scholarly journals Intercomparison between aerosol optical properties by a PREDE skyradiometer and CIMEL sunphotometer over Beijing, China

2008 ◽  
Vol 8 (12) ◽  
pp. 3199-3214 ◽  
Author(s):  
H. Che ◽  
G. Shi ◽  
A. Uchiyama ◽  
A. Yamazaki ◽  
H. Chen ◽  
...  
Keyword(s):  
Optical Properties ◽  
Size Distribution ◽  
Complex Refractive Index ◽  
Weather Conditions ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Aerosol Optical Properties ◽  
Significant Difference ◽  
Beijing China ◽  
Volume Size

Abstract. This study compares the aerosol optical and physical properties simultaneously measured by a SKYNET PREDE skyradiometer and AERONET/PHOTONS CIMEL sunphotometer at a location in Beijing, China. Aerosol optical properties (AOP) including the Aerosol Optical Depth (AOD), Angstrom exponent (α), volume size distribution, single scattering albedo (ω) and the complex refractive index were compared. The difference between the two types of instruments was less than 1.3% for the AOD and less than 4% for the single scattering albedo below the wavelength of 670 nm. There is a difference between the volume size distribution patterns derived from two instruments, which is probably due to difference of measurement protocols and inversion algorithms for the respective instruments. AOP under three distinct weather conditions (background, haze, and dust days) over Beijing were compared by using the retrieved skyradiometer and sunphotometer data combined with MODIS satellite results, pyranometer measurements, PM10 measurements, and backtrajectory analysis. The results show that the significant difference of AOP under background, haze, and dust days over Beijing is probably due to different aerosol components under distinct weather conditions.

scholarly journals Intercomparison between aerosol optical properties by a PREDE skyradiometer and CIMEL sunphotometer over Beijing, China

2007 ◽  
Vol 7 (6) ◽  
pp. 16023-16053 ◽  
Author(s):  
H. Che ◽  
G. Shi ◽  
A. Uchiyama ◽  
A. Yamazaki ◽  
H. Chen ◽  
...  
Keyword(s):  
Optical Properties ◽  
Size Distribution ◽  
Complex Refractive Index ◽  
Weather Conditions ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Aerosol Optical Properties ◽  
Significant Difference ◽  
Beijing China ◽  
Volume Size

Abstract. This study compares the aerosol optical and physical properties simultaneously measured by a SKYNET PREDE skyradiometer and AERONET/PHOTONS CIMEL sunphotometer at a location in Beijing, China. Aerosol optical properties (AOP) including the Aerosol Optical Depth (AOD), Angstrom exponent (α), volume size distribution, single scattering albedo (ω) and the complex refractive index were compared. The difference between the two types of instruments was less than 1.3% for the AOD and less than 4% for the single scattering albedo below the wavelength of 670 nm. There is a difference between the volume size distribution patterns derived from two instruments, which is probablely due to difference of measurement protocols and inversion algorithms for the respective instruments. AOP under three distinct weather conditions (background, haze, and dust days) over Beijing were compared by using the retrieved skyradiometer and sunphotometer data combined with MODIS satellite results, pyranometer measurements, PM10 measurements, and backtrajectory analysis. The results show that the significant difference of AOP under background, haze, and dust days over Beijing is probablely due to different aerosol components under distinct weather conditions.

scholarly journals STUDY OF AEROSOL OPTICAL PROPERTIES OVER TWO SITES IN THE FOOTHILLS OF THE CENTRAL HIMALAYAS

2018 ◽  
Vol XLII-3 ◽  
pp. 1493-1497 ◽  
Author(s):  
D. Rupakheti ◽  
S. Kang ◽  
Z. Cong ◽  
M. Rupakheti ◽  
L. Tripathee ◽  
...  
Keyword(s):  
Optical Properties ◽  
Biomass Burning ◽  
Asymmetry Parameter ◽  
Monsoon Season ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Aerosol Optical Properties ◽  
Central Himalayas ◽  
Aerosol Types ◽  
Volume Size

Atmospheric aerosol possesses impacts on climate system and ecological environments, human health and agricultural productivity. The environment over Himalayas and Tibetan Plateau region are continuously degraded due to the transport of pollution from the foothills of the Himalayas; mostly the Indo-Gangetic Plain (IGP). Thus, analysis of aerosol optical properties over two sites; Lumbini and Kathmandu (the southern slope of central Himalayas) using AERONET’s CIMEL sun photometer were conducted in this study. Aerosol optical depth (AOD at 500 nm), angstrom exponent (α or AE), volume size distribution (VSD), single scattering albedo (SSA) and asymmetry parameter (AP) were studied for 2013–2014 and the average AOD was found to be: 0.64 ± 0.41 (Lumbini) and 0.45 ± 0.30 (Kathmandu). The average AE was found to be: 1.25 ± 0.24 and 1.26 ± 0.18 respectively for two sites. The relation between AOD and AE was used to discriminate the aerosol types over these sites which indicated anthropogenic, mixed and biomass burning origin aerosol constituted the major aerosol types in Lumbini and Kathmandu. A clear bi-modal distribution of aerosol volume size was observed with highest volume concentration during the post-monsoon season in fine mode and pre-monsoon season in coarse mode (Lumbini) and highest value over both modes during pre-monsoon season in Kathmandu. The single scattering albedo (SSA) and asymmetry parameter (AP) analyses suggested aerosols over the Himalayan foothills sites are dominated by absorbing and anthropogenic aerosols from urban and industrial activities and biomass burning. Long-term studies are essential to understand and characterize the nature of aerosol over this research gap zone.

scholarly journals Inter-comparison between the Aerosol Optical Properties Retrieved by Different Inversion Methods from SKYNET Sky Radiometer Observations over Qionghai and Yucheng in China

2019 ◽  
Author(s):  
Zhe Jiang ◽  
Minzheng Duan ◽  
Huizheng Che ◽  
Wenxing Zhang ◽  
Teruyuki Nakajima ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Complex Refractive Index ◽  
Single Scattering ◽  
Inversion Method ◽  
Aerosol Optical Properties ◽  
Validation Data ◽  
Mean Values ◽  
And Inversion ◽  
Volume Size

Abstract. This study analyzed the aerosol optical properties derived by SKYRAD.pack versions 5.0 and 4.2 using the radiometer measurements over Qionghai and Yucheng in China, two new sites of the sky radiometer network (SKYNET). The volume size distribution retrieved by V5.0 presented bimodal patterns with a 0.1–0.2 μm fine particle mode and a 5–6 μm coarse particle mode both over Qionghai and Yucheng. The differences of the volume size distributions between the two versions were very large for the coarse mode with a radius of over 5 μm. The mean values of single scattering albedo (SSA) at 500 nm retrieved from V5.0 were approximately 0.02 lower, but 0.03 higher than those from V4.2 in Qionghai and Yucheng, respectively. The average imaginary part of the complex refractive index (mi) retrieved from V5.0 at all wavelengths was systemically higher than those by V4.2 over Qionghai. Moreover, the differences between the real parts of the complex refractive index (mr) obtained using the two versions were within 4.25 % both at Yucheng and Qionghai. The seasonal variability of the aerosol properties over Qionghai and Yucheng were investigated based on SKYRAD.pack V5.0. The seasonal average SSA during the winter was larger than those in other seasons in Yucheng, while the lowest SSA values occurred in winter over Qionghai. Meanwhile, the mr showed a minimum in winter over both sites. The results can provide validation data in China for SKYNET to continue improving the data-processing and inversion method. The results provide valuable references for continued improvement of the retrieval algorithms of SKYNET and other aerosol observational networks.

scholarly journals Intercomparison between the aerosol optical properties retrieved by different inversion methods from SKYNET sky radiometer observations over Qionghai and Yucheng in China

2020 ◽  
Vol 13 (3) ◽  
pp. 1195-1212 ◽  
Author(s):  
Zhe Jiang ◽  
Minzheng Duan ◽  
Huizheng Che ◽  
Wenxing Zhang ◽  
Teruyuki Nakajima ◽  
...  
Keyword(s):  
Optical Properties ◽  
Size Distribution ◽  
Volume Fraction ◽  
Ground Surface ◽  
Correlation Coefficients ◽  
Single Scattering ◽  
Normal Function ◽  
Aerosol Optical Properties ◽  
Coarse Mode ◽  
Volume Size

Abstract. This study analyzed the aerosol optical properties derived by SKYRAD.pack versions 5.0 and 4.2 (referred to as V5.0 and V4.2) using the radiometer measurements over Qionghai and Yucheng in China, two new sites of the sky radiometer network (SKYNET). As V5.0 uses an a priori size distribution function (SDF) of a bimodal log-normal function, the volume size distribution retrieved by V5.0 presented bimodal patterns with a 0.1–0.2 µm fine particle mode and a 3.0–6.0 µm coarse particle mode both over Qionghai and Yucheng. The differences in the volume size distributions between the two versions were very large for the coarse mode with a radius of over 5 µm. The single scattering albedos (SSAs) by V5.0 correlated with SSAs by V4.2 with R=0.88, 0.87, 0.90, 0.88, and 0.92 at wavelengths of 400, 500, 670, 870, and 1020 nm over Qionghai, respectively. The correlation coefficients were around 0.95, 0.95, 0.96, 0.94, and 0.91 at the five channels in Yucheng. An error of ±5 % for the solid view angle (SVA) introduced about ±2 % differences in retrieved SSA values both by V4.2 and V5.0. An error of ±50 % for ground surface albedo (Ag) caused about 1 % averaged differences in retrieved SSA values by the two versions. With the atmospheric pressure (PRS) increased by 1 %, 2 %, 3 %, and 4 %, the averaged changes in SSAs did not exceed 0.8 % both by V4.2 and V5.0. The SSA differences at 500 nm between the two versions decreased, while aerosol optical depths (AODs) increased over both sites. The seasonal variability of the aerosol properties over Qionghai and Yucheng was investigated based on SKYRAD.pack V5.0. The seasonal averaged AOD over Qionghai had higher values in spring, winter, and autumn and lower values in summer. The AOD averages were commonly higher in summer and spring than in winter and autumn in Yucheng. The lowest seasonal averaged SSAs were both observed in winter at the two sites. The fraction of the fine aerosol particles was much smaller in summer than in other seasons over Qionghai; the volume fraction of the coarse-mode particle in Yucheng had much larger values compared to the fine-mode particle in all seasons. The validation results provide valuable references for continued improvement of the retrieval algorithms of SKYNET and other aerosol observational networks.

scholarly journals Over a 10-year record of aerosol optical properties at SMEAR II

2019 ◽  
Vol 19 (17) ◽  
pp. 11363-11382 ◽  
Author(s):  
Krista Luoma ◽  
Aki Virkkula ◽  
Pasi Aalto ◽  
Tuukka Petäjä ◽  
Markku Kulmala
Keyword(s):  
Optical Properties ◽  
Size Distribution ◽  
Radiative Forcing ◽  
Aerosol Particles ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Aerosol Size Distribution ◽  
Forest Site ◽  
Aerosol Optical Properties ◽  
Absorption Coefficients

Abstract. Aerosol optical properties (AOPs) describe the ability of aerosols to scatter and absorb radiation at different wavelengths. Since aerosol particles interact with the sun's radiation, they impact the climate. Our study focuses on the long-term trends and seasonal variations of different AOPs measured at a rural boreal forest site in northern Europe. To explain the observed variations in the AOPs, we also analyzed changes in the aerosol size distribution. AOPs of particles smaller than 10 µm (PM10) and 1 µm (PM1) have been measured at SMEAR II, in southern Finland, since 2006 and 2010, respectively. For PM10 particles, the median values of the scattering and absorption coefficients, single-scattering albedo, and backscatter fraction at λ=550 nm were 9.8 Mm−1, 1.3 Mm−1, 0.88, and 0.14. The median values of scattering and absorption Ångström exponents at the wavelength ranges 450–700 and 370–950 nm were 1.88 and 0.99, respectively. We found statistically significant trends for the PM10 scattering and absorption coefficients, single-scattering albedo, and backscatter fraction, and the slopes of these trends were −0.32 Mm−1, −0.086 Mm−1, 2.2×10-3, 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 concentrations. The tendency for the backscattering fraction and single-scattering albedo to increase indicates that the aerosol size distribution consists of fewer larger particles and that aerosols absorb less light than at the beginning of the measurements. The trends of the single-scattering albedo and backscattering fraction influenced the aerosol radiative forcing efficiency, indicating that the aerosol particles are scattering the radiation more effectively back into space.

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 Optical properties of atmospheric fine particles near Beijing during the HOPE-J<sup>3</sup>A Campaign

2015 ◽  
Vol 15 (22) ◽  
pp. 33675-33730
Author(s):  
X. Xu ◽  
W. Zhao ◽  
Q. Zhang ◽  
S. Wang ◽  
B. Fang ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Fine Particles ◽  
Complex Refractive Index ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Organic Mass ◽  
Absorption Coefficients ◽  
Aerosol Composition ◽  
Inorganic Species

Abstract. The optical properties and chemical composition of PM1.0 (particulate with an aerodynamic diameter of less than 1.0 μm) particles in a suburban environment (Huairou) near the mega-city Beijing were measured during the HOPE-J3A (Haze Observation Project Especially for Jing-Jin-Ji Area) field campaign. The campaign covered the period November 2014 to January 2015 during the winter coal heating season. The average and standard deviations for the extinction, scattering, absorption coefficients, and the aerosol single scattering albedo (SSA) at λ = 470 nm during the measurement period were 201 ± 240, 164 ± 202, 37 ± 43 Mm-1, and 0.80 ± 0.08, respectively. The mean mass scattering (MSE) and absorption (MAE) efficiencies were 4.77 ± 0.01 and 0.87 ± 0.03 m2g-1, respectively. Highly time-resolved air pollution episodes clearly show the dramatic evolution of the PM1.0 size distribution, extensive optical properties (extinction, scattering, and absorption coefficients) and intensive optical properties (single scattering albedo and complex refractive index) during haze formation, development and decline. Time periods were classified into three different pollution levels (clear, slightly polluted, and polluted) for further analysis. It was found that: (1) The diurnal patterns of the aerosol extinction, scattering, absorption coefficients, and SSA differed for the three pollution classes. (2) The real and imaginary part of complex refractive index (CRI) increased, while the SSA decreased from clear to polluted days. (3) The relative contributions of organic and inorganic species to observed aerosol composition changed significantly from clear to polluted days: the organic mass fraction decreased (50 to 43 %) while the proportion of sulfates, nitrates, and ammonium increased strongly (34 to 44 %). (4) The fractional contribution of chemical components to extinction coefficients was calculated by using the modified IMPROVE algorithm. Organic mass was the largest contributor (58 %) to the total extinction of PM1.0. When the air quality deteriorated, the change of the relative contribution of sulfate aerosol to the total extinction was small, but the contribution of nitrate aerosol increased significantly (from 17 % on clear days to 23 % on polluted days). (5) The observed mass scattering efficiencies increased consistently with the pollution extent, however, the observed mass absorption efficiencies increased consistently with increasing mass concentration in slightly pollution conditions, but decreased under polluted conditions.

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.

scholarly journals Closure on the single scattering albedo in the WRF-Chem framework using data from the MILAGRO campaign

2009 ◽  
Vol 9 (1) ◽  
pp. 5009-5054
Author(s):  
J. C. Barnard ◽  
J. D. Fast ◽  
G. Paredes-Miranda ◽  
W. P. Arnott
Keyword(s):  
Optical Properties ◽  
Black Carbon ◽  
Chemical Properties ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Aerosol Optical Properties ◽  
Mean Values ◽  
Coarse Mode ◽  
Fine Mode ◽  
Using Data

Abstract. Data from the MILAGRO field campaign, which took place in the Mexico City Metropolitan Area (MCMA) during March 2006, is used to perform a closure experiment between aerosol chemical properties and aerosol optical properties. Measured aerosol chemical properties, obtained from the MILAGRO T1 site, are fed to two different "chemical to optical properties" modules. One module uses a sectional approach and is identical to that used in the WRF-Chem model, while the other is based on a modal approach. This modal code is employed as an independent check on the WRF-Chem module. Both modules compute aerosol optical properties and, in particular, the single-scattering albedo, ϖ0, as a function of time. The single-scattering albedos are compared to independent measurements obtained from a photoacoustic spectrometer (PAS). Because chemical measurements of the aerosol coarse mode were not available, and the inlet of the PAS could not ingest aerosols larger than about 2 to 3 μm, we focus here on the fine-mode ϖ0. At 870 nm, the wavelength of the PAS measurements, the agreement between the computed (modal and WRF-Chem) and observed fine-mode ϖ0, averaged over the course of the campaign, is reasonably good. The observed ϖ0 value is 0.77, while for both modules, the calculated value was 0.75 resulting in a difference of 0.02 between observations and both computational approaches. This difference is less than the uncertainty of the observed ϖ0 values (6%, or 0.05), and therefore "closure" is achieved, at least for mean values. After adjusting some properties of black carbon absorption and mass concentration within plausible uncertainty limits, the two modules simulate well the diurnal variation of ϖ0, and the absorption coefficient, Babs, but are less successful in calculating the variation of the scattering coefficient, Bscat. This difficulty is probably caused by the presence of larger particles during the day when windblown dust is ubiquitous; this dust likely increases the proportion of large particles introduced into the PAS. The dust also contributes to a very large aerosol mass loading in the coarse mode, and neglect of the coarse mode may cause significant errors, estimated to be as large as 0.07, in the calculation and measurement of ambient ϖ0. Finally, the observed ϖ0 is compared to the ϖ0 computed by the full WRF-Chem model, which includes prognostic aerosol chemistry. Unlike the results discussed above, a comparison between observed and simulated ϖ0 values reveals major differences. This large discrepancy is probably due, in part, to poor characterization of emissions near the T1 site, particularly black carbon emissions.

Sign in / Sign up

Export Citation Format

Share Document