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Absorption Angstrom exponent (AAE, 470/950 nm) versus scattering Angstrom exponent (SAE, 450/635 nm), color coded by the aerosol absorption coefficient at 880 nm. Dry daily average values are shown (February 2014-June 2018). The classification by aerosol type is based on Cazorla et al. (2013).
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In 2014, Pha Din (1466 m a.s.l.) was established as a Global Atmosphere Watch (GAW) regional station for aerosol and
trace gas measurements in northwestern Vietnam. This study presents a five-year climatology of aerosol optical properties
derived from nephelometer and aethalometer measurements and a comparison with ground-based remote sensing
measu...
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Context 1
... CO emissions Supplementary Information). In contrast, the lower values in the summer months largely coincide with the SE Asian summer monsoon with more rain and generally more humid conditions. During the time period covered so far by the measurements at Pha Din, a decrease in peak intensity for all parameters is observed between 2014 and 2018. Fig. 3 shows a classification of aerosol types based on AAE and SAE (Cazorla et al., 2013). AAE dry reaches 1.6-2.0 during BB periods, a typical value for BB dominated aerosol in northern Indochina ( Wang et al., 2015). SAE dry is > 1.5, pointing to a dominant contribution of accumulation mode particles to light scattering, as is expected for ...
Context 2
... during BB periods, a typical value for BB dominated aerosol in northern Indochina ( Wang et al., 2015). SAE dry is > 1.5, pointing to a dominant contribution of accumulation mode particles to light scattering, as is expected for BB aerosols, and does not indicate a significant influence of coarse mode dust. According to the classification used in Fig. 3, the aerosol detected during high BB episodes is thus characterized as "OC dominated", while for the rest of the year, the major fraction of the data is classified as "EC/OC ...
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Five mainland SEA countries (Cambodia, Laos, Myanmar, Vietnam, and Thailand) are threatened by climate change. Here, the latest 18 Coupled Model Intercomparison Project Phase 6 (CMIP6) is employed to examine future climate change in this region under two SSP-RCP (shared socioeconomic pathway-representative concentration pathway) scenarios (SSP2-4.5...
Citations
... Here we report on long-term observations of CO, ozone (O3) and carbonaceous greenhouse gases (GHG) including carbon dioxide (CO2) and methane (CH4) based on measurements performed at the regional Global Atmosphere Watch (GAW) station Pha Din (PDI) in Northwestern Vietnam. Our study on trace gases complements previous studies at PDI, which focused on aerosol optical properties (Bukowiecki et al., 2019) and carbonaceous aerosol composition (Nguyen et al., 2021). ...
... In 2014, PDI was accepted as a regional station of the World Meteorological Organization's (WMO) Global Atmosphere Watch (GAW) programme. The station, described in detail in Bukowiecki et al. (2019), is located 360 km northwest of Hanoi, 200 km south of the border with China, and 120 km east of the border with Laos (see Figure 1). The observation site is located on the top of a hill (see Figure 2) about 1 km north of the Pha Din mountain pass, which connects Son-La city (to the southeast) and Dien-Bien-Phu city (to the west) via national highway AH13. ...
... Trace gas observations are publically available at the World Data Centre for Greenhouse (CO2, CH4, CO; https://gaw.kishou.go.jp) and the World Data Centre for Reactive Gases (O3; https://www.gaw-wdcrg.org/). Details on the in-situ aerosol observations can be found in Bukowiecki et al. (2019). Details on quartz filter collection for chemical analysis of carbonaceous aerosol can be found in Nguyen et al. (2021). ...
Biomass burning (BB), including forest wildfires and agricultural waste burning, is a major source of atmospheric trace gases and aerosols that are harmful for human health and alter the Earth's radiative balance. Here, we study the influence of BB on trace gas levels and air quality on the Indochinese Peninsula in Southeast Asia, where the dry season from mid-December until mid-April leads to regularly recurring large-scale BB until the onset of the Asian summer monsoon. Since 2014, trace gases and air quality parameters (carbon dioxide (CO2), methane (CH4), carbon monoxide (CO), and ozone (O3)), and aerosol optical properties have been continuously monitored in-situ at the regional Global Atmosphere Watch (GAW) station Pha Din (PDI) in rural Northwestern Vietnam. The station is well suited to study the large-scale fires on the Indochinese Peninsula, as emission plumes are frequently transported towards the site. Our investigations indicates that the annually recurrent large-scale BB leads to CO mixing ratios at PDI that exceed 1000 ppb (24-hour means) typically during the February to April dry season. Instead, mixing ratios are well below 100 ppb are observed in summer, when precipitation reaches a maximum. Further, we compare CO mixing ratios from two atmospheric transport and chemistry simulations (Copernicus Atmospheric Monitoring Service (CAMS) global reanalysis and dedicated FLEXPART backward simulations) to the observations at PDI. Although, the simulations tend to overestimate CO values during the periods when highest CO mixing ratios are observed, they in general confirm the large impact of BB on observations at PDI and indicate that mostly very fresh BB emissions are sampled in the most prominent plumes (age 24 h to 72 h).
... In many countries like China, Spain, Italy, USA, India, Korea [18], Indonesia [19], and France [20] the reduction in air pollutants was observed during this pandemic. The PM2.5, PM10 [19], NO2, CO all air pollutants are mostly emitted from the fossil fuels based oil used in automobiles and from industrial activities. ...
... In many countries like China, Spain, Italy, USA, India, Korea [18], Indonesia [19], and France [20] the reduction in air pollutants was observed during this pandemic. The PM2.5, PM10 [19], NO2, CO all air pollutants are mostly emitted from the fossil fuels based oil used in automobiles and from industrial activities. The enforced lockdown in many countries has clogged all these activities for some time period. ...
The ongoing COVID-19 pandemic affected everyone’s life in every aspect. World Health Organization declared it as global emergency in March 2020 which leads to halt all the human activity around the world. While this pandemic was hazardous for human beings the nature was nourishing itself and seems to be on reset as the Pollution decreased due to this pandemic. In countries like China, Italy, USA and many more which initiated the lockdown in their countries to avoid the spread of this deadly virus has shown the reduction of air pollution. The emission of air pollutants were reduced due the lockdowns in many countries. In the paper different types of environmental pollution, their reasons and effects on nature are discussed and also the impact of COVID-19 pandemic on environment is discussed.
... The north of Vietnam located in the northern Southeast Asia region largely suffered from BB plumes originated from forest fires and burning of agricultural residuals (Gautam et al. 2013). For example, the BB plumes from Myanmar, Laos, Cambodia, and Northern Thailand were diffused and transported to the northwest mountainous area in the north of Vietnam (Bukowiecki et al. 2019;Nguyen et al. 2021). Hanoi City and Son La Province are the two fast-developing urban areas located in the north of Vietnam exposed to elevated concentrations of air pollutants emitted from not only BB activities but also intense anthropogenic activities, which has led to immense human health effects. ...
... Hanoi City and Son La Province are the two fast-developing urban areas located in the north of Vietnam exposed to elevated concentrations of air pollutants emitted from not only BB activities but also intense anthropogenic activities, which has led to immense human health effects. The investigated areas exposed to the major local aerosol sources included emissions-related automobiles, industry activities, secondary emission, road/construction, fossil fuels, and biomass burning (Gatari et al. 2005;Oanh et al. 2009;Cohen et al. 2010;Bukowiecki et al. 2019;Bui et al. 2020;Nghiem et al. 2020). In addition, the north of Vietnam also experienced transboundary air pollutants (Hien et al. 2005(Hien et al. , 2011 with the air masses arriving from the southwest regions being less polluted than those coming from the north and northeast regions (Hien et al. 2004). ...
... Nghia Do AERONET station is situated in a populous urban area in Hanoi with diverse anthropogenic emission sources such as traffic, industrial, construction, and waste incineration. Meanwhile, Son La AERONET station is situated on the hill surrounded by mountainous vegetated areas of Son La City which suffered from not only anthropogenic emission sources (Bukowiecki et al. 2019) but also biomass burning sources such as forest wildfires and local people's habit of burning wood for energy supply Popovicheva et al. 2016). ...
The spatiotemporal distribution and characterization of aerosol optical properties in the north of Vietnam were investigated extensively using the long-term measurements obtained from Moderate Resolution Imaging Spectroradiometer (MODIS) (from 2010 to 2019) and two Aerosol Robotic Network (AERONET) stations (Nghia Do, Hanoi City, from 2010 to 2019 and Son La from 2012 to 2019) located in fast-developing urban areas. This study also analyzed the tendency of AOD over different wavelengths as well as the influences of meteorological parameters and boundary layer height (BLH) on AOD and Ångström exponent (AE). The annual mean AOD500 at Nghia Do and Son La stations were 0.81 and 0.78, respectively. Our results revealed the existence of particles emitted from anthropogenic activities in Hanoi and Son La with the dominance of fine particles (more than 90% of the AE440–870 were larger than 1). Besides, a high percentage of AE440–870 larger than or approximately 1.5 during the dry and transition months in Son La indicated the existence of biomass-burning aerosol particles due to forest fires and burning of agriculture residuals. The classification results for aerosol types showed the presence of both biomass burning and urban/industrial aerosol types at Nghia Do and Son La sites. Among the investigated meteorological parameters, surface solar radiation expressed a significant correlation with AE440–870 in all three seasons at the two sites due to the secondary formation of fine particles induced by the high solar radiation condition. The impacts of meteorological parameters and BLH on AOD were not observed simultaneously during three seasons at Nghia Do and Son La stations.
... Thus, levoglucosan and its isomers are used as specific chemical markers to identify biomass-burning-derived emissions and help in source apportionment approaches. Such compounds have been used in studies around the world: in Europe [84,[107][108][109][110], North and South America [111][112][113], as well as Asia [114][115][116][117][118][119]. ...
The adverse effects of atmospheric particulate matter (PM) on health and ecosystems, as well as on meteorology and climate change, are well known to the scientific community. It is therefore undeniable that a good understanding of the sources of PM is crucial for effective control of emissions and to protect public health. One of the major contributions to atmospheric PM is biomass burning, a practice used both in agriculture and home heating, which can be traced and identified by analyzing sugars emitted from the combustion of cellulose and hemicellulose that make up biomass. In this review comparing almost 200 selected articles, we highlight the most recent studies that broaden such category of tracers, covering research publications on residential wood combustions, open-fire or combustion chamber burnings and ambient PM in different regions of Asia, America and Europe. The purpose of the present work is to collect data in the literature that indicate a direct correspondence between biomass burning and saccharides emitted into the atmosphere with regard to distinguishing common sugars attributed to biomass burning from those that have co-causes of issue. In this paper, we provide a list of 24 compounds, including those most commonly recognized as biomass burning tracers (i.e., levoglucosan, mannosan and galactosan), from which it emerges that monosaccharide anhydrides, sugar alcohols and primary sugars have been widely reported as organic tracers for biomass combustion, although it has also been shown that emissions of these compounds depend not only on combustion characteristics and equipment but also on fuel type, combustion quality and weather conditions. Although it appears that it is currently not possible to define a single compound as a universal indicator of biomass combustion, this review provides a valuable tool for the collection of information in the literature and identifies analytes that can lead to the determination of patterns for the distribution between PM generated by biomass combustion.
... Pani et al., 2019b) in Thailand and Hanoi (10e15;Popovicheva et al., 2017) in Vietnam, indicating the significant influence of OC on air quality. Solar light absorption by BB-derived BC and BrC over nearsource and downwind locations is a critical issue over northern PSEA with respect to regional climate change including the complex aerosol-cloud-radiation interaction processes Tsay et al., 2016;Pani et al., 2016aPani et al., , 2016bPani et al., , 2018Bukowiecki et al., 2019;Dong et al., 2019). ...
Light-absorbing organic carbon (or brown carbon, BrC) has been recognized as a critical driver in regional-to-global climate change on account of its significant contribution to light absorption. BrC sources vary from primary combustion processes (burning of biomass, biofuel, and fossil fuel) to secondary formation in the atmosphere. This paper investigated the light-absorbing properties of BrC such as site-specific mass absorption cross-section (MACBrC), absorption Ångström exponent (AAEBrC), and the absorbing component of the refractive index (kBrC) by using light absorption measurements from a 7-wavelength aethalometer over an urban environment of Chiang Mai, Thailand in northern peninsular Southeast Asia (PSEA), from March to April 2016. The contribution of BrC to total aerosol absorption (mean ± SD) was 46 ± 9%, 29 ± 7%, 24 ± 6%, 20 ± 4%, and 15 ± 3% at 370, 470, 520, 590, and 660 nm, respectively, highlighting the significant influence of BrC absorption on the radiative imbalance over northern PSEA. Strong and significant associations between BrC light absorption and biomass-burning (BB) organic tracers highlighted the influence of primary BB emissions. The median MACBrC and kBrC values at 370 nm were 2.4 m2 g−1 and 0.12, respectively. The fractional contribution of solar radiation absorbed by BrC relative to BC (mean ± SD) in the 370–950 nm range was estimated to be 34 ± 7%, which can significantly influence the regional radiation budget and consequently atmospheric photochemistry. This study provides valuable information to understand BrC absorption over northern PSEA and can be used in model simulations to reassess the regional climatic impact with greater accuracy.
... Furthermore, BB generally emits large amounts of particulate matter (PM), black carbon (BC), and trace gases including carbon monoxide (CO), carbon dioxide (CO 2 ), methane (CH 4 ), and nitrous oxide (N 2 O) into the atmosphere (Akagi et al., 2011;Ciais et al., 2013;Tian et al., 2016;Andreae, 2019;Pani et al., 2019aPani et al., , 2019bPani et al., , 2020Thepnuan et al., 2019). The impact of PSEA BB emissions on the local and regional-scale normally persists for weeks to months by influencing air quality, atmospheric chemistry, and radiative balance (Lin et al., , 2014Wang et al., 2015;Tsay et al., 2016;Pani et al., 2016aPani et al., , 2018Punsompong and Chantara, 2018;Bukowiecki et al., 2019). Moreover, PSEA BB-derived air pollutants can be advected over long distances downwind and contribute to transboundary atmospheric pollution (e.g., Lin et al., 2013;Pani et al., 2016b;Lolli et al., 2019;Liang et al., 2019;Huang et al., 2020). ...
Biomass-burning (BB) related air pollution is a prime concern in several regions of the world including Southeast Asia. This study aimed to identify and apportion the BB types (agricultural, forest, and grassland) and assess the transport of BB-derived PM2.5 which influences the air quality index (AQI) of three major regions (i.e., central, north, and northeast) in Thailand by integrating satellite fire products, air-mass trajectories, ground-based measurements, statistical approaches, and modeling tools. We accounted for the transport time of PM2.5 from source to monitoring stations by grouping the BB type with air-mass trajectory timestamps. Forest fire predominated over the north (73%) and northeast (48%) whereas agricultural burning predominated over the central (52%) region. Grassland burning was most influential in the central region (16%) followed by the northeast (11%) and north (5%) regions in Thailand. Annual PM2.5 exposure amounted to very-unhealthy to hazardous PM2.5-AQI levels for about 79% of the Thailand population. PM2.5-AQI levels over Thailand were mainly governed by transboundary BB influence (67%) whereas the local contribution was about 33%. Excess numbers of premature deaths due to PM2.5 exposure totaled 18,003, and were associated with stroke burden (53%), ischemic heart disease (30%), lung cancer (12%), and chronic obstructive pulmonary disease (5%), based on public-health data from 2016. The spatial distribution results of excess mortality showed the largest burden in the central region (44%) followed by the northeast (29%), north (18%), and south (9%). Our study results are useful for shaping effective control strategies of open burning management in Thailand and other nearby countries in peninsular Southeast Asia.
... Aerosols are basically fine liquid and solid suspensions present in the atmosphere. [4] The main cause of these aerosols over SEA is the gases like Sulfate, Nitrate and Ammonium emitted by the industries, volcanic ashes and burning of biological fuels, pre-monsoon forest and agricultural fires are also some of the main causes. So, by analyzing AOD we can detect the variations in the concentration level of pollutants mainly in the lower troposphere region. ...
... The Pha Din Global Atmosphere Watch (GAW) regional monitoring station, PDI, is located in the north of the Indochina Peninsula, where there are BB activities during pre-monsoon season from February to April (Lin et al., 2013). Continuous observations of aerosol optical properties and greenhouse gases have been implemented at PDI since early 2014, and aerosol 60 optical properties have been previously discussed by Bukowiecki et al. (2019). However, the source apportionment was only based on light-absorbing carbon and levoglucosan concentrations. ...
... So far, very few studies Popovicheva et al., 2016;Popovicheva et al., 2017;Pham et al., 2019) investigated the organic chemical composition of aerosol samples collected in Northwestern Vietnam during BB events in detail. We complement the analysis by Bukowiecki et al. (2019) and present results from the chemical analysis of PM2.5 samples and trace gas measurements collected during the BB season in 65 2015 at PDI. We discuss the daily variations of bulk carbonaceous components (OC, EC), and provide a detailed chemical analysis of organic aerosol constituents, including anhydrous sugars, methoxyphenols, n-alkanes, fatty acids, PAHs, o-PAHs, and nitro-phenols and add valuable data to the available body of literature. ...
... Data were collected at the PDI site (1466 m a.s.l., 21.573°N 103.516°E), a meteorological station of the Vietnam Meteorological and Hydrological Administration (VNMHA) and a regional station of the World Meteorological Organization's (WMO) Global Atmosphere Watch (GAW) program since 2014. Aside of instrumentation to collect meteorological data, the 75 site is equipped with continuous in-situ observations of aerosol optical properties and trace gases, as described in Bukowiecki et al. (2019). The station is located in Dien Bien Province, which is 360 km northwest of Hanoi, 200 km south of the border with China, and 120 km east of the border with Laos ( Figure 1). ...
We investigated concentrations of organic carbon (OC), elemental carbon (EC) and a wide range of particle-bound organic compounds in daily sampled PM2.5 at the remote Pha Din (PDI) – Global Atmosphere Watch (GAW) monitoring station in Northwestern Vietnam during an intense 3-week sampling campaign from 23rd March to 12th April 2015. The site is known to receive trans-regional air masses during large-scale biomass burning episodes, but OC composition studies are missing in the scientific literature. We quantified 51 organic compounds simultaneously by in-situ derivatization thermal desorption gas chromatography time-of-flight mass spectrometry (IDTD-GC-TOFMS). Anhydrosugars, methoxyphenols, n-alkanes, fatty acids, polycyclic aromatic hydrocarbons, oxygenated polycyclic aromatic hydrocarbons, nitrophenols as well as OC were used in a hierarchical cluster analysis highlighting distinctive patterns for periods under low, medium and high biomass burning (BB) influence. The highest particle phase concentration of the typical primary organic aerosol (POA) and possible secondary organic aerosol (SOA) constituents, especially nitrophenols, were found on 5th and 6th April. We linked the trace gases CH4, CO2, CO, O3 mixing ratios to the statistical classification of BB events based on OA composition and found increased CO and O3 levels during medium and high BB influence. Likewise, a backward trajectory analysis indicates different source regions for the identified periods based on the OA cluster, with cleaner air masses arriving from northeast, i.e., mainland China and Yellow sea. The more polluted periods are characterized by trajectories from southwest, with more continental recirculation of the medium cluster, and more westerly advection for the high cluster. These findings highlight that BB activities in Northern Southeast Asia cannot only significantly enhance the regional organic aerosol loading, but also affect the carbonaceous PM2.5 constituents and the trace gases in northwestern Vietnam. The presented analysis adds valuable data on the carbonaceous and in particular OC chemical composition of PM2.5 in a region of scarce data availability.
... It is interesting to note that occasionally the rural stations as AMY (East Asia) and KOS (central Europe) have median and range values of σ ap similar to urban sites, despite being located in rural areas far from local sources. PDI and BKT, both mountain sites in South-East Asian tropical forests, exhibit large medians for both σ ap and σ sp compared to other forest/mountain sites due to recurrent impact by biomass burning (Bukowiecki et al., 2019). Similarly, biomass burning events related to anthropogenic emission from mainland China also affect via regional transport both LLN, another mountain site in South-East Asia, and AMY. Figure 5. Boxplot of hourly aerosol absorption (a) and scattering (b) coefficients at the SARGAN sites with sufficient annual coverage over the considered period (see summary Tables S1 and S2 for details). ...
Aerosol particles are essential constituents of the Earth's atmosphere, impacting the earth radiation balance directly by scattering and
absorbing solar radiation, and indirectly by acting as cloud condensation
nuclei. In contrast to most greenhouse gases, aerosol particles have short
atmospheric residence times, resulting in a highly heterogeneous distribution in space and time. There is a clear need to document this variability at
regional scale through observations involving, in particular, the in situ
near-surface segment of the atmospheric observation system. This paper will provide the widest effort so far to document variability of climate-relevant
in situ aerosol properties (namely wavelength dependent particle light
scattering and absorption coefficients, particle number concentration and
particle number size distribution) from all sites connected to the Global
Atmosphere Watch network. High-quality data from almost 90 stations worldwide have been collected and controlled for quality and are reported
for a reference year in 2017, providing a very extended and robust view of
the variability of these variables worldwide. The range of variability
observed worldwide for light scattering and absorption coefficients, single-scattering albedo, and particle number concentration are presented together with preliminary information on their long-term trends and comparison with
model simulation for the different stations. The scope of the present paper
is also to provide the necessary suite of information, including data provision procedures, quality control and analysis, data policy, and usage of
the ground-based aerosol measurement network. It delivers to users of the World Data Centre on Aerosol, the required confidence in data products in
the form of a fully characterized value chain, including uncertainty estimation and requirements for contributing to the global climate
monitoring system.
... It is interesting to note that occasionally the rural stations as AMY (East Asia) and KOS (central Europe) have median and range values of σ ap similar to urban sites, despite being located in rural areas far from local sources. PDI and BKT, both mountain sites in South-East Asian tropical forests, exhibit large medians for both σ ap and σ sp compared to other forest/mountain sites due to recurrent impact by biomass burning (Bukowiecki et al., 2019). Similarly, biomass burning events related to anthropogenic emission from mainland China also affect via regional transport both LLN, another mountain site in South-East Asia, and AMY. Figure 5. Boxplot of hourly aerosol absorption (a) and scattering (b) coefficients at the SARGAN sites with sufficient annual coverage over the considered period (see summary Tables S1 and S2 for details). ...
