scholarly journals Multi-dimensional satellite observations of aerosol properties and aerosol types over three major urban clusters in eastern China

2021 ◽  
Vol 21 (16) ◽  
pp. 12331-12358
Author(s):  
Yuqin Liu ◽  
Tao Lin ◽  
Juan Hong ◽  
Yonghong Wang ◽  
Lamei Shi ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Meteorological Conditions ◽  
River Delta ◽  
Frequency Of Occurrence ◽  
Smoke Aerosol ◽  
The Yrd ◽  
The Vertical Distribution ◽  
Aerosol Types ◽  
Aerosol Properties ◽  
Aerosol Type

Abstract. Using 14 years (2007–2020) of data from passive (MODIS/Aqua) and active (CALIOP/CALIPSO) satellite measurements over China, we investigate (1) the temporal and spatial variation of aerosol properties over the Beijing–Tianjin–Hebei (BTH) region, the Yangtze River Delta (YRD), and the Pearl River Delta (PRD) and (2) the vertical distribution of aerosol types and extinction coefficients for different aerosol optical depth (AOD) and meteorological conditions. The results show the different spatial patterns and seasonal variations of the AOD over the three regions. Annual time series reveal the occurrence of AOD maxima in 2011 over the YRD and in 2012 over the BTH and PRD; thereafter the AOD decreases steadily. Using the CALIOP vertical feature mask, the relative frequency of occurrence (rFO) of each aerosol type in the atmospheric column is analyzed: rFOs of dust and polluted dust decrease from north to south; rFOs of clean ocean, polluted continental, clean continental and elevated smoke aerosol increase from north to south. In the vertical, the peak frequency of occurrence (FO) for each aerosol type depends on region and season and varies with AOD and meteorological conditions. In general, three distinct altitude ranges are observed with the peak FO at the surface (clean continental and clean marine aerosol), at ∼1 km (polluted dust and polluted continental aerosol) and at ∼3 km (elevated smoke aerosol), whereas dust aerosol may occur over the whole altitude range considered in this study (from the surface up to 8 km). The designation of the aerosol type in different height ranges may to some extent reflect the CALIOP aerosol type classification approach. Air mass trajectories indicate the different source regions for the three study areas and for the three different altitude ranges over each area. In this study nighttime CALIOP profiles are used. The comparison with daytime profiles shows substantial differences in the FO profiles with altitude, which suggest effects of boundary layer dynamics and aerosol transport on the vertical distribution of aerosol types, although differences due to day–night CALIOP performance cannot be ruled out.

scholarly journals Multi-dimensional satellite observations of aerosol properties and aerosol types over three major urban clusters in eastern China

2021 ◽  
Author(s):  
Yuqin Liu ◽  
Tao Lin ◽  
Juan Hong ◽  
Yonghong Wang ◽  
Lamei Shi ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Eastern China ◽  
Peak Frequency ◽  
Meteorological Conditions ◽  
River Delta ◽  
Smoke Aerosol ◽  
The Yrd ◽  
The Vertical Distribution ◽  
Aerosol Types ◽  
Aerosol Properties

Abstract. Using nine years (2007–2015) of data from passive (MODIS/Aqua) and active (CALIOP/CALIPSO) satellite measurements over China, we investigate (1) the temporal and spatial variation of aerosol properties over the Beijing-Tianjin-Hebei (BTH) region, the Yangtze River Delta (YRD) and the Pearl River Delta (PRD) and (2) the vertical distribution of aerosol types and extinction coefficients for different aerosol optical depth (AOD) and meteorological conditions. The results show the different spatial patterns and seasonal variations of the AOD over the three regions. Annual time series reveal the occurrence of AOD maxima in 2011 over the YRD and in 2012 over the BTH and PRD; thereafter the AOD decreases steadily. Using the CALIOP vertical feature mask, the contributions of different aerosol types to the AOD were analysed: contributions of dust and polluted dust decrease from north to south, contributions of clean ocean, polluted continental, clean continental and smoke aerosol increase from south to north. In the vertical, the peak frequency of occurrence (FO) for each aerosol type depends on region and season and varies with AOD and meteorological conditions. In general, three distinct layers are observed with the peak FO at the surface (clean continental and clean marine aerosol), at ~1 km (polluted dust and polluted continental aerosol) and at ~3 km (smoke aerosol), whereas dust aerosol may occur all over the altitude range considered in this study (from the surface up to 8 km). In this study nighttime CALIOP profiles were used. The comparison with daytime profiles shows substantial differences in the FO profiles with altitude which suggest effects of boundary layer dynamics and aerosol transport on the vertical distribution of aerosol types.

scholarly journals AN AEROSOL TYPE CLASSIFICATION METHOD BASED ON REMOTE SENSING DATA IN GUANGDONG, CHINA

2019 ◽  
Vol XLII-3/W9 ◽  
pp. 239-243
Author(s):  
Y. C. Zheng ◽  
L. L. Li ◽  
Y. P. Wang
Keyword(s):  
Remote Sensing ◽  
Mahalanobis Distance ◽  
Mixed Type ◽  
Remote Sensing Data ◽  
Classification Method ◽  
Sensing Data ◽  
Aerosol Classification ◽  
Aerosol Types ◽  
Aerosol Properties ◽  
Aerosol Type

Abstract. This paper provides an aerosol classification method based on remote sensing data in Guangdong, China in year 2010 and 2011. Aerosol Optical Depth, Angstrom Exponent and Ultraviolet Aerosol Index, as important properties of aerosols, are introduced into classification. Data of these three aerosol properties are integrated to establish a 3-dimension dataset, and k-means clustering algorithm with Mahalanobis distance is used to find out four clusters of the dataset, which respectively represents four aerosol types of urban-industrial, dust, biomass burning and mixed type. Prior knowledge about the understanding of each aerosol type is involved to associate each cluster with aerosol type. Temporal variation of the aerosol properties shows similarities between these two years. The proportion of aerosol types in different cities of Guangdong Province is also calculated, and result shows that in most cities urban-industrial aerosols takes the largest proportion while the mixed type aerosols takes the second place. Classification results prove that k-means cluster algorithm with Mahalanobis distance is a brief and efficient method for aerosol classification.

scholarly journals Two-way feedback mechanism between unfavorable meteorological conditions and cumulative aerosol pollution exists in various haze regions of China

2018 ◽  
Author(s):  
Junting Zhong ◽  
Xiaoye Zhang ◽  
Yaqiang Wang ◽  
Jizhi Wang ◽  
Xiaojing Shen ◽  
...  
Keyword(s):  
Ground Surface ◽  
Stable Stratification ◽  
Yangtze River Delta ◽  
Reanalysis Data ◽  
Feedback Mechanism ◽  
Meteorological Conditions ◽  
River Delta ◽  
Regional Transport ◽  
Aerosol Pollution ◽  
The Yrd

Abstract. Accompanied by unfavorable meteorological conditions with stable stratification in various haze regions of China, persistent heavy aerosol pollution episodes lasting more than 3 consecutive days (HPEs) frequently occur, particularly in winter. In the North China Plain (NCP), explosive growth in PM2.5, which occurs in some HPES, is dominated by a two-way feedback mechanism between further worsened unfavorable meteorological conditions and cumulative aerosol pollution. However, whether such a two-way feedback mechanism exists in other key haze regions is uncertain; these regions include the Guanzhong Plain (GZP), the Yangtze River Delta (YRD) region, the Two Lakes Basin (TLB), the Pearl River Delta (PRD) region, the Sichuan Basin (SB), and the Northeast China Plain (NeCP). In this study, using surface PM2.5 and radiation observations, radiosonde observations, and reanalysis data, we observed the existence of a two-way feedback mechanism in the above six regions. In the SB, this two-way feedback mechanism is weak due to the suppression of cloudy mid-upper layers. In the more polluted NCP, the FWRP, and the NeCP, the feedback is more striking than that in the YRD, the TLB, and the PRD. In these regions, the feedback of worsened meteorological conditions on PM2.5 explains 60–70 % of the increase in PM2.5 during the cumulative stages (CSs). For each region, the low-level cooling bias becomes increasingly substantial with aggravating aerosol pollution and a closer distance to the ground surface. With PM2.5 mass concentrations greater than 400 μg m−3, the near-ground bias exceeded −4 ºC in Beijing and reached up to approximately −4 ºC in Xi’an; this result was caused by accumulated aerosol mass to some extent. In addition to the increase in PM2.5 caused by the two-way feedback, these regions also suffer from the regional transport of pollutants, including inter-regional transport in the FWRP, trans-regional transport from the NCP to the YRD and the TLB, and southwesterly transport in the NeCP.

scholarly journals Satellite observed indications of aerosol effects on warm cloud properties over Yangtze River Delta of China

2016 ◽  
Author(s):  
Yuqin Liu ◽  
Gerrit de Leeuw ◽  
Veli-Matti Kerminen ◽  
Jiahua Zhang ◽  
Putian Zhou ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Yangtze River ◽  
Yangtze River Delta ◽  
Absorption Efficiency ◽  
Meteorological Conditions ◽  
River Delta ◽  
Smoke Aerosol ◽  
Cloud Properties ◽  
Aerosol Effects ◽  
The Impact

Abstract. Aerosol effects on summertime low warm clouds over the Yangtze River Delta (YRD) are examined using co-located MODIS, CALIOP and CloudSat observations. By taking the vertical locations of aerosol and cloud layers into account, we use simultaneously observed aerosol and cloud data to investigate relationships between cloud properties and the amount of aerosol particles (using aerosol optical depth, AOD, as a proxy). Also, we investigate the impact of aerosol types on the variation of cloud properties with AOD. Finally, we explore how meteorological conditions affect these relationships using ERA Interim Reanalysis data. This study shows that the relation between cloud droplet effective radius (CDR) and AOD depends on the aerosol abundance, with a different behaviour for low and high AOD (i.e. AOD  0.3). Cloud fraction (CF) is found to be little dependent on the AOD when aerosol and cloud physically interact, but has a positive relation in case of well-separated clouds. Cloud optical Thickness (COT) is found to decrease when AOD increases, which may be due to radiative effects and retrieval artefacts caused by absorbing aerosol. Conversely, cloud top pressure (CTP) tends to increase with elevated AOD, indicating that the aerosol is not always prone to expand the vertical extension. Furthermore, separation of cases with either polluted dust or smoke aerosol shows that COT and CF are smaller for clouds mixed with smoke aerosol which is ascribed to the higher absorption efficiency of smoke than dust. The variation of cloud properties with AOD is analysed for different values of relative humidity (RH) and boundary layer thermodynamic and dynamic conditions, showing that high relative humidity and upward motion of air parcels can enhance the strength of aerosol-cloud interaction, especially pronounced in heavily polluted conditions than in moderately polluted conditions. Meteorological conditions play a weak role in the COT-AOD and CTP-AOD relationships throughout the range of AOD. Overall, the interpretation of the observed relationships between cloud properties and AOD requires that ambient environmental conditions are considered in addition to the aerosol and cloud parameters.

scholarly journals Estimating Ground-Level Particulate Matter in Five Regions of China Using Aerosol Optical Depth

2020 ◽  
Vol 12 (5) ◽  
pp. 881
Author(s):  
Qiaolin Zeng ◽  
Jinhua Tao ◽  
Liangfu Chen ◽  
Hao Zhu ◽  
SongYan Zhu ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Yangtze River ◽  
River Delta ◽  
Research Network ◽  
Near Surface ◽  
Type Method ◽  
Aerosol Types ◽  
Aerosol Type

Aerosol optical depth (AOD) has been widely used to estimate near-surface particulate matter (PM). In this study, ground-measured data from the Campaign on Atmospheric Aerosol Research network of China (CARE-China) and the Aerosol Robotic Network (AERONET) were used to evaluate the accuracy of Visible Infrared Imaging Radiometer Suite (VIIRS) AOD data for different aerosol types. These four aerosol types were from dust, smoke, urban, and uncertain and a fifth “type” was included for unclassified (i.e., total) aerosols. The correlation for dust aerosol was the worst (R2 = 0.15), whereas the correlations for smoke and urban types were better (R2 values of 0.69 and 0.55, respectively). The mixed-effects model was used to estimate the PM2.5 concentrations in Beijing–Tianjin–Hebei (BTH), Sichuan–Chongqing (SC), the Pearl River Delta (PRD), the Yangtze River Delta (YRD), and the Middle Yangtze River (MYR) using the classified aerosol type and unclassified aerosol type methods. The results suggest that the cross validation (CV) of different aerosol types has higher correlation coefficients than that of the unclassified aerosol type. For example, the R2 values for dust, smoke, urban, uncertain, and unclassified aerosol types BTH were 0.76, 0.85, 0.82, 0.82, and 0.78, respectively. Compared with the daily PM2.5 concentrations, the air quality levels estimated using the classified aerosol type method were consistent with ground-measured PM2.5, and the relative error was low (most RE was within ±20%). The classified aerosol type method improved the accuracy of the PM2.5 estimation compared to the unclassified method, although there was an overestimation or underestimation in some regions. The seasonal distribution of PM2.5 was analyzed and the PM2.5 concentrations were high during winter, low during summer, and moderate during spring and autumn. Spatially, the higher PM2.5 concentrations were predominantly distributed in areas of human activity and industrial areas.

scholarly journals The two-way feedback mechanism between unfavorable meteorological conditions and cumulative aerosol pollution in various haze regions of China

2019 ◽  
Vol 19 (5) ◽  
pp. 3287-3306 ◽  
Author(s):  
Junting Zhong ◽  
Xiaoye Zhang ◽  
Yaqiang Wang ◽  
Jizhi Wang ◽  
Xiaojing Shen ◽  
...  
Keyword(s):  
Fine Particulate Matter ◽  
Ground Surface ◽  
Reanalysis Data ◽  
Feedback Mechanism ◽  
Meteorological Conditions ◽  
River Delta ◽  
Hunan Province ◽  
Regional Transport ◽  
Aerosol Pollution ◽  
The Yrd

Abstract. Accompanied by unfavorable meteorological conditions with stable stratification in various haze regions of China, persistent heavy aerosol pollution episodes (HPEs) lasting more than 3 consecutive days frequently occur, particularly in winter. In the North China Plain (NCP), explosive growth of fine particulate matter smaller than 2.5 µm in diameter (PM2.5), which occurs during some HPES, is dominated by a two-way feedback mechanism between more unfavorable meteorological conditions and cumulative aerosol pollution. However, the existence of a two-way feedback mechanism such as this in other key haze regions in China is uncertain; these regions include the Guanzhong Plain (GZP), the Yangtze River Delta (YRD) region, the Two Lakes Basin (TLB; a large outflow basin connected to Hubei Province and Hunan Province), the Pearl River Delta (PRD) region, the Sichuan Basin (SB), and the Northeast China Plain (NeCP). In this study, using surface PM2.5 and radiation observations, radiosonde observations, and reanalysis data, we observed the existence of a two-way feedback mechanism in the six abovementioned regions. In the SB, this two-way feedback mechanism is weak due to the suppression of cloudy mid-upper layers. In the more polluted NCP, the GZP, and the NeCP, the feedback is more striking than that in the YRD, the TLB, and the PRD. In these regions, the feedback of worsened meteorological conditions on PM2.5 explains 60 %–70 % of the increase in PM2.5 during the cumulative stages (CSs). For each region, the low-level cooling bias becomes increasingly substantial with increasing aerosol pollution and a closer distance to the ground surface. With PM2.5 mass concentrations greater than 400 µg m−3, the near-ground bias exceeded −4 ∘C in Beijing and reached up to approximately −4 ∘C in Xi'an; this result was caused by accumulated aerosol mass to some extent. In addition to the increase in PM2.5 caused by the two-way feedback, these regions also suffer from the regional transport of pollutants, including inter-regional transport in the GZP, trans-regional transport from the NCP to the YRD and the TLB, and southwesterly transport in the NeCP.

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