scholarly journals Air quality deterioration episode associated with typhoon over the complex topographic environment in central Taiwan

2021 ◽  
Author(s):  
Chuan-Yao Lin ◽  
Yang-Fan Sheng ◽  
Wan-Chin Chen ◽  
Charles C. K. Chou ◽  
Yi-Yun Chien ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Wind Direction ◽  
Air Pollutants ◽  
Sea Breeze ◽  
The Philippines ◽  
Mountain Range ◽  
Research Attention ◽  
Quality Deterioration ◽  
Central Taiwan

Abstract. Air pollution is typically at its lowest in Taiwan during summer. The mean concentrations of PM10, PM2.5, and daytime ozone (08:00–17:00 LST) during summer (June–August) over central Taiwan are 35–40 µg/m3, 18–22 µg/m3, and 30–42 ppb, respectively, between 2004 and 2019. Sampling analysis revealed that the contribution of organic carbon (OC) in PM2.5 could exceed 30 % in urban and inland mountain sites during July in 2017 and 2018. Frequent episodes of air quality deterioration occur over the western plains of Taiwan when an easterly typhoon circulation interacts with the complex topographic structure of the island. We explored an episode of air quality deterioration that was associated with a typhoon between 15 and 17 July 2018, using the Weather Research Forecasting with Chemistry (WRF-Chem) model. The results indicated that the continual formation of low-pressure systems or typhoons in the area between Taiwan and Luzon island in the Philippines provided a strong easterly ambient flow, which lasted for an extended period between 15 and 17 July. The interaction between the easterly flow and Taiwan’s Central Mountain Range (CMR) resulted in stable weather conditions and weak wind speed in western Taiwan during the study period. Numerical modeling also indicated that a lee side vortex easily formation and the wind direction could be changed from southwesterly to northwesterly over central Taiwan because of the interaction between the typhoon circulation and the CMR. The northwesterly wind coupled with a sea breeze was conducive to the transport of air pollutants, from the coastal upstream industrial and urban areas to the inland area. The dynamic process for the wind direction changed given a reasonable explanation why the observed SO42− became the major contributor to PM2.5 during the episode. SO42− contribution proportions (%) to PM2.5 at the coastal, urban, and mountain sites were 9.4 µg/m3 (30.5 %), 12.1 µg/m3 (29.9 %), and 11.6 µg/m3 (29.7 %), respectively. Moreover, the variation of the boundary layer height had a strong effect on the concentration level of both PM2.5 and ozone. The combination of the lee vortex and land-sea breeze, as well as the boundary layer development, were the key mechanisms in air pollutants accumulation and transport. As typhoons frequently occur around Taiwan during summer and fall, and their effect on the island’s air quality merits further research attention.

scholarly journals Air quality deterioration episode associated with a typhoon over the complex topographic environment in central Taiwan

2021 ◽  
Vol 21 (22) ◽  
pp. 16893-16910
Author(s):  
Chuan-Yao Lin ◽  
Yang-Fan Sheng ◽  
Wan-Chin Chen ◽  
Charles C. K. Chou ◽  
Yi-Yun Chien ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Wind Direction ◽  
Sea Breeze ◽  
The Philippines ◽  
Air Pollutant ◽  
Mountain Range ◽  
Research Attention ◽  
Quality Deterioration ◽  
Central Taiwan

Abstract. Air pollution is typically at its lowest in Taiwan during summer. The mean concentrations of PM10, PM2.5, and daytime ozone (08:00–17:00 LST) during summer (June–August) over central Taiwan were 35–40 µg m−3, 18–22 µg m−3, and 30–42 ppb, respectively, between 2004 and 2019. Sampling analysis revealed that the contribution of organic carbon (OC) to PM2.5 could have exceeded 30 % in urban and inland mountain sites during July in 2017 and 2018. Frequent episodes of air quality deterioration occur over the western plains of Taiwan when an easterly typhoon circulation interacts with the complex topographic structure of the island. We explored an episode of air quality deterioration that was associated with a typhoon between 15 and 17 July 2018 using the Weather Research Forecasting with Chemistry (WRF-Chem) model. The results indicated that the continual formation of low-pressure systems or typhoons in the area between Taiwan and Luzon island in the Philippines provided a strong easterly ambient flow, which lasted for an extended period between 15 and 17 July. The interaction between the easterly flow and Taiwan's Central Mountain Range (CMR) resulted in stable weather conditions and weak wind speed in western Taiwan during the study period. Numerical modeling also indicated that a lee side vortex easily formed, and the wind direction could have changed from southwesterly to northwesterly over central Taiwan because of the interaction between the typhoon circulation and the CMR. The northwesterly wind coupled with a sea breeze was conducive to the transport of air pollutants from the coastal upstream industrial and urban areas to the inland area. The dynamic process for the wind direction changed given a reasonable explanation for why the observed SO42- became the major contributor to PM2.5 during the episode. SO42- contribution proportions (%) to PM2.5 at the coastal, urban, and mountain sites were 9.4 µg m−3 (30.5 %), 12.1 µg m−3 (29.9 %), and 11.6 µg m−3 (29.7 %), respectively. Moreover, the variation of the boundary layer height had a strong effect on the concentration level of both PM2.5 and ozone. The lee vortex and land–sea breeze, as well as the boundary layer development, were the key mechanisms in air pollutant accumulation and transport. As typhoons frequently occur around Taiwan during summer and fall, their effect on the island's air quality merits further research attention.

scholarly journals The Impact of Secondary Flow Systems on Air Pollution in the Area of São Paulo

1998 ◽  
Vol 37 (3) ◽  
pp. 269-287 ◽  
Author(s):  
I. Bischoff-Gauß ◽  
N. Kalthoff ◽  
F. Fiedler
Keyword(s):  
Boundary Layer ◽  
Atlantic Ocean ◽  
Coastal Area ◽  
Air Pollutants ◽  
Large Scale ◽  
Sea Breeze ◽  
Sao Paulo ◽  
Steep Slope ◽  
São Paulo ◽  
Free Atmosphere

Abstract The area between the Atlantic Ocean and São Paulo is highly polluted due to high emission rates at Cubatão, a city situated 15 km inland at a steep slope. It was expected that secondary circulations would develop caused by the land–sea contrast and strong orographic changes, which influence the transport and diffusion of air pollutants. In 1994–95, surface stations were operated and radiosonde ascents were performed to analyze the characteristic features of the land–sea-breeze circulation. The stations make evident a land–sea-breeze system that arrived in the suburbs of São Paulo in the early afternoon. The upslope winds favor the propagation of the sea breeze at the steep slope. During the measurement period, large-scale northwesterly winds prevailed that advected warm air from the plateau to the coastal area in the afternoon and resulted in a limitation of the boundary layer growth. The data were used to initialize a three-dimensional mesoscale model for calculation of the transport and deposition of SO2 emitted at Cubatão. The boundary layer height was found to be a limitation for vertical mixing of the air pollutants. However, a step between the coastal boundary layer and the boundary layer over the plateau causes SO2 to be vented into the free atmosphere at the slope and then transported toward the Atlantic Ocean with the large-scale northwesterly winds. Thus, over the coastal area, the SO2 concentrations in the free atmosphere were even higher than within the mixed layer. The deposition, summed up over a day, was calculated and found to be strongest at the slope and over the Atlantic Ocean.

Effect of sea breeze regime on aerosol optical properties over the city of Rome, Italy.

2020 ◽  
Author(s):  
Annalisa Di Bernardino ◽  
Anna Maria Iannarelli ◽  
Stefano Casadio ◽  
Gabriele Mevi ◽  
Monica Campanelli ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Optical Properties ◽  
Air Quality ◽  
Sea Breeze ◽  
Coastal Areas ◽  
Horizontal Wind ◽  
Tyrrhenian Sea ◽  
Depth Analysis ◽  
The Impact ◽  
The City

<p>Mesoscale meteorological phenomena, such as sea-land breeze regime, strongly impact meteorological conditions of coastal areas, affecting wind intensity, moisture, heat and momentum fluxes and polluted air masses dispersion. This effect must be considered in order to correct design urban spaces, predict the possible influence of land use change on air pollution and climate change and, consequently, improve the quality of life and urban comfort.</p><p>In recent years, it has been shown that the breeze regime does not only affect microclimatic conditions but also air quality in coastal areas, because of the mixing of different types of aerosols and condensable gases. Moreover, the advection of marine, colder and more humid air leads to the decrease of the boundary layer height and, consequently, to the increase of the surface concentration of locally emitted pollutants, that are trapped within the boundary layer itself.</p><p>The effect of breeze regime is particularly interesting in coastal cities, where the sea breeze entails large modification of physical, optical, chemical, and hygroscopic properties of the urban aerosol.</p><p>In this work, we developed an approach to determine the breeze effect on aerosol in correspondence of the BAQUNIN [1] Super-site urban location, in the centre of Rome, Italy. The city is about 28 km far from the Tyrrhenian coast and is often exposed to sea-breeze circulation and to extreme aerosol events [2] [3].</p><p>In-situ measurements obtained from different remote sensing instruments are used: (i) vertical profile of horizontal wind velocity and direction by means of SODAR wind profiler; (ii) moisture, air temperature and wind speed from ground-based meteorological station; (iii) aerosol optical depth (AOD), height and evolution of the Boundary Layer from Raman and elastic LIDAR; (iv) precipitable water, AOD, Ångström exponent (AE) and single-scattering albedo (SSA) from sun-photometer CIMEL [4], (v) AOD, AE and SSA from POM 01 L Prede sun-sky radiometer [5][6], (vi) superficial NO<sub>2</sub> and formaldehyde amounts from PANDORA spectrometer [7], (vii) particulate matter (PM<sub>2.5 </sub>and PM<sub>10</sub>) concentrations from ground-based air quality station.</p><p>The investigation is focused on several days, during summer of 2019, characterized by anemological breeze regime conditions.</p><p>In this study, we present preliminary results aimed to the in-depth analysis of the effects of the breeze regime on the optical properties of aerosols in coastal, urban environment and the impact of the aerosol vertical stratification on ground-level PM concentrations.</p><p> </p><p>References:</p><p>[1] BAQUNIN Boundary-layer Air Quality-analysis Using Network of Instruments, www.baqunin.eu</p><p>[2] Petenko I. et al. (2011) “Local circulation diurnal patterns and their relationship with large-scale flows in a coastal area of the Tyrrhenian sea”, Boundary-Layer Meteorology, 139:353-366.</p><p>[3] Ciardini V. et al. (2012) “Seasonal variability of tropospheric aerosols in Rome”, Atmospheric Research, 118:205-214.</p><p>[4] AERONET, https://aeronet.gsfc.nasa.gov/new_web/index.html</p><p>[5] EUROSKYRAD http://www.euroskyrad.net/</p><p>[6] Campanelli M. et al. (2019) “Aerosol optical characteristics in the urban area of Rome, Italy, and their impact on the UV index”, Atmospheric Measurement Techniques Discussion.</p><p>[7] PGN, https://www.pandonia-global-network.org/</p>

scholarly journals Emission level of air pollutants during 2019 pre-haze, haze, and post-haze episodes in Kuala Lumpur and Putrajaya

2021 ◽  
Vol 4 (2) ◽  
pp. 137
Author(s):  
Safari Zainal ◽  
Nurfatiha Mursyida Zamre ◽  
Md. Firoz Khan
Keyword(s):  
Carbon Monoxide ◽  
Air Quality ◽  
Wind Direction ◽  
Air Pollutants ◽  
Power Plants ◽  
Meteorological Factors ◽  
Ambient Air ◽  
Kuala Lumpur ◽  
North East ◽  
East Malaysia

Nowadays, due to population growth and industrialisation, air quality in Malaysia is becoming a critical threat. Air pollution has become a serious issue due to its impacts on humans, animals, and the environment. Malaysia experienced air quality deterioration in 2019 when the episodes of haze happened from July to September. It was due to the local and transboundary sources such as vehicles, factories, power plants, and biomass burning from Sumatra. This study aims to differentiate the level of the potential air pollutants, examine the influence of meteorological factors on the potential air pollutants and determine the local and transboundary impact on the potential air pollutants during episodes of pre-haze, haze, and post-haze in Kuala Lumpur and Putrajaya in 2019. Secondary physical and data on meteorology were obtained from the continuous ambient air quality monitoring (CAQM) stations by the Malaysian Department of Environment (DOE). The data obtained from CAQM were physical: particulate matters (PM2.5 & PM10), carbon monoxide (CO), nitrogen dioxide (NO2), sulphur dioxide (SO2), and level ozone (O3); as well as meteorological: temperature (T), relative humidity (RH), wind speed (WS) and wind direction (WDir). Overall, the particulate matter (PM2.5, PM10) and carbon monoxide which are the pollutants that involve the formation of haze in Kuala Lumpur and Putrajaya are higher during haze episodes compared to pre-haze and post-haze episodes while the other pollutants (NO2, SO2, O3) are fluctuated throughout the entire episode due to its sources and the influence of meteorological factors. The backward trajectory indicated that the air pollutants are influenced by wind direction from South West Malaysia (SWM) and North East Malaysia (NEM) throughout the entire year.

scholarly journals Factors controlling surface ozone in the Seoul Metropolitan Area during the KORUS-AQ campaign

Elem Sci Anth ◽  
2020 ◽  
Vol 8 ◽  
Author(s):  
Heejeong Kim ◽  
Junsu Gil ◽  
Meehye Lee ◽  
Jinsang Jung ◽  
Andrew Whitehill ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Metropolitan Area ◽  
Production Efficiency ◽  
Surface Ozone ◽  
Sea Breeze ◽  
Photochemical Activity ◽  
Local Circulation ◽  
Boundary Layer Height ◽  
Seoul Metropolitan Area

To understand the characteristics of air quality in the Seoul Metropolitan Area, intensive measurements were conducted under the Korea-United States Air Quality (KORUS-AQ) campaign. Trace gases such as O3, NOx, NOy, SO2, CO, and volatile organic compounds (VOCs), photochemical byproducts such as H2O2 and HCHO, aerosol species, and meteorological variables including planetary boundary layer height were simultaneously measured at Olympic Park in Seoul. During the measurement period, high O3 episodes that exceeded the 90 ppbv hourly maximum occurred on 14 days under four distinct synoptic meteorological conditions. Furthermore, local circulation such as land–sea breeze and diurnal evolution of the boundary layer were crucial in determining the concentrations of precursor gases, including NOx and VOC as well as O3. During such episodes, the nighttime NOx and VOC and daytime UV levels were higher compared to non-episode days. The overall precursor levels and photochemical activity were represented fairly well by variations in the HCHO, which peaked in the morning during the high O3 episodes. This study revealed that toluene was the most abundant VOC in Seoul, and its concentration increased greatly with NOx due to the large local influence under stagnant conditions. When O3 was highly elevated concurrently with PM2.5 under dominant westerlies, NOx and VOCs were relatively lower and CO was noticeably higher than in other episodes. Additionally, the O3 production efficiency was the highest due to a low NOx with the highest NOz/NOy ratio among the four episodes. When westerlies were dominant in transport-south episode, the nighttime concentration of O3 remained as high as 40~50 ppbv due to the minimum level of NOx titration. Overall, the Seoul Metropolitan Area is at NOx-saturated and VOC-limited conditions, which was diagnosed by indicator species and VOC/NOx ratios.

scholarly journals Characteristics of Atmospheric Boundary Layer Structure during PM2.5 and Ozone Pollution Events in Wuhan, China

Atmosphere ◽  
2018 ◽  
Vol 9 (9) ◽  
pp. 359 ◽  
Author(s):  
Yassin Mbululo ◽  
Jun Qin ◽  
Jun Hong ◽  
Zhengxuan Yuan
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Atmospheric Boundary Layer ◽  
Air Pollutants ◽  
Inversion Layer ◽  
Ozone Pollution ◽  
Backward Trajectories ◽  
Investigation Period ◽  
Calm Wind ◽  
Pollution Events

In this study, we investigated six air pollutants from 21 monitoring stations scattered throughout Wuhan city by analyzing meteorological variables in the atmospheric boundary layer (ABL) and air mass backward trajectories from HYSPLIT during the pollution events. Together with this, ground meteorological variables were also used throughout the investigation period: 1 December 2015 to 30 November 2016. Analysis results during this period show that the city was polluted in winter by PM2.5 (particulate matter with aerodynamics of less than 2.5 microns) and in summer by ozone (O3). The most polluted day during the investigation period was 25 December 2015 with an air quality index (AQI) of 330 which indicates ‘severe pollution’, while the cleanest day was 26 August 2016 with an AQI of 27 indicating ‘excellent’ air quality. The average concentration of PM2.5 (O3) on the most polluted day was 265.04 (135.82) µg/m3 and 9.10 (86.40) µg/m3 on the cleanest day. Moreover, the percentage of days which exceeded the daily average limit of NO2, PM10, PM2.5, and O3 for the whole year was 2.46%, 14.48%, 23.50%, and 39.07%, respectively, while SO2 and CO were found to be below the set daily limit. The analysis of ABL during PM2.5 pollution events showed the existence of a strong inversion layer, low relative humidity, and calm wind. These observed conditions are not favorable for horizontal and vertical dispersion of air pollutants and therefore result in pollutant accumulation. Likewise, ozone pollution events were accompanied by extended sunshine hours, high temperature, a calm wind, a strongly suspended inversion layer, and zero recorded rainfall. These general characteristics are favorable for photochemical production of ozone and accumulation of pollutants. Apart from the conditions of ABL, the results from backward trajectories suggest trans-boundary movement of air masses to be one of the important factors which determines the air quality of Wuhan.

scholarly journals Role of Atmospheric Boundary Layer (ABL) Height and Ventilation Coefficient on Urban Air Quality- A study based on Observations and NWP Model

2019 ◽  
Vol 2 (3) ◽  
Author(s):  
Aditi Singh
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Atmospheric Boundary Layer ◽  
Air Pollutants ◽  
Weather Prediction ◽  
Urban Region ◽  
Maximum Height ◽  
Nwp Model ◽  
Ventilation Coefficient

Air pollution is an issue of great concern in any urban region due to its serious health implications. The capital of India, New Delhi continues to be in the list of most polluted cities since 2014. The air quality of any region depends on the ability of dispersion of air pollutants. The height or depth of the atmospheric boundary layer (ABL) is one measure of dispersion of air pollutants. Ventilation coefficient is another crucial parameter in determining the air quality of any region. Both of these parameters are obtained over Delhi from the operational global numerical weather prediction (NWP) model of National Centre for Medium Range Weather forecasting (NCMRWF) known as NCMRWF Unified Model (NCUM). The height of ABL over Delhi, is also obtained from radiosonde observations using the parcel method. A good agreement is found between the observed and predicted values of ABL height. The maximum height of ABL is obtained during summer season and minimum is obtained in winter season. High values of air pollutants are found when the values of ABL height and ventilation coefficient are low. 

scholarly journals Assessment of the contribution of TEX air pollutants from Nigeria’s petroleum refineries to the ambient air quality: Part II

2021 ◽  
Vol 8 (1) ◽  
pp. 1947007
Author(s):  
Ebenezer Leke Odekanle ◽  
Chinchong Blessing Bakut ◽  
Abiodun Paul Olalekan ◽  
Roseline Oluwaseun Ogundokun ◽  
Charity O. Aremu ◽  
...  
Keyword(s):  
Air Quality ◽  
Air Pollutants ◽  
Ambient Air ◽  
Ambient Air Quality ◽  
Petroleum Refineries

scholarly journals Spatial and Temporal Characteristics of Environmental Air Quality and Its Relationship with Seasonal Climatic Conditions in Eastern China during 2015–2018

2021 ◽  
Vol 18 (9) ◽  
pp. 4524
Author(s):  
Zhiyuan Wang ◽  
Xiaoyi Shi ◽  
Chunhua Pan ◽  
Sisi Wang
Keyword(s):  
Particulate Matter ◽  
Air Quality ◽  
Air Pollutants ◽  
Large Scale ◽  
Asian Summer Monsoon ◽  
Eastern China ◽  
Climatic Conditions ◽  
Uniform Structure ◽  
Concentration Limit ◽  
Environmental Air

Exploring the relationship between environmental air quality (EAQ) and climatic conditions on a large scale can help better understand the main distribution characteristics and the mechanisms of EAQ in China, which is significant for the implementation of policies of joint prevention and control of regional air pollution. In this study, we used the concentrations of six conventional air pollutants, i.e., carbon monoxide (CO), sulfur dioxide (SO2), nitrogen dioxide (NO2), fine particulate matter (PM2.5), coarse particulate matter (PM10), and ozone (O3), derived from about 1300 monitoring sites in eastern China (EC) from January 2015 to December 2018. Exploiting the grading concentration limit (GB3095-2012) of various pollutants in China, we also calculated the monthly average air quality index (AQI) in EC. The results show that, generally, the EAQ has improved in all seasons in EC from 2015 to 2018. In particular, the concentrations of conventional air pollutants, such as CO, SO2, and NO2, have been decreasing year by year. However, the concentrations of particulate matter, such as PM2.5 and PM10, have changed little, and the O3 concentration increased from 2015 to 2018. Empirical mode decomposition (EOF) was used to analyze the major patterns of AQI in EC. The first mode (EOF1) was characterized by a uniform structure in AQI over EC. These phenomena are due to the precipitation variability associated with the East Asian summer monsoon (EASM), referred to as the “summer–winter” pattern. The second EOF mode (EOF2) showed that the AQI over EC is a north–south dipole pattern, which is bound by the Qinling Mountains and Huaihe River (about 35° N). The EOF2 is mainly caused by seasonal variations of the mixed concentration of PM2.5 and O3. Associated with EOF2, the Mongolia–Siberian High influences the AQI variation over northern EC by dominating the low-level winds (10 m and 850 hPa) in autumn and winter, and precipitation affects the AQI variation over southern EC in spring and summer.

Sign in / Sign up

Export Citation Format

Share Document