Lake Baikal is the biggest reservoir of fresh water with unique flora and fauna;presently it is negatively affected by climate change, water warming, industrial emissions, shipping,touristic activities, and Siberian f...Lake Baikal is the biggest reservoir of fresh water with unique flora and fauna;presently it is negatively affected by climate change, water warming, industrial emissions, shipping,touristic activities, and Siberian forest fires.The assessment of air pollution-related Baikal’s ecosystem damage is an unsolved problem.Ship, based expedition exploring the Baikal atmospheric aerosol loading, was performed over the lake area in July 2018.We combine the aerosol near-water and vertical distributions over the Lake Baikal basin with meteorological observations and air mass transportation simulations.Lidar sounding of aerosol fields in the troposphere assesses the atmospheric background in the pristine areas and the pollution during fire-affected periods.Aerosol optical properties(scattering and spectral absorption) converted to the particle number size, black carbon(BC) mass, and Absorption Angstrom Exponent(AAE) provide the inside into aerosol characterization.Transport of industrial emissions from Krasnoyarsk and Irkutsk regions, and wildfire plumes from Republic of Yakutia relates the pollution sources to the increased concentrations of fine particle numbers, PM_(10) and BC mass over Southern and Northern/Central Baikal, respectively.The highest PM10 and BC are associated to the harbor and touristic areas of intensive shipping and residential biomass burning.Deposition estimates applied to aerosol data exhibit the pollution fluxes to water surface over the whole Baikal area.AAE marks the impact of coal combustion, residential biomass burning, and wildfires indicating the high pollution level of the Lake Baikal ecological system.展开更多
The optical and microphysical properties of aerosols remain one of the greatest uncertainties associated with evaluating the climate forcing attributed to aerosols.Although the trends in aerosol optical depth(AOD)at g...The optical and microphysical properties of aerosols remain one of the greatest uncertainties associated with evaluating the climate forcing attributed to aerosols.Although the trends in aerosol optical depth(AOD)at global and regional scales have been widely examined,little attention has been paid to the trends in type-dependent AODs related to aerosol particle properties.Here,using the aerosol optical component dataset from the Multi-angle Imaging SpectroRadiometer(MISR)instrument,we investigate decadal-scale trends in total aerosol loading as well as AODs for five aerosol components by particle size and morphology during 2003–2018 over land.Relationships between the total AOD(TAOD)trends and type-dependent AOD changes were examined,and the relative contribution of each type-dependent AOD to the overall TAOD trends was quantified.By dividing the TAOD values into four different aerosol pollution levels(APLs)with splits at 0.15,0.40,and 0.80,we further explored the relationships between TAOD changes and interannual variations in the frequency-of-occurrences(FoOs)of these APLs.Long-term trends in FoOs in the different APLs show that there was a significant improvement in air quality between 2003 and 2018 in most land areas,except South Asia,corresponding to a shift from lightly polluted to clean conditions.However,the effects of different APLs on TAOD changes are regionally dependent and their extent of correlation varied spatially.Moreover,we observed that the annual mean TAOD has decreased by 0.47%.a^(-1)over land since 2003(P<0.05).This significant reduction was mainly attributed to the continued reduction in small-sized(<0.7 mm diameter)AOD(SAOD)(-0.74%.a^(-1))and spherical AOD(SPAOD)(-0.46%.a^(-1)).Statistical analysis shows that SAOD and SPAOD respectively accounted for 57.5%and 89.6%of the TAOD,but contributed 82.6%and 90.4%of the trend in TAOD.Our study suggests that small-sized and spherical aerosols composed of sulfate,organic matter,and black carbon play a dominant role in determining interannual variability in land TAOD.展开更多
Numerical simulations are carried out to investigate the effect of cloud condensation nuclei(CCN) concentrations on microphysical processes and precipitation characteristics of hailstorms. Two hailstorm cases are si...Numerical simulations are carried out to investigate the effect of cloud condensation nuclei(CCN) concentrations on microphysical processes and precipitation characteristics of hailstorms. Two hailstorm cases are simulated, a spring case and a summer case, in a semiarid region of northern China, with the Regional Atmospheric Modeling System. The results are used to investigate the differences and similarities of the CCN effects between spring and summer hailstorms. The similarities are:(1) The total hydrometeor mixing ratio decreases, while the total ice-phase mixing ratio enhances, with increasing CCN concentration;(2) Enhancement of the CCN concentration results in the production of a greater amount of small-sized hydrometeor particles, but a lessening of large-sized hydrometeor particles;(3) As the CCN concentration increases, the supercooled cloud water and rainwater make a lesser contribution to hail, while the ice-phase hydrometeors take on active roles in the growth of hail;(4) When the CCN concentration increases, the amount of total precipitation lessens,while the role played by liquid-phase rainfall in the amount of total precipitation reduces, relatively, compared to that of icephase precipitation. The differences between the two storms include:(1) An increase in the CCN concentration tends to reduce pristine ice mixing ratios in the spring case but enhance them in the summer case;(2) Ice-phase hydrometeor particles contribute more to hail growth in the spring case, while liquid water contributes more in the summer case;(3) An increase in the CCN concentration has different effects on surface hail precipitation in different seasons.展开更多
This study analyzes and compares aerosol properties and meteorological conditions during two air pollution episodes in 19–22(E1) and 25–26(E2) December 2016 in Northeast China. The visibility, particulate matter...This study analyzes and compares aerosol properties and meteorological conditions during two air pollution episodes in 19–22(E1) and 25–26(E2) December 2016 in Northeast China. The visibility, particulate matter(PM) mass concentration, and surface meteorological observations were examined, together with the planetary boundary layer(PBL) properties and vertical profiles of aerosol extinction coefficient and volume depolarization ratio that were measured by a ground-based lidar in Shenyang of Liaoning Province, China during December 2016–January 2017.Results suggest that the low PBL height led to poor pollution dilution in E1, while the high PBL accompanied by low visibility in E2 might have been due to cross-regional and vertical air transmission. The PM mass concentration decreased as the PBL height increased in E1 while these two variables were positively correlated in E2. The enhanced winds in E2 diffused the pollutants and contributed largely to the aerosol transport. Strong temperature inversion in E1 resulted in increased PM2.5 and PM10 concentrations, and the winds in E2 favoured the southwesterly transport of aerosols from the North China Plain into the region surrounding Shenyang. The large extinction coefficient was partially attributed to the local pollution under the low PBL with high ground-surface PM mass concentrations in E1,whereas the cross-regional transport of aerosols within a high PBL and the low PM mass concentration near the ground in E2 were associated with severe aerosol extinction at high altitudes. These results may facilitate better understanding of the vertical distribution of aerosol properties during winter pollution events in Northeast China.展开更多
Number concentrations and distributions of 10-10,000 nm particles in a large city (Jinan) in the North China Plain were measured in winter 2009. The mean number concentrations of nucleation mode (10-20 nm), Aitken...Number concentrations and distributions of 10-10,000 nm particles in a large city (Jinan) in the North China Plain were measured in winter 2009. The mean number concentrations of nucleation mode (10-20 nm), Aitken mode (20-100 nm), and accumulation mode (100-1000 nm) particles, as well as total particles were 925, 6898, 2476, and 10,299cm-3, respectively. Two severe haze episodes, with elevated concentrations caused by pollutants accumulating, were observed. Accumulation mode particle concen- trations were significantly higher during the episodes than on clear days, and nucleation mode particle concentrations were pronouncedly higher on clear days than during the episodes. The peaks of domi- nant number, surface area, and mass size distributions were around 30-50, 200-300, and 200-400 rim, respectively, both during the haze episodes and on clear days, but elevated mass and surface area con- centrations around 500-600 nm were also observed during the haze episodes, suggesting these particles had significant contributions to haze formation. These particles were probably formed through larger droplets in cloud and fog evaporating. Two new particle formation events, probably triggered by strong photochemical processes on clear days and significant traffic emissions during haze episode 2, were found. Significant insights were made into haze formation in a oolluted Chinese urban area.展开更多
Daily samples of aerosol(n=27) were collected from September 21 st to October 4th, 2013 in Fukang(44.17°N, 88.45°E, 475 m a.s.l.), Xinjiang, Northwest China. The enrichment factors(EFc) of selected 49 ...Daily samples of aerosol(n=27) were collected from September 21 st to October 4th, 2013 in Fukang(44.17°N, 88.45°E, 475 m a.s.l.), Xinjiang, Northwest China. The enrichment factors(EFc) of selected 49 elements showed that the aerosols had extremely high concentrations of heavy metals, probably indicating their anthropogenic origins. Morphology of individual aerosol particles was determined by scanning electron microscopy and energy-dispersive X-ray microanalysis. Based on morphology and elemental composition, the particles were clustered into three dominant types:(Ⅰ) crustal originated particles: Si/Al-rich particles(36%) and Si/Fe-rich particles(24%);(Ⅱ) mixed source particles; and(Ⅲ) pollution derived particles: Pb-rich particles(10%). The backward trajectories were calculated using the HYSPLIT model, and the results indicated the different anthropogenic sources for heavy metals in Fukang aerosols. Air mass from north was identified as the most polluted source when compared to south and west.展开更多
To understand the contribution of new particle formation(NPF)events to ambient fine particle pollution,measurements of particle size distributions,trace gases and meteorological conditions,were conducted at a suburban...To understand the contribution of new particle formation(NPF)events to ambient fine particle pollution,measurements of particle size distributions,trace gases and meteorological conditions,were conducted at a suburban site(NJU)from October to December 2016 and at an industrial site(NUIST)from September to November 2015 in Nanjing.According to the temporal evolution of the particle size distributions,three types NPF events were observed:typical NPF(Type A),moderate NPF events(Type B)and strong NPF(Type C)events.The favorable conditions for Type A events included low relative humidity,low concentration of pre-existing particles,and high solar radiation.The favorable conditions of Type B events were similar to Type A,except for a higher concentration of pre-existing particles.Type C events were more likely to happen with the higher relative humidity,lower solar radiation and continuous growth of pre-existing particle concentration.The formation rate of 3 nm(J3)was the lowest for Type A events and highest for Type C events.In contrast,the growth rates of 10 nm and 40 nm particles were the highest for Type A,and lowest for Type C.Results show that NPF events with only higher J3 would lead to the accumulation of nucleation mode particles.Sulfuric acid was important for the formation of particles but had little effect on the growth of particle size.展开更多
Visibility observed at different altitudes is favorable to understand the causes of air pol-lution.We conducted 4-years of observations of visibility at 2.8 and 60 m and particulate matter(PM)concentrations from 2015 ...Visibility observed at different altitudes is favorable to understand the causes of air pol-lution.We conducted 4-years of observations of visibility at 2.8 and 60 m and particulate matter(PM)concentrations from 2015 to 2018 in Shenyang,a provincial city in Northeast China.The results indicated that visibility increased with the increasing height in winter(especially at night),and decreased with height in summer(especially at the daytime).PM concentration exhibited opposite vertical variation to visibility,reflecting that visibility de-grades with the increase of aerosol concentration in the air.The radiosonde meteorological data showed that weak turbulence in the planetary boundary layer(PBL)in winter favored aerosols'accumulation near the surface.Whereas in summer,unstable atmospheric con-ditions,upper-level moister environment,and regional transport of air pollutants resulted in the deterioration of upper-level visibility.Inter-annual variation in the two-level visibility indicated that the upper-level visibility improved more significantly than low-level visibil-ity,much likely due to the reduction in emission of elevated point sources in Shenyang.Our study suggested that strengthening the control of surface non-point emissions is a promis-ing control strategy to improve Shenyang air quality.展开更多
基金the financial support of LIN SB RAS state task No.0279-2021-0014performed under the partial support of PEEX programRFBR project № 20-55-12001 for support of aethalometrical measurements and data analyzing。
文摘Lake Baikal is the biggest reservoir of fresh water with unique flora and fauna;presently it is negatively affected by climate change, water warming, industrial emissions, shipping,touristic activities, and Siberian forest fires.The assessment of air pollution-related Baikal’s ecosystem damage is an unsolved problem.Ship, based expedition exploring the Baikal atmospheric aerosol loading, was performed over the lake area in July 2018.We combine the aerosol near-water and vertical distributions over the Lake Baikal basin with meteorological observations and air mass transportation simulations.Lidar sounding of aerosol fields in the troposphere assesses the atmospheric background in the pristine areas and the pollution during fire-affected periods.Aerosol optical properties(scattering and spectral absorption) converted to the particle number size, black carbon(BC) mass, and Absorption Angstrom Exponent(AAE) provide the inside into aerosol characterization.Transport of industrial emissions from Krasnoyarsk and Irkutsk regions, and wildfire plumes from Republic of Yakutia relates the pollution sources to the increased concentrations of fine particle numbers, PM_(10) and BC mass over Southern and Northern/Central Baikal, respectively.The highest PM10 and BC are associated to the harbor and touristic areas of intensive shipping and residential biomass burning.Deposition estimates applied to aerosol data exhibit the pollution fluxes to water surface over the whole Baikal area.AAE marks the impact of coal combustion, residential biomass burning, and wildfires indicating the high pollution level of the Lake Baikal ecological system.
基金supported by the National Key Research and Development Program Pilot Projects of China(2016YFA0601901)the National Science Fund for Distinguished Young Scholars(41825011)the National Natural Science Foundation of China(42030608,41590874,and 41941011)。
文摘The optical and microphysical properties of aerosols remain one of the greatest uncertainties associated with evaluating the climate forcing attributed to aerosols.Although the trends in aerosol optical depth(AOD)at global and regional scales have been widely examined,little attention has been paid to the trends in type-dependent AODs related to aerosol particle properties.Here,using the aerosol optical component dataset from the Multi-angle Imaging SpectroRadiometer(MISR)instrument,we investigate decadal-scale trends in total aerosol loading as well as AODs for five aerosol components by particle size and morphology during 2003–2018 over land.Relationships between the total AOD(TAOD)trends and type-dependent AOD changes were examined,and the relative contribution of each type-dependent AOD to the overall TAOD trends was quantified.By dividing the TAOD values into four different aerosol pollution levels(APLs)with splits at 0.15,0.40,and 0.80,we further explored the relationships between TAOD changes and interannual variations in the frequency-of-occurrences(FoOs)of these APLs.Long-term trends in FoOs in the different APLs show that there was a significant improvement in air quality between 2003 and 2018 in most land areas,except South Asia,corresponding to a shift from lightly polluted to clean conditions.However,the effects of different APLs on TAOD changes are regionally dependent and their extent of correlation varied spatially.Moreover,we observed that the annual mean TAOD has decreased by 0.47%.a^(-1)over land since 2003(P<0.05).This significant reduction was mainly attributed to the continued reduction in small-sized(<0.7 mm diameter)AOD(SAOD)(-0.74%.a^(-1))and spherical AOD(SPAOD)(-0.46%.a^(-1)).Statistical analysis shows that SAOD and SPAOD respectively accounted for 57.5%and 89.6%of the TAOD,but contributed 82.6%and 90.4%of the trend in TAOD.Our study suggests that small-sized and spherical aerosols composed of sulfate,organic matter,and black carbon play a dominant role in determining interannual variability in land TAOD.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41205099 and 41575037)the National Science Foundation of China (Grant No. 41405128)+2 种基金the National Grand Fundamental Research 973 Programs of China (Grant Nos. 2014CB441403 and 2013CB430105)the Special Scientific Research Project of the Meteorological Public Welfare Profession of China (Grant No. GYHY201006031)the Guizhou Province Scientific Research Joint Project (Grant No. G[2013]4001)
文摘Numerical simulations are carried out to investigate the effect of cloud condensation nuclei(CCN) concentrations on microphysical processes and precipitation characteristics of hailstorms. Two hailstorm cases are simulated, a spring case and a summer case, in a semiarid region of northern China, with the Regional Atmospheric Modeling System. The results are used to investigate the differences and similarities of the CCN effects between spring and summer hailstorms. The similarities are:(1) The total hydrometeor mixing ratio decreases, while the total ice-phase mixing ratio enhances, with increasing CCN concentration;(2) Enhancement of the CCN concentration results in the production of a greater amount of small-sized hydrometeor particles, but a lessening of large-sized hydrometeor particles;(3) As the CCN concentration increases, the supercooled cloud water and rainwater make a lesser contribution to hail, while the ice-phase hydrometeors take on active roles in the growth of hail;(4) When the CCN concentration increases, the amount of total precipitation lessens,while the role played by liquid-phase rainfall in the amount of total precipitation reduces, relatively, compared to that of icephase precipitation. The differences between the two storms include:(1) An increase in the CCN concentration tends to reduce pristine ice mixing ratios in the spring case but enhance them in the summer case;(2) Ice-phase hydrometeor particles contribute more to hail growth in the spring case, while liquid water contributes more in the summer case;(3) An increase in the CCN concentration has different effects on surface hail precipitation in different seasons.
基金Supported by the National Key Research and Development Program of China(2016YFC0203304 and 2016YFA0601901)National Natural Science Foundation of China(41605112,41590874,41375153,and 41375146)+2 种基金Chinese Academy of Meteorological Sciences Basic Research Fund(2017Z011,2016Z001,and 2014R17)Climate Change Special Fund of China Meteorological Administration(CCSF201504)Special Project for Doctoral Research of Liaoning Provincial Meteorological Bureau(D201501)
文摘This study analyzes and compares aerosol properties and meteorological conditions during two air pollution episodes in 19–22(E1) and 25–26(E2) December 2016 in Northeast China. The visibility, particulate matter(PM) mass concentration, and surface meteorological observations were examined, together with the planetary boundary layer(PBL) properties and vertical profiles of aerosol extinction coefficient and volume depolarization ratio that were measured by a ground-based lidar in Shenyang of Liaoning Province, China during December 2016–January 2017.Results suggest that the low PBL height led to poor pollution dilution in E1, while the high PBL accompanied by low visibility in E2 might have been due to cross-regional and vertical air transmission. The PM mass concentration decreased as the PBL height increased in E1 while these two variables were positively correlated in E2. The enhanced winds in E2 diffused the pollutants and contributed largely to the aerosol transport. Strong temperature inversion in E1 resulted in increased PM2.5 and PM10 concentrations, and the winds in E2 favoured the southwesterly transport of aerosols from the North China Plain into the region surrounding Shenyang. The large extinction coefficient was partially attributed to the local pollution under the low PBL with high ground-surface PM mass concentrations in E1,whereas the cross-regional transport of aerosols within a high PBL and the low PM mass concentration near the ground in E2 were associated with severe aerosol extinction at high altitudes. These results may facilitate better understanding of the vertical distribution of aerosol properties during winter pollution events in Northeast China.
基金The authors gratefully acknowledge the NOAA Air Resources Laboratory for providing the HYSPLIT transport and dispersion model and access to the READY website (httP:nready.arl.noaa. gov), which were used in this study. The authors also acknowledge support provided by the Shandong Province Natural Science Foun- dation (ZR2010DQ022), the Independent Innovation Foundation of Shandong University (2012TS041), a China Postdoctoral Science Foundation funded project (20060400982), and the Shandong Post~ doctoral Science Innovation Foundation (200601003).
文摘Number concentrations and distributions of 10-10,000 nm particles in a large city (Jinan) in the North China Plain were measured in winter 2009. The mean number concentrations of nucleation mode (10-20 nm), Aitken mode (20-100 nm), and accumulation mode (100-1000 nm) particles, as well as total particles were 925, 6898, 2476, and 10,299cm-3, respectively. Two severe haze episodes, with elevated concentrations caused by pollutants accumulating, were observed. Accumulation mode particle concen- trations were significantly higher during the episodes than on clear days, and nucleation mode particle concentrations were pronouncedly higher on clear days than during the episodes. The peaks of domi- nant number, surface area, and mass size distributions were around 30-50, 200-300, and 200-400 rim, respectively, both during the haze episodes and on clear days, but elevated mass and surface area con- centrations around 500-600 nm were also observed during the haze episodes, suggesting these particles had significant contributions to haze formation. These particles were probably formed through larger droplets in cloud and fog evaporating. Two new particle formation events, probably triggered by strong photochemical processes on clear days and significant traffic emissions during haze episode 2, were found. Significant insights were made into haze formation in a oolluted Chinese urban area.
基金supported by the National Natural Science Foundation of China(Nos.41201065,41121001,41261017,41171057,41161012)the fund for Creative Research Groups of China(No.41121001)+3 种基金the foundation for Excellent Youth Scholars of CAREERI,CAS(No.51Y251B51)the SKLCS Foundation(No.SKLCSZZ-201201-01)the National Basic Research Program of China(Nos.2010CB951003,2010CB951404)the Knowledge Innovation Project of the Chinese Academy of Sciences(No.KZCX2EW-311)
文摘Daily samples of aerosol(n=27) were collected from September 21 st to October 4th, 2013 in Fukang(44.17°N, 88.45°E, 475 m a.s.l.), Xinjiang, Northwest China. The enrichment factors(EFc) of selected 49 elements showed that the aerosols had extremely high concentrations of heavy metals, probably indicating their anthropogenic origins. Morphology of individual aerosol particles was determined by scanning electron microscopy and energy-dispersive X-ray microanalysis. Based on morphology and elemental composition, the particles were clustered into three dominant types:(Ⅰ) crustal originated particles: Si/Al-rich particles(36%) and Si/Fe-rich particles(24%);(Ⅱ) mixed source particles; and(Ⅲ) pollution derived particles: Pb-rich particles(10%). The backward trajectories were calculated using the HYSPLIT model, and the results indicated the different anthropogenic sources for heavy metals in Fukang aerosols. Air mass from north was identified as the most polluted source when compared to south and west.
基金sponsored by the National Natural Science Foundation of China(Nos.41922052 and 42177080)。
文摘To understand the contribution of new particle formation(NPF)events to ambient fine particle pollution,measurements of particle size distributions,trace gases and meteorological conditions,were conducted at a suburban site(NJU)from October to December 2016 and at an industrial site(NUIST)from September to November 2015 in Nanjing.According to the temporal evolution of the particle size distributions,three types NPF events were observed:typical NPF(Type A),moderate NPF events(Type B)and strong NPF(Type C)events.The favorable conditions for Type A events included low relative humidity,low concentration of pre-existing particles,and high solar radiation.The favorable conditions of Type B events were similar to Type A,except for a higher concentration of pre-existing particles.Type C events were more likely to happen with the higher relative humidity,lower solar radiation and continuous growth of pre-existing particle concentration.The formation rate of 3 nm(J3)was the lowest for Type A events and highest for Type C events.In contrast,the growth rates of 10 nm and 40 nm particles were the highest for Type A,and lowest for Type C.Results show that NPF events with only higher J3 would lead to the accumulation of nucleation mode particles.Sulfuric acid was important for the formation of particles but had little effect on the growth of particle size.
基金This work was supported by the National Natural Science Foundation of China(No.41730647)the Natural Science Foundation of Liaoning Province(No.2020-MS-350)+3 种基金the Science&Technology Project of Liaoning Province(No.2019JH8/10300095)the Key Program of Science Foundation of Liaoning Meteorological Office(Nos.201904,D202101)the Basic Research Funds of Central Public Welfare Research Institutes(Nos.2018SYIAEZD4,2020SYIAEZD1)the Open Project of Shangdianzi National Atmosphere Background Station(No.SDZ2020620)
文摘Visibility observed at different altitudes is favorable to understand the causes of air pol-lution.We conducted 4-years of observations of visibility at 2.8 and 60 m and particulate matter(PM)concentrations from 2015 to 2018 in Shenyang,a provincial city in Northeast China.The results indicated that visibility increased with the increasing height in winter(especially at night),and decreased with height in summer(especially at the daytime).PM concentration exhibited opposite vertical variation to visibility,reflecting that visibility de-grades with the increase of aerosol concentration in the air.The radiosonde meteorological data showed that weak turbulence in the planetary boundary layer(PBL)in winter favored aerosols'accumulation near the surface.Whereas in summer,unstable atmospheric con-ditions,upper-level moister environment,and regional transport of air pollutants resulted in the deterioration of upper-level visibility.Inter-annual variation in the two-level visibility indicated that the upper-level visibility improved more significantly than low-level visibil-ity,much likely due to the reduction in emission of elevated point sources in Shenyang.Our study suggested that strengthening the control of surface non-point emissions is a promis-ing control strategy to improve Shenyang air quality.