Observations of relative humidity effects on aerosol light scattering in the Yangtze River Delta of China

Zhang, L.; Sun, Junying; Shen, Xiaojing; Zhang, Y. M.; Che, Huizheng; L., Q.; Zhang, Y. W.; Zhang, X. Y.; Ogren, J. A.

doi:10.5194/acp-15-8439-2015

Cited by 108 publications

(79 citation statements)

References 69 publications

(83 reference statements)

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“…Precipitation obviously affects the AOD due to wash out of the aerosol particles, although on warm days with high relative humidity the aerosol particles swell and small (<100 nm) aerosol particles grow into the optically active size range. As a result, the particle size distribution shifts to larger particles and the aerosol scattering and associated AOD increase (Bian et al, 2014;Zhang et al, 2015). In region 10, in the northeast of China, which has a cooler climate that the EASM does not reach, the AOD maximum occurs in spring.…”

Section: Seasonal Variation By Region For the 2000-2011 Periodmentioning

confidence: 99%

Spatial and seasonal variations of aerosols over China from two decades of multi-satellite observations – Part 1: ATSR (1995–2011) and MODIS C6.1 (2000–2017)

et al. 2018

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Abstract. Aerosol optical depth (AOD) patterns and interannual and seasonal variations over China are discussed based on the AOD retrieved from the Along-Track Scanning Radiometer (ATSR-2, 1995(ATSR-2, -2002, the Advanced ATSR (AATSR, 2002(AATSR, -2012) (together ATSR) and the MODerate resolution Imaging Spectroradiometer (MODIS) aboard the Terra satellite (2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016)(2017). The AOD products used were the ATSR Dual View (ADV) v2.31 AOD and the MODIS/Terra Collection 6.1 (C6.1) merged dark target (DT) and deep blue (DB) AOD product. Together these datasets provide an AOD time series for 23 years, from 1995 to 2017. The difference between the AOD values retrieved from ATSR-2 and AATSR is small, as shown by pixel-by-pixel and monthly aggregate comparisons as well as validation results. This allows for the combination of the ATSR-2 and AATSR AOD time series into one dataset without offset correction.ADV and MODIS AOD validation results show similar high correlations with the Aerosol Robotic Network (AERONET) AOD (0.88 and 0.92, respectively), while the corresponding bias is positive for MODIS (0.06) and negative for ADV ( − 0.07). Validation of the AOD products in similar conditions, when ATSR and MODIS/Terra overpasses are within 90 min of each other and when both ADV and MODIS retrieve AOD around AERONET locations, show that ADV performs better than MODIS in autumn, while MODIS performs slightly better in spring and summer. In winter, both ADV and MODIS underestimate the AERONET AOD.Similar AOD patterns are observed by ADV and MODIS in annual and seasonal aggregates as well as in time series. ADV-MODIS difference maps show that MODIS AOD is generally higher than that from ADV. Both ADV and MODIS show similar seasonal AOD behavior. The AOD maxima shift from spring in the south to summer along the eastern coast further north.The agreement between sensors regarding year-to-year AOD changes is quite good. between ATSR and MODIS with regards to the AOD tendencies in the overlapping period is rather strong in summer, autumn and overall for the yearly average; however, in winter and spring, when there is a difference in coverage between the two instruments, the agreement between ATSR and MODIS is lower.AOD tendencies in China during the 1995-2017 period will be discussed in more detail in Part 2 (a following paper: Sogacheva et al., 2018), where a method to combine AOD time series from ADV and MODIS is introduced, and combined AOD time series are analyzed.

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Section: Seasonal Variation By Region For the 2000-2011 Periodmentioning

confidence: 99%

Spatial and seasonal variations of aerosols over China from two decades of multi-satellite observations – Part 1: ATSR (1995–2011) and MODIS C6.1 (2000–2017)

et al. 2018

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“…That is, hygroscopic effects and/or cloud processing of fine-mode aerosol particles caused greater extinction in June and September compared with July and August. Zhang et al (2015) reported that the hygroscopic particles under high relative humidity conditions could cause strong aerosol light scattering in the Yangtze River Delta. Other meteorological factors also may have played a role in the variations in AOD 440 nm during summer because in July and August, subtropical high-pressure systems prevail, and the planetary boundary layer (PBLH) at Hangzhou is deep, ∼ 1.5-2.0 km (Sun et al, 2017).…”

Section: Aerosol Optical Properties: Aod and Eaementioning

confidence: 99%

Aerosol optical properties and direct radiative forcing based on measurements from the China Aerosol Remote Sensing Network (CARSNET) in eastern China

et al. 2018

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Abstract. Aerosol pollution in eastern China is an unfortunate consequence of the region's rapid economic and industrial growth. Here, sun photometer measurements from seven sites in the Yangtze River Delta (YRD) from 2011 to 2015 were used to characterize the climatology of aerosol microphysical and optical properties, calculate direct aerosol radiative forcing (DARF) and classify the aerosols based on size and absorption. Bimodal size distributions were found throughout the year, but larger volumes and effective radii of fine-mode particles occurred in June and September due to hygroscopic growth and/or cloud processing. Increases in the fine-mode particles in June and September caused AOD 440 nm > 1.00 at most sites, and annual mean AOD 440 nm values of 0.71-0.76 were found at the urban sites and 0.68 at the rural site. Unlike northern China, the AOD 440 nm was lower in July and August (∼ 0.40-0.60) than in January and February (0.71-0.89) due to particle dispersion associated with subtropical anticyclones in summer. Low volumes and large bandwidths of both fine-mode and coarsemode aerosol size distributions occurred in July and August because of biomass burning. Single-scattering albedos at 440 nm (SSA 440 nm ) from 0.91 to 0.94 indicated particles with relatively strong to moderate absorption. Strongly absorbing particles from biomass burning with a significant SSA wavelength dependence were found in July and August at most sites, while coarse particles in March to May were Published by Copernicus Publications on behalf of the European Geosciences Union. 406H. Che et al.: Aerosol optical properties and direct radiative forcing mineral dust. Absorbing aerosols were distributed more or less homogeneously throughout the region with absorption aerosol optical depths at 440 nm ∼ 0.04-0.06, but inter-site differences in the absorption Angström exponent indicate a degree of spatial heterogeneity in particle composition. The annual mean DARF was −93 ± 44 to −79 ± 39 W m −2 at the Earth's surface and ∼ −40 W m −2 at the top of the atmosphere (for the solar zenith angle range of 50 to 80 • ) under cloud-free conditions. The fine mode composed a major contribution of the absorbing particles in the classification scheme based on SSA, fine-mode fraction and extinction Angström exponent. This study contributes to our understanding of aerosols and regional climate/air quality, and the results will be useful for validating satellite retrievals and for improving climate models and remote sensing algorithms.

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“…High hygroscopicity of aerosol 17 particles enhances their ability to scatter light. We examined acidity by comparing the measured 18 mass concentration and the amount needed to fully neutralize sulfate, nitrate, and 19 chloride ions ( ) (Sun et al, 2009;Zhang et al, 2015;Lv et al, 2017): The acidity of aerosol particles can be measured by the parameter acid value (AV) (Zhang …”

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confidence: 99%

Aerosol hygroscopic growth, contributing factors and impact on haze events in a severely polluted region in northern China

Li¹,

Lv²,

Wang³

et al. 2018

Preprint

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Abstract:1 The hygroscopic growth of aerosol particles is a key factor of air pollution because it 2 can significantly reduce visibility. In order to better understand the impact of the 3 hygroscopic growth effect on haze events and contributing factors, we made use of rich 4 measurements during an intensive field campaign conducted in Xingtai, Hebei province 5 of China that has suffered from the most serious pollution in the Northern China Plain. 6Key measurements are from Raman lidar and ground-based instruments such as a 7GrayWolf 6-channel handheld particle/mass meter for atmospheric particulate matter 8 that have diameters less than 1 µm and 2.5 µm (PM1 and PM2.5, respectively), aerosol The aerosol acidity value of Case II (1.50) was greater than that of Case I (1.35) due to

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Observations of relative humidity effects on aerosol light scattering in the Yangtze River Delta of China

Cited by 108 publications

References 69 publications

Spatial and seasonal variations of aerosols over China from two decades of multi-satellite observations – Part 1: ATSR (1995–2011) and MODIS C6.1 (2000–2017)

Spatial and seasonal variations of aerosols over China from two decades of multi-satellite observations – Part 1: ATSR (1995–2011) and MODIS C6.1 (2000–2017)

Aerosol optical properties and direct radiative forcing based on measurements from the China Aerosol Remote Sensing Network (CARSNET) in eastern China

Aerosol hygroscopic growth, contributing factors and impact on haze events in a severely polluted region in northern China

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