scholarly journals The measurement of aerosol optical properties at a rural site in Northern China

2008 ◽  
Vol 8 (8) ◽  
pp. 2229-2242 ◽  
Author(s):  
P. Yan ◽  
J. Tang ◽  
J. Huang ◽  
J. T. Mao ◽  
X.J. Zhou ◽  
...  
Keyword(s):  
Optical Properties ◽  
Urban Area ◽  
Northern China ◽  
Entire Period ◽  
Rural Site ◽  
Aerosol Optical Properties ◽  
Absorption Coefficients ◽  
Air Masses ◽  
Scattering Coefficients ◽  
The Mean

Abstract. Atmospheric aerosols constitute one of the largest sources of uncertainty in the estimation of radiative forcing for climate. From April 2003 to January 2005, in situ measurements of aerosol optical properties were conducted at a rural site in Northern China, Shangdianzi Global Atmosphere Watch (GAW) regional station (SDZ), about 150 km from Beijing. Mean values (standard deviation, S.D.) of scattering and absorption coefficients for the entire period are 174.6 Mm−1 (189.1 Mm-1) and 17.5 Mm−1 (13.4 Mm-1), respectively. These values are approximately one third of the reported values for scattering coefficients and one fifth of those for absorption coefficients obtained in the Beijing urban area. The mean single scattering albedo (SSA) for the entire period was estimated as 0.88 (0.05), which is about 0.07 higher than the values reported for the Beijing urban area, and also higher than the values (0.85) used in a reported climate simulation for China and India. Both the absorption and scattering coefficients showed a seasonal cycle with the lowest values in winter, while the highest values occurred in summer for absorption coefficients and in fall for scattering coefficients. The mean SSA values were lowest in spring and highest in winter. The daily variations of aerosol absorption and scattering coefficients were strongly influenced by synoptic changes throughout the observation period. A trajectory cluster analysis was applied to discern the source characteristics of aerosol optical properties for different air masses. The cluster-mean aerosol scattering coefficients, absorption coefficients and SSA were all high when the air masses moved from SW and SE-E directions to the site and aerosols were influenced with heavy pollution from the dense population centers and industrial areas. The cluster-mean SSA for air masses coming from the polluted areas was not only higher than those with trajectories from the "clean" directions, but also higher than the reported values for the regions with high pollution emissions (such as the Beijing urban area). This fact might reflect the substantial secondary aerosol production during transport. The characteristics of aerosol optical properties measured at this rural site suggest significant impacts of human activities on the regional aerosol.

scholarly journals The measurement of aerosol optical properties at a rural site in Northern China

2007 ◽  
Vol 7 (5) ◽  
pp. 13001-13033 ◽  
Author(s):  
P. Yan ◽  
J. Tang ◽  
J. Huang ◽  
J. T. Mao ◽  
X. J. Zhou ◽  
...  
Keyword(s):  
Optical Properties ◽  
Urban Area ◽  
Northern China ◽  
Entire Period ◽  
Rural Site ◽  
Aerosol Optical Properties ◽  
Absorption Coefficients ◽  
Air Masses ◽  
Scattering Coefficients ◽  
The Mean

Abstract. Atmospheric aerosols contribute one of the largest sources of uncertainty in the estimation of climate forcing. During the period from April 2003 to January 2005, in situ measurements of aerosol optical properties were conducted at a rural site in Northern China, Shangdianzi Global Atmosphere Watch (GAW) regional station (SDZ). Based on the daily average data, the means (standard deviation, S.D.) of scattering and absorption coefficients for the entire period were 174.6 Mm−1 (189.1 Mm−1) and 17.5 Mm−1 (13.4 Mm−1), respectively. These values were approximately one third of the reported values for scattering coefficients and one fifth of those for absorption coefficients obtained in the Beijing urban area. The mean single scattering albedo (SSA) for the entire period was 0.88 (0.05), which was about 0.07 higher than the values reported for the Beijing urban area, and also higher than the values (0.85) used in the climate model simulation for China and India. Both the absorption and scattering coefficients showed the lowest values in winter (11.2 Mm−1 and 128.9 Mm−1, respectively), while the highest values appeared in summer for absorption coefficients (22.1 Mm−1) and in fall for scattering coefficients (208.2 Mm−1). The mean SSA were lowest in spring (0.85) and highest in winter (0.90). The daily variations of aerosol absorption and scattering coefficients were strongly influenced by synoptic changes throughout the observation period. A trajectory cluster analysis was applied to discern the source characteristics of aerosol optical properties for different air masses. The cluster mean scattering coefficients, absorption coefficients and SSA were all high when the air masses moved from SW and SE-E directions to the site and aerosols were influenced with heavy pollution from the dense population centers and industrial areas. The cluster mean SSA for air masses coming from the polluted areas was not only higher than those with the trajectories from the "clean" directions, but also higher than the reported values for the regions with high pollution emissions (such as Beijing urban area). This fact might reflect the substantial secondary aerosol production during the transport. The characteristics of aerosol optical properties measured at this rural site suggest the significant impacts of human activities on the regional aerosol.

scholarly journals Over a ten-year record of aerosol optical properties at SMEAR II

2018 ◽  
Author(s):  
Krista Luoma ◽  
Aki Virkkula ◽  
Pasi Aalto ◽  
Tuukka Petäjä ◽  
Markku Kulmala
Keyword(s):  
Optical Properties ◽  
Volume Concentration ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Aerosol Optical Properties ◽  
Absorption Coefficients ◽  
Mean Values ◽  
Aerosol Forcing ◽  
Seasonal And Diurnal Variations ◽  
The Mean

Abstract. The aerosol optical properties (AOPs) of particles smaller than 10 μm (PM10) and 1 μm (PM1) have been measured at SMEAR II since 2006 and 2010, respectively. For the PM10 particles the mean values of the scattering and absorption coefficients, single-scattering albedo, and backscatter fraction at δ = 550 nm, and scattering and absorption Ångström exponents at the wavelength ranges 450–700 nm and 370–950 nm were 15.2 Mm−1, 2.1 Mm−1, 0.86, 0.15, 1.80 and 0.94 respectively. The time series were used to examine the trends and variation in the AOPs. Statistically significant trends were found for example for the PM10 scattering and absorption coefficients, single-scattering albedo, and backscatter fraction, and the slopes of these trends were −0.342 Mm−1, −0.0952 Mm−1, 3.4 ‧ 10−3, and 1.3 ‧ 10−3 per year. The tendency for the extensive AOPs to decrease correlated well with the decrease in aerosol number and volume concentration. The tendency for the singlescattering albedo and backscattering fraction to increase affected to the effective aerosol forcing efficiency, indicating that the dry aerosols were scattering the radiation more effectively back into space. In addition to these trends, we also observed seasonal and diurnal variations and variations between the AOPs of the PM1 and PM10 particles.

scholarly journals Vertical distributions of aerosol optical properties during the spring 2016 ARIAs airborne campaign in the North China Plain

2018 ◽  
Author(s):  
Fei Wang ◽  
Zhanqing Li ◽  
Xinrong Ren ◽  
Qi Jiang ◽  
Hao He ◽  
...  
Keyword(s):  
Optical Properties ◽  
North China Plain ◽  
North China ◽  
Aerosol Optical Properties ◽  
Air Masses ◽  
Scattering Coefficients ◽  
The North ◽  
The North China Plain ◽  
Aerosol Scattering ◽  
Vertical Distributions

Abstract. Vertical distributions of aerosol optical properties derived from measurements made during 11 aircraft flights over the North China Plain (NCP) in May–June 2016 during the Air Chemistry Research In Asia (ARIAs) were analyzed. Aerosol optical data from in situ aircraft measurements shows good correlation with ground-based measurements. The regional variability of aerosol optical profiles such as aerosol scattering and backscattering, absorption, extinction, single scattering albedo (SSA), and the Ångström exponent (α) are for the first time thoroughly characterized over the NCP. The SSA at 550 nm showed a regional mean value of 0.85 ± 0.02 with moderate to strong absorption and the α ranged from 0.49 to 2.53 (median 1.53) indicating both mineral dust and accumulation mode aerosols. Most of the aerosol particles were located in the lowest 2 km of the atmosphere. We describe three typical planetary boundary layer (PBL) scenarios and associated transport pathways as well as the correlation between aerosol scattering coefficients and relative humidity (RH). Aerosol scattering coefficients decreased slowly with height in the clean PBL condition, but decreased sharply above the PBL under polluted conditions, which showed a strong correlation (R2 ≥ 0.78) with ambient RH. Back-trajectory analysis shows that clean air masses generally originated from the distant north-western part of China while most of the polluted air masses were from the heavily polluted interior and coastal areas near the campaign area.

scholarly journals Vertical distributions of aerosol optical properties during the spring 2016 ARIAs airborne campaign in the North China Plain

2018 ◽  
Vol 18 (12) ◽  
pp. 8995-9010 ◽  
Author(s):  
Fei Wang ◽  
Zhanqing Li ◽  
Xinrong Ren ◽  
Qi Jiang ◽  
Hao He ◽  
...  
Keyword(s):  
Optical Properties ◽  
North China Plain ◽  
North China ◽  
Aerosol Optical Properties ◽  
Air Masses ◽  
Scattering Coefficients ◽  
The North ◽  
The North China Plain ◽  
Aerosol Scattering ◽  
Vertical Distributions

Abstract. Vertical distributions of aerosol optical properties derived from measurements made during 11 aircraft flights over the North China Plain (NCP) in May–June 2016 during the Air Chemistry Research In Asia (ARIAs) were analyzed. Aerosol optical data from in situ aircraft measurements show good correlation with ground-based measurements. The regional variability of aerosol optical profiles such as aerosol scattering and backscattering, absorption, extinction, single scattering albedo (SSA), and the Ångström exponent (α) are thoroughly characterized for the first time over the NCP. The SSA at 550 nm showed a regional mean value of 0.85 ± 0.02 with moderate to strong absorption and the α ranged from 0.49 to 2.53 (median 1.53), indicating both mineral dust and accumulation-mode aerosols. Most of the aerosol particles were located in the lowest 2 km of the atmosphere. We describe three typical planetary boundary layer (PBL) scenarios and associated transport pathways as well as the correlation between aerosol scattering coefficients and relative humidity (RH). Aerosol scattering coefficients decreased slowly with height in the clean PBL condition, but decreased sharply above the PBL under polluted conditions, which showed a strong correlation (R2 ≥ 0.78) with ambient RH. Back-trajectory analysis shows that clean air masses generally originated from the distant northwestern part of China, while most of the polluted air masses were from the heavily polluted interior and coastal areas near the campaign region.

scholarly journals Variability of aerosol optical properties in the Western Mediterranean Basin

2011 ◽  
Vol 11 (5) ◽  
pp. 14091-14125
Author(s):  
M. Pandolfi ◽  
M. Cusack ◽  
A. Alastuey ◽  
X. Querol
Keyword(s):  
Optical Properties ◽  
Sea Breeze ◽  
Single Scattering ◽  
Western Mediterranean ◽  
Aerosol Optical Properties ◽  
Air Masses ◽  
Aerosol Absorption ◽  
Western Mediterranean Basin ◽  
Aerosol Scattering ◽  
The Mean

Abstract. Aerosol light scattering, black carbon (BC) and particulate matter (PM) concentrations were measured at Montseny, a regional background site in the Western Mediterranean Basin (WMB) which is part of the European Supersite for Atmospheric Aerosol Research (EUSAAR). Off line analyses of 24 h PM filters collected with Hi-Vol instruments were performed for the determination of the main chemical components of PM. Measurements of BC were used to calculate the light absorption properties of atmospheric particles. Single Scattering Albedo (SSA) at 635 nm was estimated starting from aerosol scattering and absorption measurements, while Ångström exponents were calculated by means of the three wavelengths (450 nm, 525 nm, 635 nm) aerosol light scattering measurements from Nephelometer. Mean scattering and hemispheric backscattering coefficients (@ 635 nm) were 26.8 ± 23.3 Mm−1 and 4.3 ± 2.7 Mm−1, respectively and the mean aerosol absorption coefficient was 2.8 ± 2.2 Mm−1. Mean values of Single Scattering Albedo (SSA) and Ångström exponent (calculated from 450 nm to 635 nm) at MSY were 0.90 ± 0.05 and 1.2 ± 0.6, respectively. A clear relationship was observed between the PM1/PM10 and PM2.5/PM10 ratios as a function of the calculated Ångström exponents. Mass scattering cross sections for fine mass and sulfate at 635 nm were calculated in 2.8 ± 0.5 m2 g−1 and 11.8 ± 2.2 m2 g−1 respectively, while the mean aerosol absorption cross section was estimated around 10.4 ± 2.0 m2 g−1. The variability in aerosol optical properties in the WMB were largely explained by the origin and ageing of air masses over the measurement site. The sea breeze played an important role in transporting pollutants from the developed WMB coastlines towards inland rural areas, changing the optical properties of aerosols. Aerosol scattering and backscattering coefficients increased by around 40 % in the afternoon when the sea breeze was fully developed while the absorption coefficient increased by more than 100 % as a consequence of the increase in BC concentration at MSY observed under sea breeze circulation. The analysis of the Ångström (Å) exponent as a function of the origin the air masses revealed that polluted winter anticyclonic conditions and summer recirculation scenarios typical of the WMB led to an increase of fine particles in the atmosphere (Å = 1.4 ± 0.1) while the aerosol optical properties under Atlantic Advection episodes and Saharan dust outbreaks were clearly dominated by coarser particles (Å = 0.7 ± 0.3).

scholarly journals Variability of aerosol optical properties in the Western Mediterranean Basin

2011 ◽  
Vol 11 (15) ◽  
pp. 8189-8203 ◽  
Author(s):  
M. Pandolfi ◽  
M. Cusack ◽  
A. Alastuey ◽  
X. Querol
Keyword(s):  
Optical Properties ◽  
Cross Section ◽  
Mediterranean Basin ◽  
Sea Breeze ◽  
Western Mediterranean ◽  
Aerosol Optical Properties ◽  
Air Masses ◽  
Aerosol Absorption ◽  
Western Mediterranean Basin ◽  
The Mean

Abstract. Aerosol light scattering, absorption and particulate matter (PM) concentrations were measured at Montseny, a regional background site in the Western Mediterranean Basin (WMB) which is part of the European Supersite for Atmospheric Aerosol Research (EUSAAR). Off line analyses of 24 h PM filters collected with Hi-Vol instruments were performed for the determination of the main chemical components of PM. Mean scattering and hemispheric backscattering coefficients (@ 635 nm) were 26.6±23.2 Mm−1 and 4.3±2.7 Mm−1, respectively and the mean aerosol absorption coefficient (@ 637 nm) was 2.8±2.2 Mm−1. Mean values of Single Scattering Albedo (SSA) and Ångström exponent (å) (calculated from 450 nm to 635 nm) at MSY were 0.90±0.05 and 1.3±0.5 respectively. A clear relationship was observed between the PM1/PM10 and PM2.5/PM10 ratios as a function of the calculated Ångström exponents. Mass scattering cross sections (MSC) for fine mass and sulfate at 635 nm were 2.8±0.5 m2 g−1 and 11.8±2.2 m2 g−1, respectively, while the mean aerosol absorption cross section (MAC) was 10.4±2.0 m2 g−1. The variability in aerosol optical properties in the WMB were largely explained by the origin and ageing of air masses over the measurement site. The MAC values appear dependent of particles aging: similar to the expected absorption cross-section for fresh emissions under Atlantic Advection episodes and higher under aerosol pollution episodes. The analysis of the Ångström exponent as a function of the origin the air masses revealed that polluted winter anticyclonic conditions and summer recirculation scenarios typical of the WMB led to an increase of fine particles in the atmosphere (å = 1.5±0.1) while the aerosol optical properties under Atlantic Advection episodes and Saharan dust outbreaks were clearly dominated by coarser particles (å = 1.0±0.4). The sea breeze played an important role in transporting pollutants from the developed WMB coastlines towards inland rural areas, changing the optical properties of aerosols. Aerosol scattering and backscattering coefficients increased by around 40 % in the afternoon when the sea breeze was fully developed while the absorption coefficient increased by more than 100 % as a consequence of the increase in the equivalent black carbon concentration (EBC) observed at MSY under sea breeze circulation.

Aerosol optical properties affected by a strong dust storm over central and northern China

2010 ◽  
Vol 27 (3) ◽  
pp. 562-574 ◽  
Author(s):  
Jinyuan Xin ◽  
Wupeng Du ◽  
Yuesi Wang ◽  
Qingxian Gao ◽  
Zhanqing Li ◽  
...  
Keyword(s):  
Optical Properties ◽  
Dust Storm ◽  
Northern China ◽  
Aerosol Optical Properties

scholarly journals Time-Resolved Reflectance Spectroscopy Applied to the Nondestructive Monitoring of the Internal Optical Properties in Apples

2001 ◽  
Vol 55 (10) ◽  
pp. 1368-1374 ◽  
Author(s):  
Rinaldo Cubeddu ◽  
Cosimo D'Andrea ◽  
Antonio Pifferi ◽  
Paola Taroni ◽  
Alessandro Torricelli ◽  
...  
Keyword(s):  
Optical Properties ◽  
Industrial Applications ◽  
Nondestructive Monitoring ◽  
Nondestructive Measurement ◽  
Time Resolved ◽  
Mean Values ◽  
Scattering Coefficients ◽  
Scattering Spectra ◽  
The Mean ◽  
Temporal Dispersion

Time-resolved reflectance has been used for the nondestructive measurement of optical properties in apples. The technique is based on the detection of the temporal dispersion of a short laser pulse injected into the probed medium. The time distribution of re-emitted photons interpreted with a solution of the diffusion equation yields the mean values of the absorption and reduced scattering coefficients of the medium. The proposed technique proved useful for the measurement of the absorption and scattering spectra of different varieties of apples, revealing the spectral shape of chlorophyll. No major variations were observed in the experimental data when the fruit was peeled, showing that the optical properties measured were those of the pulp. With this technique the change in chlorophyll absorption during storage and ripening could be followed. Finally, a compact prototype working at few selected wavelengths was designed and constructed, demonstrating potentialities of the technique for industrial applications.

scholarly journals Seasonal cycle and source analyses of aerosol optical properties in a semi-urban environment at Puijo station in Eastern Finland

2012 ◽  
Vol 12 (12) ◽  
pp. 5647-5659 ◽  
Author(s):  
A. Leskinen ◽  
A. Arola ◽  
M. Komppula ◽  
H. Portin ◽  
P. Tiitta ◽  
...  
Keyword(s):  
Optical Properties ◽  
Paper Mill ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Scattering Coefficient ◽  
Traffic Density ◽  
Aerosol Optical Properties ◽  
Absorption Coefficients ◽  
Data Set ◽  
Pollutant Sources

Abstract. We introduce a four-year (in 2006–2010) continuous data set of aerosol optical properties at Puijo in Kuopio, Finland. We study the annual and diurnal variation of the aerosol scattering and absorption coefficients, hemispheric backscattering fraction, scattering Ångström exponent, and single scattering albedo, whose median values over this period were 7.2 Mm−1 (at 550 nm), 1.0 Mm−1 (at 637 nm), 0.15, 1.93 (between 450 and 550 nm), and 0.85, respectively. The scattering coefficient peaked in the spring and autumn, being 2–4 times those in the summer and winter. An exception was the summer of 2010, when the scattering coefficient was elevated to ~300 Mm−1 by plumes from forest fires in Russia. The absorption coefficient peaked in the winter when soot-containing particles derived from biomass burning were present. The higher relative absorption coefficients resulted in lower single scattering albedo in winter. The optical properties varied also with wind direction and time of the day, indicating the effect of the local pollutant sources and the age of the particles. Peak values in the single scattering albedo were observed when the wind blew from a paper mill and from the sector without local pollutant sources. These observations were linked, respectively, to the sulphate-rich aerosol from the paper mill and the oxygenated organics in the aged aerosol, which both are known to increase the scattering characteristics of aerosols. Decreases in the single scattering albedo in the morning and afternoon, distinct in the summertime, were linked to the increased traffic density at these hours. The scattering and absorption coefficients of residential and long-range transported aerosol (two separate cloud events) were found to be decreased by clouds. The effect was stronger for the scattering than absorption, indicating preferential activation of the more hygroscopic aerosol with higher scattering characteristics.

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