scholarly journals An intensive study of aerosol optical properties in Beijing urban area

2009 ◽  
Vol 9 (3) ◽  
pp. 11413-11440
Author(s):  
X. He ◽  
C. Li ◽  
A. K. H. Lau ◽  
Z. Deng ◽  
J. Mao ◽  
...  
Keyword(s):  
Optical Properties ◽  
Strong Dependence ◽  
Single Scattering ◽  
Urban Site ◽  
Aerosol Optical Properties ◽  
Low Speed ◽  
Aerosol Absorption ◽  
Four Seasons ◽  
Early Afternoon ◽  
Aerosol Parameters

Abstract. In order to quantify the aerosol impact on climate, a range of aerosol parameters is required. In this paper, two-year ground-based observations of aerosol optical properties are conducted at an urban site in Beijing of China. Aerosol absorption coefficient (σa) and scattering coefficient (σs), as well as single scattering albedo (ω) are analyzed for characterizing Beijing urban aerosol. Two-year averages (and standard deviations) for σa, σs and ω are 56±49 Mm−1, 288±281 Mm−1 and 0.80±0.09, respectively. Meanwhile, there is a distinct diurnal variation for σa, with its minimum occurs about 14:00 to 15:00 and maximum in the evening. While, σs peaks in late morning and the minimum occurs in the evening. σs in summer is higher than that in winter. ω in summer is higher than that in winter except before 07:00 a.m. and it peaks in the early afternoon. Both σa and σs show strong dependence on local wind in four seasons. When the wind blows from north with low speed (0–4 m/s), both σa and σs are high, while very low with wind speed higher than 4 m/s. When the wind blows from south with low speed (0–4 m/s), σa and σs are intermediate. ω also shows wind dependence to some extent though not as strong as σa and σs.

scholarly journals An intensive study of aerosol optical properties in Beijing urban area

2009 ◽  
Vol 9 (22) ◽  
pp. 8903-8915 ◽  
Author(s):  
X. He ◽  
C. C. Li ◽  
A. K. H. Lau ◽  
Z. Z. Deng ◽  
J. T. Mao ◽  
...  
Keyword(s):  
Optical Properties ◽  
Strong Dependence ◽  
Single Scattering ◽  
Urban Site ◽  
Aerosol Optical Properties ◽  
Low Speed ◽  
Wind Speeds ◽  
The North ◽  
Early Afternoon ◽  
Regional Problem

Abstract. In order to quantify the aerosol impact on climate, a range of aerosol parameters are required. In this paper, two-year of ground-based observations of aerosol optical properties from an urban site in Beijing of China are assessed. The aerosol absorption coefficient (σa), scattering coefficient (σs), as well as single scattering albedo (ω) are analyzed to aid in characterizing Beijing's urban aerosol. Two-year averages (and standard deviations) for σa at 532 nm, σs at 525 nm and ω at 525 nm are 56±49 Mm−1, 288±281 Mm−1 and 0.80±0.09, respectively. Meanwhile, there is a distinct diurnal variation for σa, with its minimum occurring at approximately 14:00 to 15:00 and maximum at midnight. σs peaks in the late morning and the minimum occurs in the evening. σs in summer is higher than that in winter. ω is also higher in summer than that in winter, except before 07:00 a.m., and peaks in the early afternoon. Both σa and σs show strong dependence on local wind in all four seasons. When the wind blows from the north with low speed (0–2 m/s), the values of σa are high, and in contrast, very low with wind speeds higher than 4 m/s. When the wind blows from south with low speed (0–4 m/s), σa is intermediate. The patterns of the wind dependence of σa indicates that σa is mainly dominated by local emissions. σs displays a similar dependence on wind speed and direction to σa, except in summer. In summer, the σs value is highest when wind is from southeast with speed of 0–6 m/s. This indicates that the particle pollution resulting from regional transport is only significant in the summer season. ω also shows wind dependence to some extent though not as strong as σa or σs. Overall, the wind dependence results provide valuable information about the locations of aerosol pollution sources and suggest that the air pollution in summer is a regional problem but in other seasons it is mainly affected by local urban emissions.

scholarly journals Aerosol light-scattering enhancement due to water uptake during the TCAP campaign

2014 ◽  
Vol 14 (13) ◽  
pp. 7031-7043 ◽  
Author(s):  
G. Titos ◽  
A. Jefferson ◽  
P. J. Sheridan ◽  
E. Andrews ◽  
H. Lyamani ◽  
...  
Keyword(s):  
Optical Properties ◽  
Light Scattering ◽  
Climate Models ◽  
Single Scattering ◽  
Mean Value ◽  
Department Of Energy ◽  
Cape Cod ◽  
Hygroscopic Growth ◽  
Aerosol Optical Properties ◽  
Aerosol Parameters

Abstract. Aerosol optical properties were measured by the DOE/ARM (US Department of Energy Atmospheric Radiation Measurements) Program Mobile Facility during the Two-Column Aerosol Project (TCAP) campaign deployed at Cape Cod, Massachusetts, for a 1-year period (from summer 2012 to summer 2013). Measured optical properties included aerosol light-absorption coefficient (σap) at low relative humidity (RH) and aerosol light-scattering coefficient (σsp) at low and at RH values varying from 30 to 85%, approximately. Calculated variables included the single scattering albedo (SSA), the scattering Ångström exponent (SAE) and the scattering enhancement factor (f(RH)). Over the period of measurement, f(RH = 80%) had a mean value of 1.9 ± 0.3 and 1.8 ± 0.4 in the PM10 and PM1 fractions, respectively. Higher f(RH = 80%) values were observed for wind directions from 0 to 180° (marine sector) together with high SSA and low SAE values. The wind sector from 225 to 315° was identified as an anthropogenically influenced sector, and it was characterized by smaller, darker and less hygroscopic aerosols. For the marine sector, f(RH = 80%) was 2.2 compared with a value of 1.8 obtained for the anthropogenically influenced sector. The air-mass backward trajectory analysis agreed well with the wind sector analysis. It shows low cluster to cluster variability except for air masses coming from the Atlantic Ocean that showed higher hygroscopicity. Knowledge of the effect of RH on aerosol optical properties is of great importance for climate forcing calculations and for comparison of in situ measurements with satellite and remote sensing retrievals. In this sense, predictive capability of f(RH) for use in climate models would be enhanced if other aerosol parameters could be used as proxies to estimate hygroscopic growth. Toward this goal, we propose an exponential equation that successfully estimates aerosol hygroscopicity as a function of SSA at Cape Cod. Further work is needed to determine if the equation obtained is valid in other environments.

scholarly journals Physical and optical properties of aerosols over an urban location in Spain: seasonal and diurnal variability

2010 ◽  
Vol 10 (1) ◽  
pp. 239-254 ◽  
Author(s):  
H. Lyamani ◽  
F. J. Olmo ◽  
L. Alados-Arboledas
Keyword(s):  
Boundary Layer ◽  
Optical Properties ◽  
Seasonal Cycle ◽  
Large Fraction ◽  
Particle Diameter ◽  
Urban Site ◽  
Number Density ◽  
Aerosol Optical Properties ◽  
Scattering Coefficients ◽  
Aerosol Absorption

Abstract. Measurements of aerosol optical properties and aerosol number size distribution obtained during the period from December 2005 to November 2007 at Granada, an urban site in south-eastern Spain, are analyzed. Large variations of the measured variables have been found, and related to variations in emissions sources and meteorological conditions. High values of aerosol absorption and scattering coefficients are obtained during winter and low values are measured during summer. This seasonal pattern in the surface aerosol optical properties is opposite to the seasonal cycle showed by columnar aerosol optical depth. The differences in the seasonal features of the surface and column-integrated data are related to seasonal variations in the aerosol vertical distribution, aerosol sources and boundary layer height. In winter the number density of "fine" particles (0.5<particle diameter<1 μm) is significantly larger than in summer while the number density of "coarse" particles (1<particle diameter<20 μm) is slightly larger during summer and spring than during winter and autumn. The scattering Angström exponent, αs, presents an evident seasonal cycle with values of 1.8±0.2, 1.6±0.3, 1.3±0.3 and 1.4±0.3 in winter, spring, summer and autumn, respectively. This suggests the presence of a large fraction of submicron particles at the site, especially during winter. The aerosols measured in this study contain a large fraction of absorbing material as indicated by the average single-scattering albedo that has values of 0.65±0.07, 0.66±0.06, 0.70±0.06 and 0.73±0.06 in autumn, winter, spring and summer, respectively. The aerosol scattering albedo obtained in the surface boundary layer of Granada is below the critical value of 0.86 that determines the shift from cooling to warming. These results put in evidence the need of efforts to reduce absorbing particles (black carbon) emissions to avoid the possible warming that would result from the reductions of the cooling aerosols only. The aerosol absorption and scattering coefficients present a clear diurnal pattern, in all seasons, with two local maxima, one early in the morning and the second one in the evening. This diurnal cycle is mainly attributed to the diurnal evolution of atmospheric boundary layer and local anthropogenic activities.

scholarly journals Aerosol spectral absorption in the Mexico City area: results from airborne measurements during MILAGRO/INTEX B

2010 ◽  
Vol 10 (13) ◽  
pp. 6333-6343 ◽  
Author(s):  
R. W. Bergstrom ◽  
K. S. Schmidt ◽  
O. Coddington ◽  
P. Pilewskie ◽  
H. Guan ◽  
...  
Keyword(s):  
Optical Properties ◽  
Gulf Of Mexico ◽  
Mexico City ◽  
Optical Depth ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Gas Absorption ◽  
Aerosol Optical Properties ◽  
City Area ◽  
Aerosol Absorption

Abstract. This paper presents estimates of the spectral solar absorption due to atmospheric aerosols during the 2006 MILAGRO/INTEX-B (Megacity Initiative-Local And Global Research Observations/Phase B of the Intercontinental Chemical Transport Experiment) field campaign. The aerosol absorption was derived from measurements of the spectral solar radiation and the spectral aerosol optical depth made on the J31 aircraft flying over the Gulf of Mexico and over Mexico City. We present the spectral single scattering albedo (SSA) and aerosol absorption optical depth (AAOD) for two flights over the Gulf of Mexico and three flights over Mexico City for wavelengths from 350 to approximately 1650 nm. The spectral aerosol optical properties of each case are different and illustrate the variability of the aerosol optical properties in the Mexico City area. The results can be described in terms of three different wavelength regions: The 350–500 nm region where the aerosol absorption often falls off sharply presumably due to organic carbonaceous particles and windblown dust; the 500–1000 nm region where the decrease with wavelength is slower presumably due to black carbon; and the near infrared spectral region (1000 nm to 1650 nm) where it is difficult to obtain reliable results since the aerosol absorption is relatively small and the gas absorption dominates. However, there is an indication of a small and somewhat wavelength independent absorption in the region beyond 1000 nm. For one of the flights over the Gulf of Mexico near the coastline it appears that a cloud/fog formation and evaporation led to an increase of absorption possibly due to a water shell remaining on the particles after the cloud/fog had dissipated. For two of the Mexico City cases, the single scattering albedo is roughly constant between 350–500 nm consistent with other Mexico City results. In three of the cases a single absorption Angstrom exponent (AAE) fits the aerosol absorption optical depth over the entire wavelength range of 350 to 1650 nm relatively well (r2> 0.86).

scholarly journals Physical and optical properties of aerosols over an urban location in Spain: seasonal and diurnal variability

2009 ◽  
Vol 9 (5) ◽  
pp. 18159-18199 ◽  
Author(s):  
H. Lyamani ◽  
F. J. Olmo ◽  
L. Alados-Arboledas
Keyword(s):  
Boundary Layer ◽  
Optical Properties ◽  
Seasonal Cycle ◽  
Large Fraction ◽  
Particle Diameter ◽  
Urban Site ◽  
Number Density ◽  
Aerosol Optical Properties ◽  
Scattering Coefficients ◽  
Aerosol Absorption

Abstract. Measurements of aerosol optical properties and aerosol number size distribution obtained during the period from December 2005 to November 2007 at Granada, an urban site in south-eastern Spain, are analyzed. Large variations of the measured variables have been found, and related to variations in emissions sources and meteorological conditions. High values of aerosol absorption and scattering coefficients are obtained during winter and low values are measured during summer. This seasonal pattern in the surface aerosol optical properties is opposite to the seasonal cycle showed by columnar aerosol optical depth. The differences in the seasonal features of the surface and column-integrated data are related to seasonal variations in the aerosol vertical distribution, aerosol sources and boundary layer height. In winter the number density of fine particles (0.5<particle diameter<1μm) is significantly larger than in summer while the number density of coarse particles (1<particle diameter<20 μm) is slightly larger during summer and spring than during winter and autumn. The scattering Angström exponent, αs, presents an evident seasonal cycle with values of 1.8±0.2, 1.6±0.3, 1.3±0.3 and 1.4±0.3 in winter, spring, summer and autumn, respectively. This suggests the presence of a large fraction of submicron particles at the site, especially during winter. Urban aerosols in Granada contain a large fraction of absorbing material as indicated by the average single-scattering albedo that has values of 0.65±0.07, 0.66±0.06, 0.70±0.06 and 0.73±0.06 in autumn, winter, spring and summer, respectively. The aerosol scattering albedo obtained in the surface boundary layer of Granada is below the critical value of 0.86 that determines the shift from cooling to warming. These results put in evidence the need of efforts to reduce absorbing particles (black carbon) emissions to avoid the possible warming that would result from the reductions of the cooling aerosols only. The aerosol absorption and scattering coefficients present a clear diurnal pattern, in all seasons, with two local maxima, one early in the morning and the second one in the evening. This diurnal cycle is mainly attributed to the diurnal evolution of atmospheric boundary layer and local anthropogenic activities.

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 Aerosol spectral absorption in the Mexico City area: results from airborne measurements during MILAGRO/INTEX B

2009 ◽  
Vol 9 (6) ◽  
pp. 27543-27569 ◽  
Author(s):  
R. W. Bergstrom ◽  
K. S. Schmidt ◽  
O. Coddington ◽  
P. Pilewskie ◽  
H. Guan ◽  
...  
Keyword(s):  
Optical Properties ◽  
Gulf Of Mexico ◽  
Mexico City ◽  
Optical Depth ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Gas Absorption ◽  
Aerosol Optical Properties ◽  
City Area ◽  
Aerosol Absorption

Abstract. This paper presents estimates of the spectral solar absorption due to atmospheric aerosols during the 2006 MILAGRO/INTEX-B (Megacity Initiative-Local And Global Research Observations/Phase B of the Intercontinental Chemical Transport Experiment) field campaign. The aerosol absorption was derived from measurements of the spectral solar radiation and the spectral aerosol optical depth made on the J31 aircraft flying over the Gulf of Mexico and over Mexico City. We present the spectral single scattering albedo (SSA) and aerosol absorption optical depth (AAOD) for two flights over the Gulf of Mexico and three flights over Mexico City for wavelengths from 350 to approximately 1650 nm. The spectral aerosol optical properties of each case are different and illustrate the variability of the aerosol optical properties in the Mexico City area. The results can be described in terms of three different wavelength region: The 350–500 nm region where the aerosol absorption often falls off sharply presumably due to organic carbonaceous particles and windblown dust; the 500–1000 nm region where the decrease with wavelength is slower presumably due to black carbon; and the near infrared spectral region (1000 nm to 1650 nm) where it is difficult to obtain reliable results since the aerosol absorption is relatively small and the gas absorption dominates. However, there is an indication of a small and somewhat wavelength independent absorption in the region beyond 1000 nm. For one of the flights over the Gulf of Mexico near the coastline it appears that a cloud/fog formation and evaporation led to an increase of absorption possibly due to a water shell remaining on the particles after the cloud/fog had dissipated. For two of the Mexico City cases, the single scattering albedo is roughly constant between 350–500 nm consistent with other Mexico City results. In three of the cases a single absorption Angstrom exponent (AAE) fits the aerosol absorption optical depth over the entire wavelength range of 350 to 1650 nm relatively well (r2>0.86).

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.

scholarly journals Evaluating biases in filter-based aerosol absorption measurements using photoacoustic spectroscopy

2019 ◽  
Vol 12 (6) ◽  
pp. 3417-3434 ◽  
Author(s):  
Nicholas W. Davies ◽  
Cathryn Fox ◽  
Kate Szpek ◽  
Michael I. Cotterell ◽  
Jonathan W. Taylor ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Photoacoustic Spectroscopy ◽  
Strong Dependence ◽  
Single Scattering ◽  
Aerosol Absorption ◽  
Aerosol Mass ◽  
Correction Scheme ◽  
Measurement Biases ◽  
Absorption Photometer ◽  
Absorption Measurements

Abstract. Biases in absorption coefficients measured using a filter-based absorption photometer (Tricolor Absorption Photometer, or TAP) at wavelengths of 467, 528 and 652 nm are evaluated by comparing to measurements made using photoacoustic spectroscopy (PAS). We report comparisons for ambient sampling covering a range of aerosol types including urban, fresh biomass burning and aged biomass burning. Data are also used to evaluate the performance of three different TAP correction schemes. We found that photoacoustic and filter-based measurements were well correlated, but filter-based measurements generally overestimated absorption by up to 45 %. Biases varied with wavelength and depended on the correction scheme applied. Optimal agreement to PAS data was achieved by processing the filter-based measurements using the recently developed correction scheme of Müller et al. (2014), which consistently reduced biases to 0 %–18 % at all wavelengths. The biases were found to be a function of the ratio of organic aerosol mass to light-absorbing carbon mass, although applying the Müller et al. (2014) correction scheme to filter-based absorption measurements reduced the biases and the strength of this correlation significantly. Filter-based absorption measurement biases led to aerosol single-scattering albedos that were biased low by values in the range 0.00–0.07 and absorption Ångström exponents (AAEs) that were in error by ± (0.03–0.54). The discrepancy between the filter-based and PAS absorption measurements is lower than reported in some earlier studies and points to a strong dependence of filter-based measurement accuracy on aerosol source type.

scholarly journals Intercomparison of biomass burning aerosol optical properties from in situ and remote-sensing instruments in ORACLES-2016

2019 ◽  
Vol 19 (14) ◽  
pp. 9181-9208 ◽  
Author(s):  
Kristina Pistone ◽  
Jens Redemann ◽  
Sarah Doherty ◽  
Paquita Zuidema ◽  
Sharon Burton ◽  
...  
Keyword(s):  
Optical Properties ◽  
Case Studies ◽  
Biomass Burning ◽  
Radiative Forcing ◽  
Measurement Techniques ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Aerosol Optical Properties ◽  
Biomass Burning Aerosol

Abstract. The total effect of aerosols, both directly and on cloud properties, remains the biggest source of uncertainty in anthropogenic radiative forcing on the climate. Correct characterization of intensive aerosol optical properties, particularly in conditions where absorbing aerosol is present, is a crucial factor in quantifying these effects. The southeast Atlantic Ocean (SEA), with seasonal biomass burning smoke plumes overlying and mixing with a persistent stratocumulus cloud deck, offers an excellent natural laboratory to make the observations necessary to understand the complexities of aerosol–cloud–radiation interactions. The first field deployment of the NASA ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) campaign was conducted in September of 2016 out of Walvis Bay, Namibia. Data collected during ORACLES-2016 are used to derive aerosol properties from an unprecedented number of simultaneous measurement techniques over this region. Here, we present results from six of the eight independent instruments or instrument combinations, all applied to measure or retrieve aerosol absorption and single-scattering albedo. Most but not all of the biomass burning aerosol was located in the free troposphere, in relative humidities typically ranging up to 60 %. We present the single-scattering albedo (SSA), absorbing and total aerosol optical depth (AAOD and AOD), and absorption, scattering, and extinction Ångström exponents (AAE, SAE, and EAE, respectively) for specific case studies looking at near-coincident and near-colocated measurements from multiple instruments, and SSAs for the broader campaign average over the month-long deployment. For the case studies, we find that SSA agrees within the measurement uncertainties between multiple instruments, though, over all cases, there is no strong correlation between values reported by one instrument and another. We also find that agreement between the instruments is more robust at higher aerosol loading (AOD400>0.4). The campaign-wide average and range shows differences in the values measured by each instrument. We find the ORACLES-2016 campaign-average SSA at 500 nm (SSA500) to be between 0.85 and 0.88, depending on the instrument considered (4STAR, AirMSPI, or in situ measurements), with the interquartile ranges for all instruments between 0.83 and 0.89. This is consistent with previous September values reported over the region (between 0.84 and 0.90 for SSA at 550nm). The results suggest that the differences observed in the campaign-average values may be dominated by instrument-specific spatial sampling differences and the natural physical variability in aerosol conditions over the SEA, rather than fundamental methodological differences.

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