing days with high AOD loading.It is likely that air quality influenced by aerosols has notably improved over North China in spring and summer,over Southwest and Southeast China in autumn,but has degraded over Northeast China in autumn.展开更多
Although the concentration of atmospheric particulate matter in Shanghai has declined in recent years,aerosols remain one of the major pollutants affecting air quality.Herein,spatio-seasonal variation in aerosol optic...Although the concentration of atmospheric particulate matter in Shanghai has declined in recent years,aerosols remain one of the major pollutants affecting air quality.Herein,spatio-seasonal variation in aerosol optical properties and aerosol types were studied overa 10-year period(2006-2015)in Shanghai,China,using satellite data from Moderate Resolution Imaging Spectroradiometer(MODIS)and CloudAerosol Lidar with Orthogonal Polarization(CALIOP).The average aerosol optical depth values for central urban and suburban areas of Shanghai were between 0.9 and 1.0.Clear seasonal variation in aerosol concentrations occurred,causing strongest attenuation in summer and weakest attenuation in autumn.Polluted dust,polluted continental(urban/industrial)and smoke aerosols were the main aerosol types.Desert dust aerosols occurred in the Shanghai area at higher altitudes(greater than 3 km)in spring,related to dusty weather in the north;while in winter,smoke aerosols occurred at high altitudes,related to haze pollution in the north.The aerosols detected in autumn were mainly from local sources,comprising polluted dust,polluted continental,and smoke aerosols.Aerosols in Shanghai clearly reflect both local and regional sources at different times.展开更多
Depending on various government policies,COVID-19(Corona Virus Disease-19) lockdowns have had diverse impacts on global aerosol concentrations.In 2022,Changchun a provincial capital city in Northeast China,suffered a ...Depending on various government policies,COVID-19(Corona Virus Disease-19) lockdowns have had diverse impacts on global aerosol concentrations.In 2022,Changchun a provincial capital city in Northeast China,suffered a severe COVID-19 outbreak and implemented a very strict lockdown that lasted for nearly two months.Using ground-based polarization Light Detection and Ranging(LiDAR),we detected real-time aerosol profile parameters(EC,extinction coefficient;DR,depolarization ratio;AOD,aerosol optical depth),as well as air-quality and meteorological indexes from 1 March to 30 April in 2021 and 2022 to quantify the effects of lockdown on aerosol concentrations.The period in 2022 was divided into three stages:pre-lockdown(1-10 March),strict lockdown(11 March to 10 April),and partial lockdown(11-30 April).The results showed that,during the strict lockdown period,compared with the pre-lockdown period,there were substantial reductions in aerosol parameters(EC and AOD),and this was consistent with the concentrations of the atmospheric pollutants PM_(2.5)(particulate matter with an aerodynamic diameter ≤2.5 μm) and PM_(2.5)(particulate matter with an aerodynamic diameter ≤10 μm),and the Oconcentration increased by 8.3%.During the strict lockdown,the values of EC within0-1 km and AOD decreased by 16.0% and 11.2%,respectively,as compared to the corresponding period in 2021.Lockdown reduced the conventional and organized emissions of air pollutants,and it clearly delayed the time of seasonal emissions from agricultural burning;however,it did not decrease the number of farmland fire points.Considering meteorological factors and eliminating the influence of wind-blown dust events,the results showed that reductions from conventional organized emission sources during the strict lockdown contributed to a 30% air-quality improvement and a 22% reduction in near-surface extinction(0-2 km).Aerosols produced by urban epidemic prevention and disinfection can also be identified using the EC.Regarding seasonal sources of agricultural s展开更多
Background:To study,estimate and discuss the variations of the aerosol optical depth(AOD),black carbon,sulfate and organic matter,in the atmosphere in Blida City of Algeria,which was greatly affected by COVID-19 pande...Background:To study,estimate and discuss the variations of the aerosol optical depth(AOD),black carbon,sulfate and organic matter,in the atmosphere in Blida City of Algeria,which was greatly affected by COVID-19 pandemic.Methods:We analyzed the effects of changes in the total AOD,black carbon,sulfate,and organic matter in the atmosphere(λ=550 nm)in the same period of 2019 and 2020,following the COVID-19 epidemic in Blida City,which was the most-affected city in Algeria.Results:The quarantine that was enacted to limit the spread of COVID-19 resulted in side effects that were identifiable in the total AOD and in some of its atmospheric components.Comparing these variables in 2019 and 2020(in the months during the quarantine)revealed that in April,the BCAOD values were much lower in 2020than in 2019.Conclusion:Based on the effects of the emerging COVID-19,the research listed the changes received from the AOD,and is considered as a comparative study and represents a significant side effect of the quarantine that was mainly designed to limit COVID-19.展开更多
Atmospheric aerosols have effects on atmospheric radiation assessments,global climate change,local air quality and visibility.In particular,aerosols are more likely transformed and accumulated in winter.In this paper,...Atmospheric aerosols have effects on atmospheric radiation assessments,global climate change,local air quality and visibility.In particular,aerosols are more likely transformed and accumulated in winter.In this paper,we used the Multi-Axis Differential Optical Absorption Spectroscopy(MAX-DOAS)instrument to study the characteristics of aerosol type and contributions of PM_(2.5) chemical components to aerosol extinction(AE),vertical distribution of aerosols,and source.From December 30,2018 to January 27,2019,we conducted MAX-DOAS observations on Sanmenxia.The proportion of PM_(2.5) to PM10 was 69.48%-95.39%,indicating that the aerosol particles were mainly fine particles.By analyzing the ion data and modifying Interagency Monitoring of Protected Visual Environments(IMPROVE)method,we found that nitrate was the largest contributor to AE,accounting for 31.51%,28.98%,and 27.95%of AE on heavily polluted,polluted,and clean days,respectively.NH4+,OC,and SO42-were also major contributors to AE.The near-surface aerosol extinction retrieved from MAX-DOAS measurement the PM_(2.5) and PM10 concentrations measured by an Unmanned Aerial Vehicle(UAV)have the same trend in vertical distribution.AE increased about 3 times from surface to 500 m.With the backward trajectory of the air mass during the haze,we also found that the continuous heavy pollution was mainly caused by transport of polluted air from the northeast,then followed by local industrial emissions and other sources of emissions under continuous and steady weather conditions.展开更多
The accuracy of MODIS aerosol products from the NASA Terra Satellite is validated in comparison with the results of sun-photometer observations in Beijing and Hong Kong. By analyzing the MODIS aerosol products within ...The accuracy of MODIS aerosol products from the NASA Terra Satellite is validated in comparison with the results of sun-photometer observations in Beijing and Hong Kong. By analyzing the MODIS aerosol products within the period of August 2000 to April 2003, it is believed that human activities are the main source of aerosols in the eastern part of China. This is based on the facts that all areas with relatively high values are consistent with regions of dense population and fast economic development, such as the North China Plain, the Sichuan Basin and the Pearl River Delta. It is also supported by the distribution of 舗gstr鰉 exponents showing that most aerosols in the eastern part of China are closely related to human activities, excepting the strong sandstorm episodes occurring in spring, fall and winter. In contrast to developed countries, the 舗gstr鰉 exponent of urban area in China is lower than its surroundings, indicating that the contribution of local floating dust and soot attributed to human activities is significant. Results presented in this paper provide important data for further research on climatic change and environmental study.展开更多
文摘This paper retrieves the yearly and monthly mean 0.75μm aerosol optical depth(AOD)of 41 A-class solar radiation stations over China from 1979 to 1990,and analyzes the spatial and temporal distribution of AOD over China mainland.The data employed are daily direct solar radiation and sunshine duration,as well as the TOMS version-7 ozone observation data in the same time.The results indicate that the Siehuan Basin is the largest center of yearly mean AOD over China.and the other two larger centers lie in Wuhan City and the South Xinjiang Basin, separately.AOD values are also relatively larger in the middle-and-lower reaches area of Changjiang River.Shandong Peninsula and coastal area of Guangdong Province:while in Yunnan Province,coastal area of Fujian Province.most parts of Northwest and Northeast China,AOD values are relatively smaller.The distribution of AOD varies with different months.In most parts of China.the maximum of AOD occurs in spring season;but the minimum varies in different regions,From 1979 to 1990.in the Qinghai-Xizang Plateau,West Siehuan Basin,North Guizhou Province.most areas of the middle-and-lower reaches of Changjiang River,Shandong Peninsula and west part of South Xinjiang Basin.AOD shows an increasing trend.But in Northeast China, most part of Northwest China,Yunnan-Guizhou Plateau,western Guangxi Region and the coastal areas of East China,AOD shows decreasing tendency.Generally,the seasonal variation characteristics of AOD in China can be classified into four typical models,i.e.,mono-modal types A and B,bimodal and Poly-modal.
基金Supported by the Special Grant in Atmospheric Sciences of the China Meteorological Administration(GYHY200706036)the National"973"Program of China(2011CB403404)the International Cooperation Project on Monsoon Monitoring (200 9DFA21430)
文摘This paper analyzes the correlation between variations of total and low cloud amounts and the varying features of aerosols related to urban development of Beijing by using the cubic spline fitting method based on the monthly meteorological data of temperature,humidity,precipitation,clouds,and aerosol optical depth （AOD） during 1950-2005.The statistics on the development of the city of Beijing in this period,including the total industrial output,population,residential housing development,highway construction,charcoal production,etc.,is revealed.Accompanying the rapid urban development of Beijing over the past 55 years or so,the urban aerosol concentration and composition have changed.The results indicate that：1） there is a general trend of climate warming and drying in Beijing;2） the total cloud amount in all seasons declines drastically,but lower cloud amount climbs up slightly;3） the high correlations between cloud amount and the indices of Beijing urban development such as the housing area,charcoal production,and road construction show that the variation of cloud amount is closely related to the urban development;4） the changing trend of AOD coincides more closely with the variation of low cloud amount.The evident drop of total cloud amount is in agreement with the trend of climate warming and drying,while the slight growth of low cloud amount is likely caused by more haze and fog occurrences in the lower troposphere in association with the pollution responsible for the＂darkening＂of Beijing and the surrounding areas.
基金supported by a Natural Sciences and Engineering Research Council of Canada(NSERC)Discovery Grant and Ontario Trillium Scholarship.
文摘Increasing attention has been paid to the deterioration of air quality in China during the past decade.This study presents the spatiotemporal variations of aerosol concentration across China during 2000–2016 using aerosol optical depth(AOD)from the atmospheric product of Moderate Resolution Imaging Spectroradiometer.Percentile thresholds are applied to define AOD days with different loadings.Temporally,aerosol concentration has increased since 2000 and reached the highest level in 2011;then it has declined from 2011 to 2016.Seasonally,aerosol concentration is the highest in summer and the lowest in winter.Spatially,North China and Sichuan Basin are featured by high aerosol concentration with increasing trends in North China and decreasing trends in Sichuan Basin.North,Southeast and Southwest China have been through increasing days with low AOD loading;however,Northeast China has experienced increasing days with high AOD loading.It is likely that air quality influenced by aerosols has notably improved over North China in spring and summer,over Southwest and Southeast China in autumn,but has degraded over Northeast China in autumn.
基金The MODIS and CALIOP data were obtained from NASA's Level-1 and Atmosphere Archive&Distribution System Distributed Active Center(LAADS DAAC)and Atmospheric Science Data Center(ASDC),respectively.This work was supported by the Major Research Plan of the National Natural Science Foundation of China(Grant No.91644211)the Fundamental Research Funds for the Central Universities(Grant No.2232019D3-27)+1 种基金the China Postdoctoral Science Foundation(Grant No.2019M651322)and the National Natural Science Foundation of China(Grant Nos.41905131 and 91637101).
文摘Although the concentration of atmospheric particulate matter in Shanghai has declined in recent years,aerosols remain one of the major pollutants affecting air quality.Herein,spatio-seasonal variation in aerosol optical properties and aerosol types were studied overa 10-year period(2006-2015)in Shanghai,China,using satellite data from Moderate Resolution Imaging Spectroradiometer(MODIS)and CloudAerosol Lidar with Orthogonal Polarization(CALIOP).The average aerosol optical depth values for central urban and suburban areas of Shanghai were between 0.9 and 1.0.Clear seasonal variation in aerosol concentrations occurred,causing strongest attenuation in summer and weakest attenuation in autumn.Polluted dust,polluted continental(urban/industrial)and smoke aerosols were the main aerosol types.Desert dust aerosols occurred in the Shanghai area at higher altitudes(greater than 3 km)in spring,related to dusty weather in the north;while in winter,smoke aerosols occurred at high altitudes,related to haze pollution in the north.The aerosols detected in autumn were mainly from local sources,comprising polluted dust,polluted continental,and smoke aerosols.Aerosols in Shanghai clearly reflect both local and regional sources at different times.
基金the Key Research Program of Frontier Sciences,Chinese Academy of Sciences (No. QYZDB-SSW-DQC045)the National Natural Science Foundation of China (No. 41775116)。
文摘Depending on various government policies,COVID-19(Corona Virus Disease-19) lockdowns have had diverse impacts on global aerosol concentrations.In 2022,Changchun a provincial capital city in Northeast China,suffered a severe COVID-19 outbreak and implemented a very strict lockdown that lasted for nearly two months.Using ground-based polarization Light Detection and Ranging(LiDAR),we detected real-time aerosol profile parameters(EC,extinction coefficient;DR,depolarization ratio;AOD,aerosol optical depth),as well as air-quality and meteorological indexes from 1 March to 30 April in 2021 and 2022 to quantify the effects of lockdown on aerosol concentrations.The period in 2022 was divided into three stages:pre-lockdown(1-10 March),strict lockdown(11 March to 10 April),and partial lockdown(11-30 April).The results showed that,during the strict lockdown period,compared with the pre-lockdown period,there were substantial reductions in aerosol parameters(EC and AOD),and this was consistent with the concentrations of the atmospheric pollutants PM_(2.5)(particulate matter with an aerodynamic diameter ≤2.5 μm) and PM_(2.5)(particulate matter with an aerodynamic diameter ≤10 μm),and the Oconcentration increased by 8.3%.During the strict lockdown,the values of EC within0-1 km and AOD decreased by 16.0% and 11.2%,respectively,as compared to the corresponding period in 2021.Lockdown reduced the conventional and organized emissions of air pollutants,and it clearly delayed the time of seasonal emissions from agricultural burning;however,it did not decrease the number of farmland fire points.Considering meteorological factors and eliminating the influence of wind-blown dust events,the results showed that reductions from conventional organized emission sources during the strict lockdown contributed to a 30% air-quality improvement and a 22% reduction in near-surface extinction(0-2 km).Aerosols produced by urban epidemic prevention and disinfection can also be identified using the EC.Regarding seasonal sources of agricultural s
文摘Background:To study,estimate and discuss the variations of the aerosol optical depth(AOD),black carbon,sulfate and organic matter,in the atmosphere in Blida City of Algeria,which was greatly affected by COVID-19 pandemic.Methods:We analyzed the effects of changes in the total AOD,black carbon,sulfate,and organic matter in the atmosphere(λ=550 nm)in the same period of 2019 and 2020,following the COVID-19 epidemic in Blida City,which was the most-affected city in Algeria.Results:The quarantine that was enacted to limit the spread of COVID-19 resulted in side effects that were identifiable in the total AOD and in some of its atmospheric components.Comparing these variables in 2019 and 2020(in the months during the quarantine)revealed that in April,the BCAOD values were much lower in 2020than in 2019.Conclusion:Based on the effects of the emerging COVID-19,the research listed the changes received from the AOD,and is considered as a comparative study and represents a significant side effect of the quarantine that was mainly designed to limit COVID-19.
基金supported by the National Natural Science Foundation of China (Nos.41530644, 41775029, 41975037)the National Key Research and Development Plan of China (Nos.2018YFC0213201, 2017YFC0209902, 2018YFC0213801)。
文摘Atmospheric aerosols have effects on atmospheric radiation assessments,global climate change,local air quality and visibility.In particular,aerosols are more likely transformed and accumulated in winter.In this paper,we used the Multi-Axis Differential Optical Absorption Spectroscopy(MAX-DOAS)instrument to study the characteristics of aerosol type and contributions of PM_(2.5) chemical components to aerosol extinction(AE),vertical distribution of aerosols,and source.From December 30,2018 to January 27,2019,we conducted MAX-DOAS observations on Sanmenxia.The proportion of PM_(2.5) to PM10 was 69.48%-95.39%,indicating that the aerosol particles were mainly fine particles.By analyzing the ion data and modifying Interagency Monitoring of Protected Visual Environments(IMPROVE)method,we found that nitrate was the largest contributor to AE,accounting for 31.51%,28.98%,and 27.95%of AE on heavily polluted,polluted,and clean days,respectively.NH4+,OC,and SO42-were also major contributors to AE.The near-surface aerosol extinction retrieved from MAX-DOAS measurement the PM_(2.5) and PM10 concentrations measured by an Unmanned Aerial Vehicle(UAV)have the same trend in vertical distribution.AE increased about 3 times from surface to 500 m.With the backward trajectory of the air mass during the haze,we also found that the continuous heavy pollution was mainly caused by transport of polluted air from the northeast,then followed by local industrial emissions and other sources of emissions under continuous and steady weather conditions.
基金supported by the grant NSFC/HKUST36 and the National Natural Science Foundation of China(Grant No.1999045700).
文摘The accuracy of MODIS aerosol products from the NASA Terra Satellite is validated in comparison with the results of sun-photometer observations in Beijing and Hong Kong. By analyzing the MODIS aerosol products within the period of August 2000 to April 2003, it is believed that human activities are the main source of aerosols in the eastern part of China. This is based on the facts that all areas with relatively high values are consistent with regions of dense population and fast economic development, such as the North China Plain, the Sichuan Basin and the Pearl River Delta. It is also supported by the distribution of 舗gstr鰉 exponents showing that most aerosols in the eastern part of China are closely related to human activities, excepting the strong sandstorm episodes occurring in spring, fall and winter. In contrast to developed countries, the 舗gstr鰉 exponent of urban area in China is lower than its surroundings, indicating that the contribution of local floating dust and soot attributed to human activities is significant. Results presented in this paper provide important data for further research on climatic change and environmental study.
文摘分析了MODIS C006 3 km卫星遥感气溶胶产品的算法流程,并与AERONET观测数据进行对比验证,综合新疆阿克苏地区地面空气子站1年的颗粒物质量浓度(PM10)、环境气象资料(能见度、湿度等),评估了该高分辨率气溶胶产品的精度和稳定性.分析表明,MODIS 3 km AOD与AERONET地基AOD(Issyk-Kul)的相关系数(r)达到0.8836,满足期望误差要求,但存在高估;研究区AOD和PM10存在同步变化趋势,新疆阿克苏市区2个空气子站PM10质量浓度与AOD的相关系数(r)均大于0.55,直接对比的相关性好于类似研究;经高度订正和湿度订正后AOD-PM10的相关系数和拟合优度均有所提高,标准误差和变异系数均下降,但提升并不明显.这一相关性结果与研究区本底气象环境条件有关.MODIS 3 km AOD的季平均结果表明,阿克苏地区AOD存在显著的季节性变化,春季明显高于其他季节,主要城市春季平均AOD在1.5以上,夏季和秋季AOD均值基本介于0.6~0.7之间,阿克苏市主城区夏秋季AOD季均值仍在1.0以上,反映人口集聚、城市交通工业发展等大气人为污染的增加导致AOD的增高.结果表明,MODIS C006 3 km AOD产品质量稳定,其月、季平均等长时间尺度结果有更好的空间覆盖,可满足区域环境空气质量评估的需要.
