scholarly journals Dominant synoptic patterns associated with the decay process of PM<sub>2.5</sub> pollution episodes around Beijing

2021 ◽  
Vol 21 (4) ◽  
pp. 2491-2508
Author(s):  
Xiaoyan Wang ◽  
Renhe Zhang ◽  
Yanke Tan ◽  
Wei Yu
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Relative Humidity ◽  
Air Pollutants ◽  
Wet Deposition ◽  
Decay Process ◽  
Synoptic Patterns ◽  
Circulation Patterns ◽  
Autumn And Winter ◽  
Pollution Episodes

Abstract. The variation in the concentrations of ambient PM2.5 (particles with an aerodynamic diameter less than 2.5 µm) generally forms a continuous sawtooth cycle with a recurring smooth increase followed by a sharp decrease. The episode of abrupt decay of pollution is mostly meteorological in origin and is controlled by the passage of synoptic systems. One affordable and effective measure for quickly reducing PM2.5 concentrations in northern China is to wait for a strong wind to arrive. However, it is still unclear how strong the wind needs to be and exactly what kind of synoptic system most effectively results in the rapid decay of air pollution episodes. PM2.5 variations over the 28 pollution channel cities of the Beijing region are investigated to determine the mechanisms by which synoptic patterns affect the decay processes of pollution episodes. This work shows more obvious day-to-day variations in PM2.5 concentration in winter than in summer, which implies that wintertime PM2.5 variations are more sensitive to meteorological factors. There were 365 decay processes from January 2014 to March 2020, and 97 of them were related to the effective wet deposition. In total, 26 %–43 % of PM2.5 pollutant is removed by the wet deposition in different seasons. Two dominant circulation patterns are identified in summer. All the other three seasons have three circulation types (CTs), respectively. The three CTs in spring show the same patterns as those in autumn and winter. The circulation patterns beneficial to the decay processes all exhibit a higher-than-normal surface wind speed, a negative relative humidity anomaly and net outflow of PM2.5 from the domain. In addition, CT1 in spring, autumn and winter is controlled by northeasterly wind and features the most significant horizontal net outflow of air pollutants and effective upward spread of air pollutants to the free atmosphere. CT2 is the most frequent CT in autumn and winter, with the highest wind speed from the northwest, highest boundary layer height (BLH) and lowest relative humidity among the three CTs, all of which are favorable for the reduction of PM2.5 concentrations. In CT3, strong vertical wind shear within the boundary layer enhances the mixing of surface air pollutants, which is the extra cleaning mechanism besides dry and clean air mass inflow. PM2.5 concentrations show significant decreases of more than 37 %, 41 % and 27 % after the passage of CT1, CT2 and CT3, respectively. A dry airflow with a positive BLH anomaly and the effective horizontal outflow of air pollutants are the main reasons for the abrupt decay phase in summer. PM2.5 concentrations after the decay process show a significant decreasing trend from 2014 to 2020, reflecting successful emission mitigation. Emission reductions have led to a 4.3–5.7 µgm-3yr-1 decrease in PM2.5 concentrations in the 28 pollution channel cities of the Beijing region.

scholarly journals Dominant synoptic patterns associated with the decay process of PM<sub>2.5</sub> pollution episodes around Beijing

2020 ◽  
Author(s):  
Xiaoyan Wang ◽  
Renhe Zhang ◽  
Yanke Tan ◽  
Wei Yu
Keyword(s):  
Boundary Layer ◽  
Relative Humidity ◽  
Air Pollutants ◽  
Wet Deposition ◽  
Decay Process ◽  
Horizontal Wind ◽  
Synoptic Patterns ◽  
Circulation Patterns ◽  
Autumn And Winter ◽  
Pollution Episodes

Abstract. The variation in the concentrations of ambient PM2.5 (particles with an aerodynamic diameter less than 2.5 μm) generally forms a continuous sawtooth cycle with a recurring smooth increase followed by a sharp decrease. The abrupt decay of pollution episode is mostly meteorological in origin, and is controlled by the passage of synoptic systems. One affordable and effective measure for the quickly reducing PM2.5 concentrations in northern China is to wait for strong wind to arrive. However, it is still unclear how strong the wind needs to be and exactly what kind of synoptic system most effectively results in the rapid decay of air pollution episodes. PM2.5 variations over the 28 pollution channel cities of Beijing are investigated to determine the mechanisms by which synoptic patterns affect the decay processes of pollution episodes. This work shows more obvious day-to-day variations in PM2.5 concentration in winter than in summer, which implies that wintertime PM2.5 variations are more sensitive to meteorological factors. There were 365 decay processes from January 2014 to March 2020, and 97 of them were related to the effective wet deposition. 26 %~43 % of PM2.5 pollutant is removed by the wet deposition in different seasons. Two dominant circulation patterns are identified in summer, and the same three circulation types (CTs) are identified in the other three seasons based on the dry-day cases. The circulation patterns beneficial to the decay processes all exhibit a higher than normal surface wind speed, a negative relative humidity anomaly and positive divergence in the PM2.5 horizontal flux. In addition, CT1 in spring, autumn and winter is controlled by northeasterly wind and features the most significant horizontal net-outflow of air pollutants and effective upward spread of air pollutants to the free atmosphere, which promotes the abrupt reduction of local PM2.5 concentrations. CT2 is the most frequent synoptic pattern leading to decay processes in autumn and winter, and the domain region is located to the east of an anticyclone system. CT2 features a strong northwesterly wind of 2.98~3.88 m/s, the lowest relative humidity and the highest boundary layer height (BLH) among the three CTs, all of which are favorable for the reduction of PM2.5 concentrations. In CT3, a prevailing westerly wind anomaly occurs in the domain, with remarkable zonal divergence in the PM2.5 flux and strong horizontal wind shear in the near-surface under the boundary layer. PM2.5 concentrations show significant decreases of more than 37 %, 41 % and 27 % after the passage of CT1, CT2 and CT3, respectively. A dry air mass with a positive BLH anomaly and the effective horizontal outflow of air pollutants are the main reasons for the abrupt decay phase in summer. PM2.5 concentrations after the decay process show a significant decreasing trend from 2014 to 2020, reflecting successful emission mitigation. Emission reductions have led to a 4.3~5.7 μg/(m3.yr) decrease in PM2.5 concentrations in the 28 pollution channel cities of Beijing.

scholarly journals Evaluation of the AMPS Boundary Layer Simulations on the Ross Ice Shelf, Antarctica, with Unmanned Aircraft Observations

2017 ◽  
Vol 56 (8) ◽  
pp. 2239-2258 ◽  
Author(s):  
Jonathan D. Wille ◽  
David H. Bromwich ◽  
John J. Cassano ◽  
Melissa A. Nigro ◽  
Marian E. Mateling ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Relative Humidity ◽  
High Wind ◽  
Ice Shelf ◽  
High Wind Speed ◽  
Near Surface ◽  
Ross Ice Shelf ◽  
Low Cloud ◽  
The Antarctic

AbstractAccurately predicting moisture and stability in the Antarctic planetary boundary layer (PBL) is essential for low-cloud forecasts, especially when Antarctic forecasters often use relative humidity as a proxy for cloud cover. These forecasters typically rely on the Antarctic Mesoscale Prediction System (AMPS) Polar Weather Research and Forecasting (Polar WRF) Model for high-resolution forecasts. To complement the PBL observations from the 30-m Alexander Tall Tower! (ATT) on the Ross Ice Shelf as discussed in a recent paper by Wille and coworkers, a field campaign was conducted at the ATT site from 13 to 26 January 2014 using Small Unmanned Meteorological Observer (SUMO) aerial systems to collect PBL data. The 3-km-resolution AMPS forecast output is combined with the global European Centre for Medium-Range Weather Forecasts interim reanalysis (ERAI), SUMO flights, and ATT data to describe atmospheric conditions on the Ross Ice Shelf. The SUMO comparison showed that AMPS had an average 2–3 m s−1 high wind speed bias from the near surface to 600 m, which led to excessive mechanical mixing and reduced stability in the PBL. As discussed in previous Polar WRF studies, the Mellor–Yamada–Janjić PBL scheme is likely responsible for the high wind speed bias. The SUMO comparison also showed a near-surface 10–15-percentage-point dry relative humidity bias in AMPS that increased to a 25–30-percentage-point deficit from 200 to 400 m above the surface. A large dry bias at these critical heights for aircraft operations implies poor AMPS low-cloud forecasts. The ERAI showed that the katabatic flow from the Transantarctic Mountains is unrealistically dry in AMPS.

scholarly journals Observed Sensitivity of Low-Cloud Radiative Effects to Meteorological Perturbations over the Global Oceans

2020 ◽  
Vol 33 (18) ◽  
pp. 7717-7734
Author(s):  
Ryan C. Scott ◽  
Timothy A. Myers ◽  
Joel R. Norris ◽  
Mark D. Zelinka ◽  
Stephen A. Klein ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Relative Humidity ◽  
Surface Temperature ◽  
Sea Surface ◽  
Cloud Feedbacks ◽  
Low Level ◽  
Low Clouds ◽  
Low Cloud ◽  
Global Oceans

AbstractUnderstanding how marine low clouds and their radiative effects respond to changing meteorological conditions is crucial to constrain low-cloud feedbacks to greenhouse warming and internal climate variability. In this study, we use observations to quantify the low-cloud radiative response to meteorological perturbations over the global oceans to shed light on physical processes governing low-cloud and planetary radiation budget variability in different climate regimes. We assess the independent effect of perturbations in sea surface temperature, estimated inversion strength, horizontal surface temperature advection, 700-hPa relative humidity, 700-hPa vertical velocity, and near-surface wind speed. Stronger inversions and stronger cold advection greatly enhance low-level cloudiness and planetary albedo in eastern ocean stratocumulus and midlatitude regimes. Warming of the sea surface drives pronounced reductions of eastern ocean stratocumulus cloud amount and optical depth, and hence reflectivity, but has a weaker and more variable impact on low clouds in the tropics and middle latitudes. By reducing entrainment drying, higher free-tropospheric relative humidity enhances low-level cloudiness. At low latitudes, where cold advection destabilizes the boundary layer, stronger winds enhance low-level cloudiness; by contrast, wind speed variations have weak influence at midlatitudes where warm advection frequently stabilizes the marine boundary layer, thus inhibiting vertical mixing. These observational constraints provide a framework for understanding and evaluating marine low-cloud feedbacks and their simulation by models.

scholarly journals Marine aerosol properties over the Southern Ocean in relation to the wintertime meteorological conditions

2022 ◽  
Vol 22 (1) ◽  
pp. 119-137
Author(s):  
Manu Anna Thomas ◽  
Abhay Devasthale ◽  
Michael Kahnert
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Relative Humidity ◽  
Southern Ocean ◽  
Surface Wind ◽  
Ocean Surface ◽  
Meteorological Conditions ◽  
Sea Salt ◽  
Aerosol Backscatter ◽  
Aerosol Properties

Abstract. Given the vast expanse of oceans on our planet, marine aerosols (and sea salt in particular) play an important role in the climate system via multitude of direct and indirect effects. The efficacy of their net impact, however, depends strongly on the local meteorological conditions that influence their physical, optical and chemical properties. Understanding the coupling between aerosol properties and meteorological conditions is therefore important. It has been historically difficult to statistically quantify this coupling over larger oceanic areas due to the lack of suitable observations, leading to large uncertainties in the representation of aerosol processes in climate models. Perhaps no other region shows higher uncertainties in the representation of marine aerosols and their effects than the Southern Ocean. During winter the Southern Ocean boundary layer is dominated by sea salt emissions. Here, using 10 years of austral winter period (June, July and August, 2007–2016) space-based aerosol profiling by CALIOP-CALIPSO in combination with meteorological reanalysis data, we investigated the sensitivity of marine aerosol properties over the Southern Ocean (40–65∘ S) to various meteorological parameters, such as vertical relative humidity (RH), surface wind speed and sea surface temperature (SST) in terms of joint histograms. The sensitivity study is done for the climatological conditions and for the enhanced cyclonic and anticyclonic conditions in order to understand the impact of large-scale atmospheric circulation on the aerosol properties. We find a clear demarcation in the 532 nm aerosol backscatter and extinction at RH around 60 %, irrespective of the state of the atmosphere. The backscatter and extinction increase at higher relative humidity as a function of surface wind speed. This is mainly because of the water uptake by the wind-driven sea salt aerosols at high RH near the ocean surface resulting in an increase in size, which is confirmed by the decreased depolarization for the wet aerosols. An increase in aerosol backscatter and extinction is observed during the anticyclonic conditions compared to cyclonic conditions for the higher wind speeds and relative humidity, mainly due to aerosols being confined to the boundary layer, and their proximity to the ocean surface facilitates the growth of the particles. We further find a very weak dependency of aerosol backscatter on SSTs at lower wind speeds. However, when the winds are stronger than about 12 m s−1, the backscattering coefficient generally increases with SST. When aerosol properties are investigated in terms of aerosol verticality and in relation to meteorological parameters, it is seen that the aerosol backscatter values in the free troposphere (pressure <850 hPa) are much lower than in the boundary layer, irrespective of the RH and the three weather states. This indicates that the local emissions from the ocean surface make the dominant contribution to aerosol loads over the Southern Ocean. A clear separation of particulate depolarization is observed in the free and lower troposphere, more prominent in the climatological mean and the cyclonic states. For RH > 60 %, low depolarization values are noticeable in the lower troposphere, which is an indication of the dominance of water-coated and mostly spherical sea salt particles. For RH < 60 %, there are instances when the aerosol depolarization increases in the boundary layer; this is more prominent in the mean and anticyclonic cases, which can be associated with the presence of drier aerosol particles. Based on the joint histograms investigated here, we provide third-degree polynomials to obtain aerosol extinction and backscatter as a function of wind speed and relative humidity. Additionally, backscattering coefficient is also expressed jointly in terms of wind speed and sea surface temperature. Furthermore, depolarization is expressed as a function of relative humidity. These fitting functions would be useful to test and improve the parameterizations of sea salt aerosols in the climate models. We also note some limitations of our study. For example, interpreting the verticality of aerosol properties (especially depolarization) in relation to the meteorological conditions in the free and upper troposphere (pressure <850 hPa) was challenging. Furthermore, we do not see any direct evidence of sudden crystallization (efflorescence), deliquescence or hysteresis effects of the aerosols. Observing such effects will likely require a targeted investigation of individual cases considering tracer transport, rather than the statistical sensitivity study that entails temporally and geographically averaged large data sets.

scholarly journals The short-term associations of chronic obstructive pulmonary disease hospitalizations with meteorological factors and air pollutants in Southwest China: a time-series study

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Meng Li ◽  
Shengqi Chen ◽  
Hanqing Zhao ◽  
Chengxiang Tang ◽  
Yunfeng Lai ◽  
...  
Keyword(s):  
Chronic Obstructive Pulmonary Disease ◽  
Time Series ◽  
Wind Speed ◽  
Relative Humidity ◽  
Low Temperature ◽  
Air Pollutants ◽  
Meteorological Factors ◽  
Chronic Obstructive ◽  
Extreme Temperatures ◽  
Obstructive Pulmonary Disease

AbstractChronic obstructive pulmonary disease (COPD) is the fourth major cause of mortality and morbidity worldwide and is projected to be the third by 2030. However, there is little evidence available on the associations of COPD hospitalizations with meteorological factors and air pollutants in developing countries/regions of Asia. In particular, no study has been done in western areas of China considering the nonlinear and lagged effects simultaneously. This study aims to evaluate the nonlinear and lagged associations of COPD hospitalizations with meteorological factors and air pollutants using time-series analysis. The modified associations by sex and age were also investigated. The distributed lag nonlinear model was used to establish the association of daily COPD hospitalizations of all 441 public hospitals in Chengdu, China from Jan/2015–Dec/2017 with the ambient meteorological factors and air pollutants. Model parameters were optimized based on quasi Akaike Information Criterion and model diagnostics was conducted by inspecting the deviance residuals. Subgroup analysis by sex and age was also performed. Temperature, relative humidity, wind and Carbon Monoxide (CO) have statistically significant and consistent associations with COPD hospitalizations. The cumulative relative risk (RR) was lowest at a temperature of 19℃ (relative humidity of 67%). Both extremely high and low temperature (and relative humidity) increase the cumulative RR. An increase of wind speed above 4 mph (an increase of CO above 1.44 mg/m3) significantly decreases (increases) the cumulative RR. Female populations were more sensitive to low temperature and high CO level; elderly (74+) populations are more sensitive to high relative humidity; younger populations (< = 74) are more susceptible to CO higher than 1.44 mg/m3. Therefore, people with COPD should avoid exposure to adverse environmental conditions of extreme temperatures and relative humidity, low wind speed and high CO level, especially for female and elderly patients who were more sensitive to extreme temperatures and relative humidity.

scholarly journals Determination of Some Air Pollutants andMeteorological Parameters in Abattoir, NTAK INYANG in UYO L.G.A of AKWA IBOM State in Nigeria

2020 ◽  
pp. 1-8
Author(s):  
Jonah, A. E
Keyword(s):  
Wind Speed ◽  
Relative Humidity ◽  
Air Pollutants ◽  
Quality Index ◽  
Positive Relationship ◽  
Negative Relationship ◽  
Analytical Techniques ◽  
Air Pollutant ◽  
Standard Limit

The determination of air pollutants in Abattoir, Ntak Inyang in Uyo L.G.A was carried out using standard analytical techniques. The pollutants monitored were NO2, SO2, H2S, CO, NH3, Cl2, TVOC, CH2O, PM2.5, PM10, Temp, Relative humidity (RH), Pressure and Wind Speed (WS). The results for the concentration of air pollutant and their Air Quality Index (AQI) reveals as follows NO2(1.36 ± 0.32(ppm), AQ1=1360). SO2(2.44 ± 1.98(ppm), AQ1=488). H2S (3.38 ± 1940(ppm), AQ1=19450). CO (1.79±1.61(ppm), AQ1=334). NH3(7.8±2.26(ppm), AQ1=156). Cl2(1.47± 1.29(ppm), AQ1= 147). HCN (11.56±7.93(mg/m3), AQ1=115,600). TVOC (164±0.46(mg/m3), AQ1=328). CH2O (0.23±0.12(mg/m3), AQ1=0.276). PM2.5(43.2±0.95(μg/m3), AQ1=172.8). PM10(74.8±1.15(μg/m3), AQ1=149.6). Temp (27.5±4.6oC). Relative humidity (RH) (74.6 ± 4.6%), Press (1006.7±0.84(kpa). W.S (1.56±0(m/s)). The result showed that NO2, SO2, H2S, CO, NH3, Cl2, HCN, TVOC, PM2.5and PM10were higher than that of FEPA standard limit. The correlation analysis revealed that NO2shows positive relationship with H2S, and W.S at 0.05 significant level and negatively with Cl2and Press at 0.01 significant level, and negatively with PM2.5and PM10 at 0.05 significant level. SO2correlated positively with CO at 0.01 significant level, TVOC and CH2O at 0.05 significant level. SO2-NH3at 0.05 significant level but negatively. H2S shows a relationship with Temp but positively at 0.01 significant leveland 0.05 significant level with HCN, H2S also correlated negatively with NH3and Press at 0.01 significant level. While CO shows a correlation with NH3at 0.05 significant level but negatively. NH3-RH positively at 0.01 significant, NH3-Press at 0.05 significant level. Also, NH3shows a negative relationship with TVOC, CH2O and Temp at 0.05 significant level. Cl2correlated strongly but positively with Press at 0.01significant level, Cl2-PM2.5and PM10at 0.05 significant level and a negative relationship with W.S at 0.05 significant level. HCN-WS negatively at a 0.05 significant level. TVOC correlated positively with CH2O and negatively with RH at 0.01 significant level, and a positive relationship with PM2.5and PM10at 0.05 significant level. CH2O correlated negatively with RH at 0.01 significant level and positively with PM2.5and PM10at 0.05 significant level. PM2.5 shows a positively relationship with PM10at 0.01 significant level. This result in an indication of the presence of possible air pollutants in the of the study area which may results in many health problems.

scholarly journals Feedback effects of boundary-layer meteorological factors on cumulative explosive growth of PM<sub>2.5</sub> during winter heavy pollution episodes in Beijing from 2013 to 2016

2018 ◽  
Vol 18 (1) ◽  
pp. 247-258 ◽  
Author(s):  
Junting Zhong ◽  
Xiaoye Zhang ◽  
Yunsheng Dong ◽  
Yaqiang Wang ◽  
Cheng Liu ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Relative Humidity ◽  
Meteorological Factors ◽  
Meteorological Data ◽  
Heterogeneous Reactions ◽  
Hygroscopic Growth ◽  
Surface Cooling ◽  
Boundary Layer Height ◽  
Aerosol Pollution ◽  
Pollution Episodes

Abstract. In January 2013, February 2014, December 2015 and December 2016 to 10 January 2017, 12 persistent heavy aerosol pollution episodes (HPEs) occurred in Beijing, which received special attention from the public. During the HPEs, the precise cause of PM2.5 explosive growth (mass concentration at least doubled in several hours to 10 h) is uncertain. Here, we analyzed and estimated relative contributions of boundary-layer meteorological factors to such growth, using ground and vertical meteorological data. Beijing HPEs are generally characterized by the transport stage (TS), whose aerosol pollution formation is primarily caused by pollutants transported from the south of Beijing, and the cumulative stage (CS), in which the cumulative explosive growth of PM2.5 mass is dominated by stable atmospheric stratification characteristics of southerly slight or calm winds, near-ground anomalous inversion, and moisture accumulation. During the CSs, observed southerly weak winds facilitate local pollutant accumulation by minimizing horizontal pollutant diffusion. Established by TSs, elevated PM2.5 levels scatter more solar radiation back to space to reduce near-ground temperature, which very likely causes anomalous inversion. This surface cooling by PM2.5 decreases near-ground saturation vapor pressure and increases relative humidity significantly; the inversion subsequently reduces vertical turbulent diffusion and boundary-layer height to trap pollutants and accumulate water vapor. Appreciable near-ground moisture accumulation (relative humidity> 80 %) would further enhance aerosol hygroscopic growth and accelerate liquid-phase and heterogeneous reactions, in which incompletely quantified chemical mechanisms need more investigation. The positive meteorological feedback noted on PM2.5 mass explains over 70 % of cumulative explosive growth.

Trends of Estimated Potential Evapotranspiration in the Poyang Lake Basin, China

2013 ◽  
Vol 726-731 ◽  
pp. 3299-3302 ◽  
Author(s):  
Xu Chun Ye ◽  
Jian Liu ◽  
Qi Zhang
Keyword(s):  
Wind Speed ◽  
Relative Humidity ◽  
Poyang Lake ◽  
Potential Evapotranspiration ◽  
Sunshine Duration ◽  
Lake Basin ◽  
Catchment Scale ◽  
Poyang Lake Basin ◽  
Autumn And Winter

Using the Penman-Monteith method, the potential evapotranspiration (PET) was calculated over the Poyang Lake basin during 1960-2008. Our analysis indicates that except spring, PET in summer, autumn and winter shows long term decreasing trend, with the largest in summer and the least in winter. The decrease of annual PET in the Poyang Lake basin is mostly affected by the decline of summer PET. On catchment scale, although the calculated PET at all the Metero-stations shows decrease trend, the trends are not significant at some stations. Further analysis indicates that the most important predictor for the decreasing trend in potential evapotranspiration is sunshine duration and wind speed, followed by relative humidity and air temperature.

scholarly journals Spatiotemporal Variations of Particulate and Gaseous Pollutants and Their Relations to Meteorological Parameters: The Case of Xiangyang, China

2019 ◽  
Vol 17 (1) ◽  
pp. 136
Author(s):  
Wei Xue ◽  
Qingming Zhan ◽  
Qi Zhang ◽  
Zhonghua Wu
Keyword(s):  
Air Quality ◽  
Wind Speed ◽  
Relative Humidity ◽  
Air Pollutants ◽  
Meteorological Parameters ◽  
Air Pollutant ◽  
Weekend Effect ◽  
Gaseous Pollutants ◽  
Statistical Point ◽  
Particulate Pollutants

High air pollution levels have become a nationwide problem in China, but limited attention has been paid to prefecture-level cities. Furthermore, different time resolutions between air pollutant level data and meteorological parameters used in many previous studies can lead to biased results. Supported by synchronous measurements of air pollutants and meteorological parameters, including PM2.5, PM10, total suspended particles (TSP), CO, NO2, O3, SO2, temperature, relative humidity, wind speed and direction, at 16 urban sites in Xiangyang, China, from 1 March 2018 to 28 February 2019, this paper: (1) analyzes the overall air quality using an air quality index (AQI); (2) captures spatial dynamics of air pollutants with pollution point source data; (3) characterizes pollution variations at seasonal, day-of-week and diurnal timescales; (4) detects weekend effects and holiday (Chinese New Year and National Day holidays) effects from a statistical point of view; (5) establishes relationships between air pollutants and meteorological parameters. The principal results are as follows: (1) PM2.5 and PM10 act as primary pollutants all year round and O3 loses its primary pollutant position after November; (2) automobile manufacture contributes to more particulate pollutants while chemical plants produce more gaseous pollutants. TSP concentration is related to on-going construction and road sprinkler operations help alleviate it; (3) an unclear weekend effect for all air pollutants is confirmed; (4) celebration activities for the Chinese New Year bring distinctly increased concentrations of SO2 and thereby enhance secondary particulate pollutants; (5) relative humidity and wind speed, respectively, have strong negative correlations with coarse particles and fine particles. Temperature positively correlates with O3.

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