scholarly journals Influence of biomass burning plumes on HONO chemistry in eastern China

2015 ◽  
Vol 15 (3) ◽  
pp. 1147-1159 ◽  
Author(s):  
W. Nie ◽  
A. J. Ding ◽  
Y. N. Xie ◽  
Z. Xu ◽  
H. Mao ◽  
...  
Keyword(s):  
Surface Area ◽  
Biomass Burning ◽  
Atmospheric Chemistry ◽  
Eastern China ◽  
Yangtze River Delta ◽  
Mean Value ◽  
Air Masses ◽  
Surface Areas ◽  
Agricultural Burning ◽  
Conversion Efficiencies

Abstract. Nitrous acid (HONO) plays a key role in atmospheric chemistry by influencing the budget of hydroxyl radical (OH). In this study, a two-month measurement of HONO and related quantities were analyzed during a biomass burning season in 2012 at a suburban site in the western Yangtze River delta, eastern China. An overall high HONO concentration with the mean value of 0.76 ppbv (0.01 ppbv to 5.95 ppbv) was observed. During biomass burning (BB) periods, both HONO concentration and HONO/NO2 ratio were enhanced significantly (more than a factor of 2, p < 0.01) compared with non-biomass burning (non-BB) periods. A correlation analysis showed that the HONO in BB plumes was more correlated with nitrogen dioxide (NO2) than that with potassium (a tracer of BB). Estimation by the method of potassium tracing suggests a maximum contribution of 17 ± 12% from BB emission to the observed HONO concentrations, and the other over 80% of the observed nighttime HONO concentrations during BB periods were secondarily produced by the heterogeneous conversion of NO2. The NO2-to-HONO conversion rate (CHONO) in BB plumes was almost twice as that in non-BB plumes (0.0062 hr−1 vs. 0.0032 hr−1). Given that the residence time of the BB air masses was lower than that of non-BB air masses, these results suggest BB aerosols have higher NO2 conversion potentials to form HONO than non-BB aerosols. A further analysis based on comparing the surface area at similar particle mass levels and HONO/NO2 ratios at similar surface area levels suggested larger specific surface areas and higher NO2 conversion efficiencies of BB aerosols. A mixed plume of BB and anthropogenic fossil fuel (FF) emissions was observed on 10 June with even higher HONO concentrations and HONO/NO2 ratios. The strong HONO production potential (high HONO/NO2 to PM2.5 ratio) was accompanied with a high sulfate concentration in this plume, suggesting a promotion of mixed aerosols to the HONO formation. In summary, our study suggests an important role of BB in atmospheric chemistry by affecting the HONO budget. This can be especially important in eastern China, where agricultural burning plumes are inevitably mixed with urban and industrial pollution.

scholarly journals Influence of biomass burning plumes on HONO chemistry in eastern China

2014 ◽  
Vol 14 (6) ◽  
pp. 7859-7887 ◽  
Author(s):  
W. Nie ◽  
A. J. Ding ◽  
Y. N. Xie ◽  
Z. Xu ◽  
H. Mao ◽  
...  
Keyword(s):  
Surface Area ◽  
Biomass Burning ◽  
Atmospheric Chemistry ◽  
Eastern China ◽  
Yangtze River Delta ◽  
Mean Value ◽  
Surface Areas ◽  
Agricultural Burning ◽  
Conversion Efficiencies

Abstract. Nitrous acid (HONO) plays a key role in atmospheric chemistry via influencing the budget of hydroxyl radical (OH). In this study, a two-month measurement period of HONO and related quantities were analyzed during a biomass burning season in 2012 at a suburban site in the western Yangtze River delta, eastern China. An overall high HONO concentration with the mean value of 1.1 ppbv was observed. During biomass burning (BB) periods, both HONO concentration and HONO / NO2 ratio were enhanced significantly compared with non-biomass burning periods. A correlation analysis showed that the HONO concentration was not associated potassium (a tracer of BB) in BB plumes, but showed a high correlation with the NO2 concentration, suggesting a principle role of secondary production rather than direct emissions in elevated HONO concentrations. A further analysis based on comparing the surface area at similar PM levels and HONO / NO2 ratios at similar surface area levels suggested larger specific surface areas and higher NO2 conversion efficiencies of BB aerosols. A mixed plume of BB and anthropogenic fossil fuel (FF) emissions was observed on 10 June with even higher HONO concentrations and HONO / NO2 ratios. The strong HONO production potential (high HONO / NO2 to PM2.5 ratio) was accompanied with a high sulfate concentration in this plume, suggesting a promotion of mixed aerosols to HONO formation. In summary, our study suggests an important role of BB in atmospheric oxidation capacity by affecting the HONO budget. This can be especially important in eastern China, where agricultural burning plumes are inevitably mixed with urban pollutions.

scholarly journals Application of SCIAMACHY and MOPITT CO total column measurements to evaluate model results over biomass burning regions and Eastern China

2011 ◽  
Vol 11 (12) ◽  
pp. 6083-6114 ◽  
Author(s):  
C. Liu ◽  
S. Beirle ◽  
T. Butler ◽  
J. Liu ◽  
P. Hoor ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Atmospheric Chemistry ◽  
Eastern China ◽  
Central Africa ◽  
Satellite Observations ◽  
Anthropogenic Sources ◽  
Data Sets ◽  
Vertical Column ◽  
Data Set ◽  
Vertical Column Density

Abstract. We developed a new CO vertical column density product from near IR observations of the SCIAMACHY instrument onboard ENVISAT. For the correction of a temporally and spatially variable offset of the CO vertical column densities we apply a normalisation procedure based on coincident MOPITT (version 4) observations over the oceans. The resulting normalised SCIAMACHY CO data is well suited for the investigation of the CO distribution over continents, where important emission sources are located. We use only SCIAMACHY observations for effective cloud fractions below 20 %. Since the remaining effects of clouds can still be large (up to 100 %), we applied a cloud correction scheme which explicitly considers the cloud fraction, cloud top height and surface albedo of individual observations. The normalisation procedure using MOPITT data and the cloud correction substantially improve the agreement with independent data sets. We compared our new SCIAMACHY CO data set, and also observations from the MOPITT instrument, to the results from three global atmospheric chemistry models (MATCH, EMAC at low and high resolution, and GEOS-Chem); the focus of this comparison is on regions with strong CO emissions (from biomass burning or anthropogenic sources). The comparison indicates that over most of these regions the seasonal cycle is generally captured well but the simulated CO vertical column densities are systematically smaller than those from the satellite observations, in particular with respect to SCIAMACHY observations. Because SCIAMACHY is more sensitive to the lowest part of the atmosphere compared to MOPITT, this indicates that especially close to the surface the model simulations systematically underestimate the true atmospheric CO concentrations, probably caused by an underestimation of CO emissions by current emission inventories. For some biomass burning regions, however, such as Central Africa in July–August, model results are also found to be higher than the satellite observations.

scholarly journals Increasing surface ozone concentrations in the background atmosphere of southern China, 1994–2007

2009 ◽  
Vol 9 (2) ◽  
pp. 10429-10455 ◽  
Author(s):  
T. Wang ◽  
X. L. Wei ◽  
A. J. Ding ◽  
C. N. Poon ◽  
K. S. Lam ◽  
...  
Keyword(s):  
Hong Kong ◽  
Atmospheric Chemistry ◽  
Statistical Significance ◽  
Surface Ozone ◽  
Eastern China ◽  
Positive Trend ◽  
Coastal Regions ◽  
Concentration Data ◽  
Air Masses ◽  
Background Ozone

Abstract. Tropospheric ozone is of great importance with regard to air quality, atmospheric chemistry, and climate change. In this paper we report the first continuous record of surface ozone in the background atmosphere of South China. The data were obtained from 1994 to 2007 at a coastal site in Hong Kong, which is strongly influenced by the outflow of Asian continental air during the winter and the inflow of maritime air from the subtropics in the summer. Overall, the ozone concentration increased by an averaged rate of 0.55 ppbv/yr, with a larger increase in autumn (0.68 ppbv/yr). We also examine the trend in air masses from various source regions in Asia. Using local wind and concurrently measured carbon monoxide (CO) data to filter out local emissions, the mean ozone in air masses from eastern China, using the pooled averaging method, increased by 0.64 ppbv/yr, while ozone levels in other air-mass groups showed a positive trend (0.29–0.67 ppbv/yr) but with lower levels of statistical significance. An examination of the nitrogen dioxide (NO2) column concentration data obtained from GOME and SCIAMACHY reveals an increase in atmospheric NO2 in the three fastest developing coastal regions of China, whereas NO2 in other parts of Asia decreased during the same period. It is believed that the observed increase in background ozone in Hong Kong is primarily due to the increased emissions of NO2 (and possibly volatile organic compounds (VOCs) as well) in the upwind coastal regions of mainland China, which is supported by the observed positive CO trend (5.23 ppbv/yr) at the site. The increase in background ozone contributed two thirds of the annual increase in ''total ozone'' in the downwind urban areas of Hong Kong, suggesting the need to consider distant sources when developing long-term strategies to mitigate local ozone pollution, although short-term strategies should be aimed at sources in Hong Kong and the adjacent Pearl River Delta.

Semi-quantitative understanding of source contribution to nitrous acid (HONO) based on 1 year of continuous observation at the SORPES station in eastern China

2020 ◽  
Author(s):  
Yuliang Liu
Keyword(s):  
Atmospheric Chemistry ◽  
Nitrous Acid ◽  
Heterogeneous Reaction ◽  
Total Concentration ◽  
Eastern China ◽  
Mean Value ◽  
Budget Analysis ◽  
Conversion Frequency ◽  
Yearly Average ◽  
Quantitative Understanding

&lt;p&gt;Nitrous acid (HONO), an important precursor of the hydroxyl radical (OH), has long been recognized as of significance to atmospheric chemistry, but its sources are still debated. In this study, we conducted continuous measurement of HONO from November&amp;#160;2017 to November&amp;#160;2018 at the SORPES station in Nanjing of eastern China. The yearly average mixing ratio of observed HONO was&amp;#160;&lt;span&gt;0.69&amp;#177;0.58&lt;/span&gt;&amp;#8201;ppb, showing a larger contribution to OH relative to ozone with a mean OH production rate of 1.16&amp;#8201;ppb&amp;#8201;h&lt;span&gt;&lt;sup&gt;&amp;#8722;1&lt;/sup&gt;&lt;/span&gt;. To estimate the effect of combustion emissions of HONO, the emitted ratios of HONO to&amp;#160;&lt;span&gt;NO&lt;sub&gt;&lt;em&gt;x&lt;/em&gt;&lt;/sub&gt;&lt;/span&gt;&amp;#160;were derived from 55 fresh plumes (&lt;span&gt;NO&amp;#8725;NO&lt;sub&gt;&lt;em&gt;x&lt;/em&gt;&lt;/sub&gt;&lt;/span&gt;&amp;#8201;&gt;&amp;#8201;0.85), with a mean value of 0.79&amp;#8201;%. During the nighttime, the chemistry of HONO was found to depend on RH, and the heterogeneous reaction of &lt;span&gt;NO&lt;sub&gt;2&lt;/sub&gt;&lt;/span&gt;&amp;#160;on an aerosol surface was presumably responsible for HONO production. The average nighttime&amp;#160;&lt;span&gt;NO&lt;sub&gt;2&lt;/sub&gt;&lt;/span&gt;-to-HONO conversion frequency (&lt;span&gt;&lt;em&gt;C&lt;/em&gt;&lt;sub&gt;HONO&lt;/sub&gt;&lt;/span&gt;) was determined to be&amp;#160;&lt;span&gt;0.0055&amp;#177;0.0032&lt;/span&gt;&amp;#8201;h&lt;span&gt;&lt;sup&gt;&amp;#8722;1&lt;/sup&gt;&lt;/span&gt;&amp;#160;from 137 HONO formation cases. The missing source of HONO around noontime seemed to be photo-induced, with an average&amp;#160;&lt;span&gt;&lt;em&gt;P&lt;/em&gt;&lt;sub&gt;unknown&lt;/sub&gt;&lt;/span&gt;&amp;#160;of 1.04&amp;#8201;ppb&amp;#8201;h&lt;span&gt;&lt;sup&gt;&amp;#8722;1&lt;/sup&gt;&lt;/span&gt;, based on a semi-quantitative HONO budget analysis. An over-determined system of equations was applied to obtain the monthly variations in nocturnal HONO sources. Besides the burning-emitted HONO (accounting for about 23&amp;#8201;% of the total concentration), the contribution of HONO formed heterogeneously on ground surfaces to measured HONO was an approximately constant proportion of 36&amp;#8201;% throughout the year. The soil emission revealed clear seasonal variation and contributed up to 40&amp;#8201;% of observed HONO in July and August. A higher propensity for generating HONO on aerosol surfaces occurred in severe hazes (accounting for 40&amp;#8201;% of the total concentration in January). Our results highlight ever-changing contributions of HONO sources and encourage more long-term observations to evaluate the contributions from varied sources.&lt;/p&gt;

scholarly journals Application of SCIAMACHY and MOPITT CO total column measurements to evaluate model results over biomass burning regions and Eastern China

2011 ◽  
Vol 11 (1) ◽  
pp. 1265-1331 ◽  
Author(s):  
C. Liu ◽  
S. Beirle ◽  
T. Butler ◽  
J. Liu ◽  
P. Hoor ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Atmospheric Chemistry ◽  
Eastern China ◽  
Central Africa ◽  
High Sensitivity ◽  
Satellite Observations ◽  
Anthropogenic Sources ◽  
Vertical Column ◽  
Data Set ◽  
Vertical Column Density

Abstract. We developed a new CO vertical column density product from near IR observations of the SCIAMACHY instrument onboard ENVISAT. For the correction of a temporally and spatially variable offset of the CO vertical column densities we apply a normalisation procedure based on coincident MOPITT (version 4) observations over the oceans. The resulting normalised SCIAMACHY CO data are well suited for the investigation of the CO distribution over continents, where important emission sources are located. We use only SCIAMACHY observations for effective cloud fractions below 20%. Since the remaining effects of clouds can still be large (up to 100%), we applied a cloud correction scheme which explicitly considers the cloud fraction, cloud top height and surface albedo of individual observations. We compared our new SCIAMACHY CO data set, and also observations from the MOPITT instrument, to the results from three global atmospheric chemistry models (MATCH, EMAC at low and high resolution, and GEOS-Chem); the focus of this comparison is on regions with strong CO emissions (from biomass burning or anthropogenic sources). The comparison indicates that over most of these regions the seasonal cycle is generally captured well but the simulated CO vertical column densities are systematically smaller than those from the satellite observations, in particular with respect to SCIAMACHY observations. Because of the high sensitivity of the SCIAMACHY observations to the lowest part of the atmosphere, this indicates that especially close to the surface the model simulations systematically underestimate the true atmospheric CO concentrations, probably caused by an underestimation of CO emissions by current emission inventories. For some biomass burning regions, however, such as Central Africa in July–August, model results are also found to be higher than the satellite observations.

scholarly journals Measurement of Amount of Invaginated Membrane in Mammalian Platelets by Osmotically-Induced Spherocyte Formation

1977 ◽  
Author(s):  
John G. Milton ◽  
M.M. Frojmovic
Keyword(s):  
Surface Area ◽  
Quantitative Estimation ◽  
Platelet Rich Plasma ◽  
Membrane Damage ◽  
Personal Communication ◽  
Dark Field ◽  
Mean Value ◽  
Test Tube ◽  
Lactate Dehydrogenase Activity ◽  
Surface Areas

Invaginated membrane of the surface-connected canalicular system (SCCS) of the resting platelet can be potentially externalized. We have estimated the SCCS surface area by carefully swelling platelets in hypotonic media. Platelets were osmotically stressed by either interfacing a drop of platelet-rich plasma (PRP) with distilled water on a siliconized glass slide or directly in a test tube by careful additions of 60-80% by volume water. Surface areas of the platelets were estimated from a cinematographic analysis of freely rotating platelets. Within five minutes of the addition of water, large smooth spheres (spherocytes) are formed. Soluble, cytoplasmic lactate dehydrogenase activity is not released and visible membrane damage as estimated from dark-field microscopy observations does not occur for at least one hour. The mean value of the spherocyte diameters was 3.9 ± 0.6 um (3 human donors) and did not change over 5 - 60 minutes. It is estimated that the volume of the spherocyte is ~550% greater than that of the original disc and that the surface area has increased by ~300%. Similar results were obtained for rabbit platelets.Since platelet swelling induced osmotically has been shown to yield large spheres with the disappearance of SCCS (J.G. White, personal communication), it is concluded that: 1) the SCCS of the resting platelet can be easily externalized, and 2) osmotic spherocyte formation allows a quantitative estimation of the SCCS surface area.

scholarly journals Aerosol size distribution and new particle formation in the western Yangtze River Delta of China: 2 years of measurements at the SORPES station

2015 ◽  
Vol 15 (21) ◽  
pp. 12445-12464 ◽  
Author(s):  
X. M. Qi ◽  
A. J. Ding ◽  
W. Nie ◽  
T. Petäjä ◽  
V.-M. Kerminen ◽  
...  
Keyword(s):  
Growth Rate ◽  
Yangtze River ◽  
Eastern China ◽  
Formation Rate ◽  
Particle Growth ◽  
Yangtze River Delta ◽  
Particle Formation ◽  
Submicron Particles ◽  
Aerosol Size Distribution ◽  
Air Masses

Abstract. Aerosol particles play important roles in regional air quality and global climate change. In this study, we analyzed 2 years (2011–2013) of measurements of submicron particles (6–800 nm) at a suburban site in the western Yangtze River Delta (YRD) of eastern China. The number concentrations (NCs) of particles in the nucleation, Aitken and accumulation modes were 5300 ± 5500, 8000 ± 4400, 5800 ± 3200 cm−3, respectively. The NCs of total particles are comparable to those at urban/suburban sites in other Chinese megacities, such as Beijing, but about 10 times higher than in the remote western China. Long-range and regional transport largely influenced number concentrations and size distributions of submicron particles. The highest and lowest accumulation-mode particle number concentrations were observed in air masses from the YRD and coastal regions, respectively. Continental air masses from inland brought the highest concentrations of nucleation-mode particles. New particle formation (NPF) events, apparent in 44 % of the effective measurement days, occurred frequently in all the seasons except winter. The frequency of NPF in spring, summer and autumn is much higher than other measurement sites in China. Sulfuric acid was found to be the main driver of NPF events. The particle formation rate was the highest in spring (3.6 ± 2.4 cm−3 s−1), whereas the particle growth rate had the highest values in summer (12.8 ± 4.4 nm h−1). The formation rate was typically high in relatively clean air masses, whereas the growth rate tended to be high in the polluted YRD air masses. The frequency of NPF events and the particle growth rates showed a strong year-to-year difference. In the summer of 2013, associated with a multi-week heat wave and strong photochemical processes, NPF events occurred with larger frequency and higher growth rates compared with the same period in 2012. The difference in the location and strength of the subtropical high pressure system, which influences the air mass transport pathways and solar radiation, seems to be the cause for year-to-year differences. This study reports, up to now, the longest continuous measurement records of submicron particles in eastern China and helps to achieve a comprehensive understanding of the main factors controlling the seasonal and year-to-year variation of the aerosol size distribution and NPF in this region.

Temperature-induced changes in nuclear pore complex frequencies nuclear envelope surface areas and nuclear volumes in light-synchronized Euglena

1981 ◽  
Vol 59 (10) ◽  
pp. 802-809 ◽  
Author(s):  
John S. Greenwood ◽  
John N. A. Lott
Keyword(s):  
Nuclear Envelope ◽  
Surface Area ◽  
Nuclear Pore Complex ◽  
Temperature Shift ◽  
Mean Value ◽  
Nuclear Pore ◽  
Nuclear Surface ◽  
Envelope Surface ◽  
The Third ◽  
Surface Areas

An autotrophic culture of Euglena, synchronized using a day: night (D:N), 14:10-h cycle, was subjected to a 21.5 → 31.5 °C temperature shift and then to a reversed shift in temperature after three D:N cycles at 31.5 °C. Nuclear pore complex (NPC) number per square micrometre and nuclear surface area and volume determinations were made on G1 cells at various intervals. Cells sampled immediately prior to the 21.5 → 31.5 °C shift had a mean value of 37.68 NPC∙μm−2 nuclear envelope surface area, 30.40 NPCs/μm2 after three D:N cycles at.31.5 °C and 39.98 NPCs/μm2 after three D:N cycles at the resumed culture temperature of 21.5 °C. Thus temperature changes affect NPC numbers per square micrometre and these changes are reversible.Mean nuclear surface area was 125.76 μm2 immediately prior to the 21.5 → 31.5 °C shift, and decreased over two D:N cycles at 31.5 °C to 101.30 μm2 by the end of the third D:N cycle. Nuclear envelope surface area, one and two D:N cycles after the 31.5 → 21.5 °C shift, was approximately equal that prior to the 21.5 → 31.5 °C shift. After the third D:N cycle, however, nuclear surface area had increased to 173.05 μm2. The changes in nuclear surface area resulted in large differences in the estimates of the total number of NPCs per nucleus. Euglena immediately prior to the 21.5 → 31.5 °C temperature shift had 4739 NPCs/nucleus; immediately prior to the 31.5 → 21.5 °C shift had 3079 NPCs/nucleus; and had 6919 NPCs/nucleus at 21.5 °C and three D:N cycles after the 31.5 → 21.5 °C shift. Estimates of the number of NPCs per cubic micrometre of nuclear volume were almost identical between these samples.

scholarly journals Semi-quantitative understanding of source contribution to nitrous acid (HONO) based on 1 year of continuous observation at the SORPES station in eastern China

2019 ◽  
Vol 19 (20) ◽  
pp. 13289-13308 ◽  
Author(s):  
Yuliang Liu ◽  
Wei Nie ◽  
Zheng Xu ◽  
Tianyi Wang ◽  
Ruoxian Wang ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Nitrous Acid ◽  
Heterogeneous Reaction ◽  
Total Concentration ◽  
Eastern China ◽  
Mean Value ◽  
Budget Analysis ◽  
Conversion Frequency ◽  
Yearly Average ◽  
Quantitative Understanding

Abstract. Nitrous acid (HONO), an important precursor of the hydroxyl radical (OH), has long been recognized as of significance to atmospheric chemistry, but its sources are still debated. In this study, we conducted continuous measurement of HONO from November 2017 to November 2018 at the SORPES station in Nanjing of eastern China. The yearly average mixing ratio of observed HONO was 0.69±0.58 ppb, showing a larger contribution to OH relative to ozone with a mean OH production rate of 1.16 ppb h−1. To estimate the effect of combustion emissions of HONO, the emitted ratios of HONO to NOx were derived from 55 fresh plumes (NO∕NOx > 0.85), with a mean value of 0.79 %. During the nighttime, the chemistry of HONO was found to depend on RH, and heterogeneous reaction of NO2 on an aerosol surface was presumably responsible for HONO production. The average nighttime NO2-to-HONO conversion frequency (CHONO) was determined to be 0.0055±0.0032 h−1 from 137 HONO formation cases. The missing source of HONO around noontime seemed to be photo-induced, with an average Punknown of 1.04 ppb h−1, based on a semi-quantitative HONO budget analysis. An over-determined system of equations was applied to obtain the monthly variations in nocturnal HONO sources. Besides the burning-emitted HONO (accounting for about 23 % of the total concentration), the contribution of HONO formed heterogeneously on ground surfaces to measured HONO was an approximately constant proportion of 36 % throughout the year. The soil emission revealed clear seasonal variation and contributed up to 40 % of observed HONO in July and August. A higher propensity for generating HONO on aerosol surfaces occurred in severe hazes (accounting for 40 % of the total concentration in January). Our results highlight ever-changing contributions of HONO sources and encourage more long-term observations to evaluate the contributions from varied sources.

scholarly journals Regional severe particle pollution and its association with synoptic weather patterns in the Yangtze River Delta region, China

2017 ◽  
Vol 17 (21) ◽  
pp. 12871-12891 ◽  
Author(s):  
Lei Shu ◽  
Min Xie ◽  
Da Gao ◽  
Tijian Wang ◽  
Dexian Fang ◽  
...  
Keyword(s):  
Yangtze River Delta ◽  
Mean Value ◽  
Air Masses ◽  
Weather Patterns ◽  
Synoptic Weather ◽  
Particle Pollution ◽  
Pm2.5 And Pm10 ◽  
Marine Air ◽  
The Yrd ◽  
The Yangtze River Delta

Abstract. Regional air pollution is significantly associated with dominant weather systems. In this study, the relationship between the particle pollution over the Yangtze River Delta (YRD) region and weather patterns is investigated. First, the pollution characteristics of particles in the YRD are studied using in situ monitoring data (PM2.5 and PM10) in 16 cities and Terra/MODIS AOD (aerosol optical depth) products collected from December 2013 to November 2014. The results show that the regional mean value of AOD is high in the YRD, with an annual mean value of 0.71±0.57. The annual mean particle concentrations in the cities of Jiangsu Province all exceed the national air quality standard. The pollution level is higher in inland areas, and the highest concentrations of PM2.5 and PM10 are 79 and 130 µg m−3, respectively, in Nanjing. The PM2.5  :  PM10 ratios are typically high, thus indicating that PM2.5 is the overwhelmingly dominant particle pollutant in the YRD. The wintertime peak of particle concentrations is tightly linked to the increased emissions during the heating season as well as adverse meteorological conditions. Second, based on NCEP (National Center for Environmental Prediction) reanalysis data, synoptic weather classification is conducted and five typical synoptic patterns are objectively identified. Finally, the synthetic analysis of meteorological fields and backward trajectories are applied to further clarify how these patterns impact particle concentrations. It is demonstrated that air pollution is more or less influenced by high-pressure systems. The relative position of the YRD to the anti-cyclonic circulation exerts significant effects on the air quality of the YRD. The YRD is largely influenced by polluted air masses from the northern and the southern inland areas when it is located at the rear of the East Asian major trough. The significant downward motion of air masses results in stable weather conditions, thereby hindering the diffusion of air pollutants. Thus, this pattern is quite favorable for the accumulation of pollutants in the YRD, resulting in higher regional mean PM10 (116.5 ± 66.9 µg m−3), PM2.5 (75.9 ± 49.9 µg m−3), and AOD (0.74) values. Moreover, this pattern is also responsible for the occurrence of most large-scale regional PM2.5 (70.4 %) and PM10 (78.3 %) pollution episodes. High wind speed and clean marine air masses may also play important roles in the mitigation of pollution in the YRD. Especially when the clean marine air masses account for a large proportion of all trajectories (i.e., when the YRD is affected by the cyclonic system or oceanic circulation), the air in the YRD has a lesser chance of being polluted. The observed correlation between weather patterns and particle pollution can provide valuable insight into making decisions about pollution control and mitigation strategies.

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