Aerosol optical properties observed by combined Raman‐elastic backscatter lidar in winter 2009 in Pearl River Delta, south China

Chen, Zhenyi; Liu, Wenqing; Heese, Birgit; Althausen, Dietrich; Baars, Holger; Cheng, Tianhai; Shu, Xiaowen

doi:10.1002/2013jd020200

Cited by 18 publications

(15 citation statements)

References 46 publications

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“…This is consistent with previous measurements that elevated aerosol layers accounted for one-third of the total aerosol layers in the spring, summer, and autumn via a depolarization-sensitive micropulse lidar (MPL) [59]. Dense local aerosols from emissions from the combustion of carbonaceous fuels for heating, combined with low wind speed and frequent static wind due to weaker East Asia winter monsoons, would led to the agglomeration of a large percentage of aerosols in near-surface layers during the winter in Shanghai [60,61]. This is consistent with previous observations that larger proportions of near-surface aerosols against the total column aerosols were observed via MPL in winter [59].…”

Section: The Recommended Vertical Correction Schemesmentioning

confidence: 99%

Impact and Suggestion of Column-to-Surface Vertical Correction Scheme on the Relationship between Satellite AOD and Ground-Level PM2.5 in China

et al. 2017

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As China is suffering from severe fine particle pollution from dense industrialization and urbanization, satellite-derived aerosol optical depth (AOD) has been widely used for estimating particulate matter with an aerodynamic diameter less than 2.5 µm (PM 2.5 ). However, the correlation between satellite AOD and ground-level PM 2.5 could be influenced by aerosol vertical distribution, as satellite AOD represents the entire column, rather than just ground-level concentration. Here, a new column-to-surface vertical correction scheme is proposed to improve separation of the near-surface and elevated aerosol layers, based on the ratio of the integrated extinction coefficient within 200-500 m above ground level (AGL), using the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP)) aerosol profile products. There are distinct differences in climate, meteorology, terrain, and aerosol transmission throughout China, so comparisons between vertical correction via CALIOP ratio and planetary boundary layer height (PBLH) were conducted in different regions from 2014 to 2015, combined with the original Pearson coefficient between satellite AOD and ground-level PM 2.5 for reference. Furthermore, the best vertical correction scheme was suggested for different regions to achieve optimal correlation with PM 2.5 , based on the analysis and discussion of regional and seasonal characteristics of aerosol vertical distribution. According to our results and discussions, vertical correction via PBLH is recommended in northwestern China, where the PBLH varies dramatically, stretching or compressing the surface aerosol layer; vertical correction via the CALIOP ratio is recommended in northeastern China, southwestern China, Central China (excluding summer), North China Plain (excluding Beijing), and the spring in the southeast coast, areas that are susceptible to exogenous aerosols and exhibit the elevated aerosol layer; and original AOD without vertical correction is recommended in Beijing and the southeast coast (excluding spring), where the elevated aerosol layer rarely occurs and a large proportion of aerosol is aggregated in near-surface. Moreover, validation experiments in 2016 agreed well with our discussions and conclusions drawn from the experiments of the first two years. Furthermore, suggested vertical correction scheme was applied into linear mixed effect (LME) model, and high cross validation (CV) R 2 (~85%) and relatively low root mean square errors (RMSE,~20 µg/m 3 ) were achieved, which demonstrated that the PM 2.5 estimation agreed well with the measurements. When compared to the original situation, CV R 2 values and RMSE after vertical correction both presented improvement to a certain extent, proving that the suggested vertical correction schemes could further improve the estimation accuracy of PM 2.5 based on sophisticated model in China. Estimating PM 2.5 with better accuracy could contribute to a more

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Section: The Recommended Vertical Correction Schemesmentioning

confidence: 99%

Impact and Suggestion of Column-to-Surface Vertical Correction Scheme on the Relationship between Satellite AOD and Ground-Level PM2.5 in China

et al. 2017

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“…Concurrently, ground-based data of aerosol properties were collected in the city of Zhongshan with two sun photometers (Cimel CE318-2 and Schulz SP1A) and a LIDAR (Chen et al, 2014). From these data the single scattering albedo ω and asymmetry parameter g of the aerosol particles were retrieved by the inversion method described by Dubovik and King (2000).…”

Section: Field Campaign In Zhongshan Pearl River Delta Chinamentioning

confidence: 99%

“…The vertical aerosol extinction profile b ext (z) was measured with a combined Raman (387 nm), elastic (355 and 532 nm) backscatter LIDAR. An overview of the applied airborne and ground-based instruments and measurement uncertainties are given in Table 1 ( Andrews et al, 2006;Chen et al, 2014).…”

Section: Field Campaign In Zhongshan Pearl River Delta Chinamentioning

confidence: 99%

Adaption of the MODIS aerosol retrieval algorithm using airborne spectral surface reflectance measurements over urban areas: a case study

Jäkel

Mey

Levy³

et al. 2015

Atmos. Meas. Tech.

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Abstract. MODIS (MOderate-resolution Imaging Spectroradiometer) retrievals of aerosol optical depth (AOD) are biased over urban areas, primarily because the reflectance characteristics of urban surfaces are different than that assumed by the retrieval algorithm. Specifically, the operational "darktarget" retrieval is tuned towards vegetated (dark) surfaces and assumes a spectral relationship to estimate the surface reflectance in blue and red wavelengths. From airborne measurements of surface reflectance over the city of Zhongshan, China, were collected that could replace the assumptions within the MODIS retrieval algorithm. The subsequent impact was tested upon two versions of the operational algorithm, Collections 5 and 6 (C5 and C6). AOD retrieval results of the operational and modified algorithms were compared for a specific case study over Zhongshan to show minor differences between them all. However, the Zhongshanbased spectral surface relationship was applied to a much larger urban sample, specifically to the MODIS data taken over Beijing between 2010 and 2014. These results were compared directly to ground-based AERONET (AErosol RObotic NETwork) measurements of AOD. A significant reduction of the differences between the AOD retrieved by the modified algorithms and AERONET was found, whereby the mean difference decreased from 0.27 ± 0.14 for the operational C5 and 0.19±0.12 for the operational C6 to 0.10±0.15 and −0.02 ± 0.17 by using the modified C5 and C6 retrievals. Since the modified algorithms assume a higher contribution by the surface to the total measured reflectance from MODIS, consequently the overestimation of AOD by the operational methods is reduced. Furthermore, the sensitivity of the MODIS AOD retrieval with respect to different surface types was investigated. Radiative transfer simulations were performed to model reflectances at top of atmosphere for predefined aerosol properties. The reflectance data were used as input for the retrieval methods. It was shown that the operational MODIS AOD retrieval over land reproduces the AOD reference input of 0.85 for dark surface types (retrieved AOD = 0.87 (C5)). An overestimation of AOD = 0.99 is found for urban surfaces, whereas the modified C5 algorithm shows a good performance with a retrieved value of AOD = 0.86.

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“…During this time, two events of moderate and hazy pollution were observed by the Raman lidar of the Anhui Institute of Optics and Fine Mechanics, CAS, Hefei, China Hefei Optics Institute and a sun photometer from TROPOS [2].…”

Section: Introductionmentioning

confidence: 99%

Aerosol Properties over Southeastern China from Multi-Wavelength Raman and Depolarization Lidar Measurements

Heese

Althausen

Baars

et al. 2016

EPJ Web of Conferences

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A dataset of particle optical properties of highly polluted urban aerosol over the Pearl River Delta, Guangzhou, China is presented. The data were derived from multi-wavelengths Raman and depolarization lidar Polly XT and AERONET sun photometer measurements. The measurement campaign was conducted from Nov 2011 to June 2012. High aerosol optical depth was observed in the polluted atmosphere over this megacity, with a mean value of 0.54 ± 0.33 and a peak value of even 1.9. For the particle characterization the lidar ratio and the linear particle depolarization ratio, both at 532 nm, were used. The mean values of these properties are 48.0 sr ± 10.7 sr for the lidar ratio and 4%+-4% for the particle depolarization ratio, which means most depolarization measurements stayed below 10%. So far, most of these results indicate urban pollution particles mixed with particles arisen from biomass and industrial burning.

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Aerosol optical properties observed by combined Raman‐elastic backscatter lidar in winter 2009 in Pearl River Delta, south China

Cited by 18 publications

References 46 publications

Impact and Suggestion of Column-to-Surface Vertical Correction Scheme on the Relationship between Satellite AOD and Ground-Level PM2.5 in China

Impact and Suggestion of Column-to-Surface Vertical Correction Scheme on the Relationship between Satellite AOD and Ground-Level PM2.5 in China

Adaption of the MODIS aerosol retrieval algorithm using airborne spectral surface reflectance measurements over urban areas: a case study

Aerosol Properties over Southeastern China from Multi-Wavelength Raman and Depolarization Lidar Measurements

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