scholarly journals Investigating the impact of regional transport on PM<sub>2.5</sub> formation using vertical observation during APEC 2014 Summit in Beijing

2016 ◽  
Vol 16 (24) ◽  
pp. 15451-15460 ◽  
Author(s):  
Yang Hua ◽  
Shuxiao Wang ◽  
Jiandong Wang ◽  
Jingkun Jiang ◽  
Tianshu Zhang ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Fine Particulate Matter ◽  
Ground Level ◽  
Meteorological Conditions ◽  
Point Sources ◽  
Asia Pacific ◽  
Rural Site ◽  
Regional Transport ◽  
Observation Methods ◽  
The Impact

Abstract. During the APEC (Asia-Pacific Economic Cooperation) Economic Leaders' 2014 Summit in Beijing, strict regional air emission controls were implemented, providing a unique opportunity to investigate the transport and formation mechanism of fine particulate matter (PM2.5). This study explores the use of vertical observation methods to investigate the influence of regional transport on PM2.5 pollution in Beijing before and during the APEC Summit. Vertical profiles of extinction coefficient, wind, temperature and relative humidity were monitored at a rural site on the border of Beijing and Hebei Province. Three PM2.5 pollution episodes were analyzed. In episode 1 (27 October to 1 November), regional transport accompanied by the accumulation of pollutants under unfavorable meteorological conditions led to the pollution. In episode 2 (2–5 November), pollutants left from episode 1 were retained in the boundary layer of the region for 2 days and then settled down to the surface, leading to an explosive increase of PM2.5. The regional transport of aged aerosols played a crucial role in the heavy PM2.5 pollution. In episode 3 (6–11 November), emissions from large point sources had been controlled for several days while primary emissions from diesel vehicles might have led to the pollution. It is found that ground-level observation of meteorological conditions and air quality could not fully explain the pollution process, while vertical parameters (aerosol optical properties, winds, relative humidity and temperature) improved the understanding of regional transport influence on heavy pollution processes. Future studies may consider including vertical observations to aid investigation of pollutant transport, especially during episodic events of rapidly increasing concentrations.

scholarly journals Investigating the impact of regional transport on PM<sub>2.5</sub> formation using vertical observation during APEC 2014 Summit in Beijing

2016 ◽  
Author(s):  
Yang Hua ◽  
Shuxiao Wang ◽  
Jiandong Wang ◽  
Jingkun Jiang ◽  
Tianshu Zhang ◽  
...  
Keyword(s):  
Fine Particulate Matter ◽  
Ground Level ◽  
Point Sources ◽  
Asia Pacific ◽  
Regional Transport ◽  
Observation Methods ◽  
Pollutants Transport ◽  
Accumulation Of Pollutants ◽  
Primary Emissions ◽  
The Impact

Abstract. During APEC (Asia-Pacific Economic Cooperation) Economic Leaders' 2014 Summit in Beijing, strict regional air emission control was implemented, providing a unique opportunity to investigate the transport and formation mechanism of fine particulate matter (PM2.5). This study explores the use of vertical observation methods to investigate the influence of regional transport on PM2.5 pollution in Beijing before and during the APEC Summit. Vertical profiles of extinction coefficient, wind, temperature and relative humidity were monitored. Three PM2.5 pollution episodes were analysed. In episode 1 (October 27th to November 1st), regional transport accompanied with the accumulation of pollutants under unfavourable meteorological conditions led to the pollution. In episode 2 (November 2nd to 5th), pollutants left from episode 1 were retained in the boundary layer for 2 days in the region and then settled down to the surface, leading to an explosive increase of PM2.5. The regional transport of aged aerosols played a crucial role in the heavy PM2.5 pollution. In episode 3 (November 6th to 11th), emission from large point sources had been controlled for several days while primary emissions from diesel vehicle might lead to the pollution. It is found that ground-level observation of meteorology condition and air quality could not fully explain the pollution process while vertical parameters (aerosol optical profile, wind profile, relatively humidity profile and temperature profile) improved the understanding of regional transport influence on heavy pollution process. Further vertical observations are needed to investigate the pollutants transport especially during the explosive increase pollution episode.

Examining the accuracy of satellite retrievals of trace-gas emissions and lifetimes using high-resolution plume modelling.

2021 ◽  
Author(s):  
Zoe Davis ◽  
Debora Griffin ◽  
Yue Jia ◽  
Susann Tegtmeier ◽  
Mallory Loria ◽  
...  
Keyword(s):  
Wind Direction ◽  
Vertical Profile ◽  
Trace Gases ◽  
Meteorological Conditions ◽  
Point Sources ◽  
Satellite Observations ◽  
Trace Gas ◽  
Vertical Column ◽  
Retrieval Method ◽  
The Impact

&lt;p&gt;A recent method uses satellite measurements to estimate lifetimes and emissions of trace-gases from point sources (Fioletov et al., 2015). Emissions are retrieved by fitting measured vertical column densities (VCDs) of trace-gases to a three-dimensional function of the wind speed and spatial coordinates. In this study, a plume model generated &amp;#8220;synthetic&amp;#8221; satellite observations of prescribed emissions to examine the accuracy of the retrieved emissions. The Lagrangian transport and dispersion model FLEXPART (v10.0) modelled the plume from a point source over a multi-day simulation period at a resolution much higher than current satellite observations. The study aims to determine how various assumptions in the retrieval method and local meteorological conditions affect the accuracy and precision of emissions. These assumptions include that the use of a vertical mean of the wind profile is representative of the transport of the plume&amp;#8217;s vertical column. In the retrieval method, the VCDs&amp;#8217; pixel locations are rotated around the source based on wind direction so that all plumes have a common wind direction. Retrievals using a vertical mean wind for rotation will be compared to retrievals using VCDs determined by rotating each altitude of the vertical profile of trace-gas using the respective wind-direction. The impact of local meteorological factors on the two approaches will be presented, including atmospheric mixing, vertical wind shear, and boundary layer height. The study aims to suggest which altitude(s) of the vertical profile of winds results in the most accurate retrievals given the local meteorological conditions. The study will also examine the impact on retrieval accuracy due to satellite resolution, trace-gas lifetime, plume source altitude, number of overpasses, and random and systematic errors. Sensitivity studies repeated using a second, &amp;#8220;line-density&amp;#8221;, retrieval method will also be presented (Adams et al., 2019; Goldberg et al., 2019).&lt;/p&gt;

scholarly journals Evident PM<sub>2.5</sub> Drops in the East of China due to the COVID-19 Quarantines in February

2020 ◽  
Author(s):  
Zhicong Yin ◽  
Yijia Zhang ◽  
Huijun Wang ◽  
Yuyan Li
Keyword(s):  
Emergency Response ◽  
Yangtze River ◽  
North China ◽  
Fine Particulate Matter ◽  
Yangtze River Delta ◽  
Meteorological Conditions ◽  
Pollution Regulation ◽  
Fine Particulate ◽  
Haze Pollution ◽  
The Impact

Abstract. The top-level emergency response to the COVID-19 pandemic involved an exhaustive quarantine in China. The impacts of COVID-19 quarantine on the decline in fine particulate matter (PM2.5) were quantitatively assessed based on numerical simulations and observations in February. The stable meteorological conditions in February 2020 caused considerable PM2.5 anomalies that were eliminated in advance. The contributions of routine emission reductions were also quantitatively extrapolated. The top-level emergency response substantially alleviated the level of haze pollution in the east of China. Although climate variability elevated the PM2.5 by 29 % (relative to 2020 observations), 59 % decline related to COVID-19 pandemic and 20 % decline from the expected pollution regulation dramatically exceeded the former in North China. The COVID-19 quarantine measures decreased the PM2.5 in Yangtze River Delta by 72 %. In Hubei Province where most pneumonia cases were confirmed, the impact of total emission reduction (72 %) evidently exceeded the rising percentage of PM2.5 driven by meteorology (13 %).

scholarly journals The Impact of the Lockdown Caused by the COVID-19 Pandemic on the Fine Particulate Matter (PM2.5) Air Pollution: The Greek Paradigm

2021 ◽  
Vol 18 (13) ◽  
pp. 6748
Author(s):  
Ourania S. Kotsiou ◽  
Georgios K. D. Saharidis ◽  
Georgios Kalantzis ◽  
Evangelos C. Fradelos ◽  
Konstantinos I. Gourgoulianis
Keyword(s):  
Air Pollution ◽  
Wireless Sensors ◽  
Fine Particulate Matter ◽  
Meteorological Conditions ◽  
Significant Drop ◽  
Fine Particulate ◽  
Guideline Value ◽  
The Mean ◽  
The Impact ◽  
Pm2.5 Concentration

Introduction: Responding to the coronavirus pandemic, Greece implemented the largest quarantine in its history. No data exist regarding its impact on PM2.5 pollution. We aimed to assess PM2.5 levels before, during, and after lockdown (7 March 2020–16 May 2020) in Volos, one of Greece’s most polluted industrialized cities, and compare PM2.5 levels with those obtained during the same period last year. Meteorological conditions were examined as confounders. Methods: The study period was discriminated into three phases (pre-lockdown: 7 March–9 March, lockdown: 10 March–4 May, and post-lockdown period: 5 May–16 May). A wireless sensors network was used to collect PM2.5, temperature, relative humidity, rainfall, and wind speed data every 2 s. Results: The lockdown resulted in a significant drop of PM2.5 by 37.4% in 2020, compared to 2019 levels. The mean daily concentrations of PM2.5 exceeded the WHO’s guideline value for 24-h mean levels of PM2.5 35% of the study period. During the strictest lockdown (23 March to 4 May), the mean daily PM2.5 levels exceeded the standard 41% of the time. The transition from the pre-lockdown period into lockdown or post-lockdown periods was associated with lower PM2.5 concentrations. Conclusions: A reduction in the mean daily PM2.5 concentration was found compared to 2019. Lockdown was not enough to avoid severe exceedances of air pollution in Volos.

Measurements of moisture in smoldering smoke and implications for fog

2006 ◽  
Vol 15 (4) ◽  
pp. 517 ◽  
Author(s):  
Gary L. Achtemeier
Keyword(s):  
Relative Humidity ◽  
Ground Level ◽  
Southern United States ◽  
Formation Temperature ◽  
Mixing Ratio ◽  
Prescribed Burns ◽  
Dry Air ◽  
Ambient Relative Humidity ◽  
Humidity Measurements ◽  
The Impact

Smoke from wildland burning in association with fog has been implicated as a visibility hazard over roadways in the southern United States. A project began in 2002 to determine whether moisture released during the smoldering phases of southern prescribed burns could contribute to fog formation. Temperature and relative humidity measurements were taken from 27 smoldering ‘smokes’ during 2002 and 2003. These data were converted to a measure of the mass of water vapor present to the mass of dry air containing the vapor (smoke mixing ratio). Some smokes were dry with almost no moisture beyond ambient. Other smokes were moist with moisture excesses as large as 39 g kg–1. Calculations show that ground-level smoke moisture excesses have no impact on ambient relative humidity during the day. However, the impact at night can be large enough to increase the ambient relative humidity to 100%. Therefore smoke moisture may be a contributing factor to the location and timing of fog formation.

scholarly journals Shifts in the epidemic season of human respiratory syncytial virus associated with inbound overseas travelers and meteorological conditions in Japan, 2014–2017: An ecological study

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0248932
Author(s):  
Keita Wagatsuma ◽  
Iain S. Koolhof ◽  
Yugo Shobugawa ◽  
Reiko Saito
Keyword(s):  
Respiratory Syncytial Virus ◽  
Relative Humidity ◽  
Meteorological Conditions ◽  
Human Respiratory Syncytial Virus ◽  
Japan Meteorological Agency ◽  
Population Increase ◽  
Epidemic Season ◽  
Mean Temperature ◽  
Syncytial Virus ◽  
The Impact

Few studies have examined the effects of inbound overseas travelers and meteorological conditions on the shift in human respiratory syncytial virus (HRSV) season in Japan. This study aims to test whether the number of inbound overseas travelers and meteorological conditions are associated with the onset week of HRSV epidemic season. The estimation of onset week for 46 prefectures (except for Okinawa prefecture) in Japan for 4-year period (2014–2017) was obtained from previous papers based on the national surveillance data. We obtained data on the yearly number of inbound overseas travelers and meteorological (yearly mean temperature and relative humidity) conditions from Japan National Tourism Organization (JNTO) and Japan Meteorological Agency (JMA), respectively. Multi-level mixed-effects linear regression analysis showed that every 1 person (per 100,000 population) increase in number of overall inbound overseas travelers led to an earlier onset week of HRSV epidemic season in the year by 0.02 week (coefficient –0.02; P<0.01). Higher mean temperature and higher relative humidity were also found to contribute to an earlier onset week by 0.30 week (coefficient –0.30; P<0.05) and 0.18 week (coefficient –0.18; P<0.01), respectively. Additionally, models that included the number of travelers from individual countries (Taiwan, South Korea, and China) except Australia showed that both the number of travelers from each country and meteorological conditions contributed to an earlier onset week. Our analysis showed the earlier onset week of HRSV epidemic season in Japan is associated with increased number of inbound overseas travelers, higher mean temperature, and relative humidity. The impact of international travelers on seasonality of HRSV can be further extended to investigations on the changes of various respiratory infectious diseases especially after the coronavirus disease 2019 (COVID-19) pandemic.

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 Ground-level ozone in four Chinese cities: precursors, regional transport and heterogeneous processes

2014 ◽  
Vol 14 (23) ◽  
pp. 13175-13188 ◽  
Author(s):  
L. K. Xue ◽  
T. Wang ◽  
J. Gao ◽  
A. J. Ding ◽  
X. H. Zhou ◽  
...  
Keyword(s):  
Measurement Techniques ◽  
Peroxy Radical ◽  
Ground Level ◽  
Rural Site ◽  
Regional Transport ◽  
Chinese Cities ◽  
Heterogeneous Processes ◽  
Comparison Of The Results ◽  
In Situ Production

Abstract. We analyzed the measurements of ozone (O3) and its precursors made at rural/suburban sites downwind of four large Chinese cities – Beijing, Shanghai, Guangzhou and Lanzhou, to elucidate their pollution characteristics, regional transport, in situ production, and impacts of heterogeneous processes. The same measurement techniques and observation-based model were used to minimize uncertainties in comparison of the results due to difference in methodologies. All four cities suffered from serious O3 pollution but showed different precursor distributions. The model-calculated in situ O3 production rates were compared with the observed change rates to infer the relative contributions of on-site photochemistry and transport. At the rural site downwind of Beijing, export of the well-processed urban plumes contributed to the extremely high O3 levels (up to an hourly value of 286 ppbv), while the O3 pollution observed at suburban sites of Shanghai, Guangzhou and Lanzhou was dominated by intense in situ production. The O3 production was in a volatile organic compound (VOC)-limited regime in both Shanghai and Guangzhou, and a NOx-limited regime in Lanzhou. The key VOC precursors are aromatics and alkenes in Shanghai, and aromatics in Guangzhou. The potential impacts on O3 production of several heterogeneous processes, namely, hydrolysis of dinitrogen pentoxide (N2O5), uptake of hydro peroxy radical (HO2) on particles and surface reactions of NO2 forming nitrous acid (HONO), were assessed. The analyses indicate the varying and considerable impacts of these processes in different areas of China depending on the atmospheric abundances of aerosol and NOx, and suggest the urgent need to better understand these processes and represent them in photochemical models.

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