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A case study on the effect of contaminated inlet tubes on the accuracy of mid-cost optical particle counters for the ambient air monitoring of fine particles 进气管污染对用于环境空气细颗粒监测的中等成本光学颗粒计数器精度影响的案例研究
IF 1.1 Q4 METEOROLOGY & ATMOSPHERIC SCIENCES Pub Date : 2024-11-05 DOI: 10.1007/s44273-024-00045-w
Trieu-Vuong Dinh, Byeong-Gyu Park, Sang-Woo Lee, Da-Hyun Baek, In-Young Choi, Jo-Chun Kim

This study investigates the impact of the long-term use of inlet-heated tubes on the performance of mid-cost optical particle counters (OPCs) for ambient air monitoring of fine particles (PM2.5). Two OPCs, equipped with inlet-heated tubes, were deployed over a 6-month period, with a beta attenuation monitor (BAM) serving as the reference device. The performance of the OPCs using the same inlet tubes for the first 3 months was compared to their performance after the frequent replacement of clean tubes during the final 3 months. The correlation coefficients (r2) for the 1 h and 24 h average PM2.5 concentrations between the OPCs and the BAM were lower with long-term contaminated tubes (0.82 < r2 < 0.93) compared to clean tubes (r2 > 0.93). The relative mean errors and biases significantly increased over time with contaminated tubes. Temperature, humidity, precipitation, and wind speed were found to have an insignificant effect (r2 < 0.1) on the performance of the two OPCs with inlet-heated tubes over the 6-month period. The relative average PM2.5 error when using clean tubes was less than 4%. These findings highlight the importance of inlet-heated tubes in improving OPC performance, particularly for mitigating humidity effects.

Graphical Abstract

本研究调查了长期使用入口加热管对用于环境空气细颗粒物(PM2.5)监测的中等成本光学颗粒物计数器(OPC)性能的影响。在为期 6 个月的时间里,部署了两台配有进气口加热管的光学粒子计数器,并用β衰减监测器(BAM)作为参照设备。将前 3 个月使用相同入口管道的 OPC 的性能与最后 3 个月频繁更换清洁管道后的性能进行了比较。与清洁管道(r2 >0.93)相比,长期污染管道(0.82 <r2 <0.93)与 OPC 和 BAM 之间 1 h 和 24 h PM2.5 平均浓度的相关系数(r2)较低。随着时间的推移,污染试管的相对平均误差和偏差明显增大。在 6 个月期间,温度、湿度、降水和风速对使用进气加热管的两种 OPC 的性能影响不大(r2 <0.1)。使用清洁管道时,PM2.5的相对平均误差小于4%。这些研究结果突出表明了进气口加热管在改善 OPC 性能方面的重要性,尤其是在减轻湿度影响方面。
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引用次数: 0
Characteristic of PM2.5 concentration and source apportionment during winter in Seosan, Korea 韩国瑞山冬季 PM2.5 浓度特征和来源分配
IF 1.1 Q4 METEOROLOGY & ATMOSPHERIC SCIENCES Pub Date : 2024-11-05 DOI: 10.1007/s44273-024-00044-x
Soo Ran Won, Kwangyul Lee, Mijung Song, Changhyuk Kim, Kyoung-Soon Jang, Ji Yi Lee

Seosan is a concentrated industrial complex in the midwestern region of Korea. A study was conducted from December 2020 to January 2021, measuring PM2.5 and chemical components in Seosan using online instruments every hour. The concentration of PM2.5 during the winter season was 31.4±17.8 μg/m3, exceeding the national ambient air quality standard of Korea. The mass fraction of organic matter, elemental carbon, three major ions, five minor ions, crustal elements, and trace elements in PM2.5 accounted for 24.5%, 4.36%, 32.0%, 2.82%, 4.11%, and 5.17% of the total PM2.5 mass concentration, respectively. Source identification was conducted using positive matrix factorization modeling, revealing eight sources of PM2.5: Secondary inorganic aerosol (SIA), vehicle exhaust, industry, coal combustion, biomass burning/incinerator, oil combustion, soil, and aged sea salt. Source contributions varied during high pollution episodes (HPE), with SIA dominating in HPE1 and soil and aged sea salt in HPE2. The potential source contribution function and conditional probability function were utilized to estimate the potential local and regional emission areas for the identified sources. In Seosan, vehicle exhaust and biomass burning/incinerator were primarily influenced by local sources. SIA, industry, and oil combustion sources were significantly affected by short-range transport from eastern China. Soil and aged sea salt, which exhibited high contributions during HPE2, were associated with long-range transport from Inner Mongolia. Coal combustion was attributed to both local sources, particularly large industrial complexes near Seosan, and long-range transport from Northeast China and Inner Mongolia.

Graphical Abstract

瑞山是韩国中西部地区的一个工业集中区。2020 年 12 月至 2021 年 1 月期间进行了一项研究,使用在线仪器每小时测量瑞山的 PM2.5 和化学成分。冬季的 PM2.5 浓度为 31.4±17.8 μg/m3,超过了韩国国家环境空气质量标准。PM2.5中有机物、碳元素、三种主要离子、五种次要离子、地壳元素和微量元素的质量分数分别占PM2.5总质量浓度的24.5%、4.36%、32.0%、2.82%、4.11%和5.17%。利用正矩阵因式分解模型进行了来源识别,发现了 PM2.5 的八个来源:二次无机气溶胶(SIA)、汽车尾气、工业、燃煤、生物质燃烧/焚化炉、石油燃烧、土壤和老化海盐。在高污染事件 (HPE) 期间,污染源贡献各不相同,HPE1 以二次无机气溶胶为主,HPE2 以土壤和老化海盐为主。利用潜在污染源贡献函数和条件概率函数估算了已识别污染源的潜在本地和区域排放区域。在瑞山,汽车尾气和生物质燃烧/焚化炉主要受本地污染源的影响。SIA、工业和石油燃烧源则主要受到来自中国东部的短程传输的影响。土壤和老化海盐在 HPE2 期间的贡献率较高,与来自内蒙古的长程飘移有关。燃煤既有本地来源,特别是瑞山附近的大型工业综合体,也有来自中国东北和内蒙古的长程飘移。
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引用次数: 0
Vertical profile measurements for ammonia in a Japanese deciduous forest using denuder sampling technique: ammonia emissions near the forest floor 利用脱墨取样器采样技术测量日本落叶林的氨垂直剖面:林底附近的氨排放情况
IF 1.1 Q4 METEOROLOGY & ATMOSPHERIC SCIENCES Pub Date : 2024-10-25 DOI: 10.1007/s44273-024-00042-z
Mao Xu, Ryota Matsumoto, Phuvasa Chanonmuang, Kazuhide Matsuda

Ammonia (NH3) has received considerable attention as a major reduced nitrogen. However, accurate estimates of the deposition amount are difficult due to its complex behavior characterized by bidirectional exchange between the atmosphere and the surface. We observed the vertical profile of NH3 concentration in a deciduous forest in Japan for 1 year to further advance the studies on NH3 bidirectional exchange in Asia, especially focusing on the process near the forest floor. The observation period lasted from September 29, 2020, to September 28, 2021, including leafy and leafless periods. Using the denuder sampling technique, we measured NH3 concentration in the forest at three heights (above the forest canopy, 30 m, and near the forest floor, 2 m and 0.2 m). NH3 concentrations tended to be highest at the top of the canopy (30 m). Focusing on the concentration near the forest floor, the concentrations at 0.2 m were frequently higher than those at 2 m regardless of the leafy and leafless period, thus suggesting NH3 emissions from the forest floor. NH3 concentration near the forest floor showed strong positive correlations with air temperature during the leafy period. The NH3 emissions from the forest floor during the leafy period were possibly due to the decomposition of leaf litter with increased air temperature. The decrease in leaf area index might induced the increase in NH3 concentration and emission. NH3 emission during the leafless period was also possibly dependent on the state of the deposition surface, apart from air temperature, relative humidity, and leaf area index.

Graphical Abstract

氨(NH3)作为一种主要的还原氮,受到了广泛关注。然而,由于其在大气和地表之间双向交换的复杂行为,很难准确估计其沉积量。我们对日本落叶林中的 NH3 浓度垂直剖面进行了为期一年的观测,以进一步推进亚洲 NH3 双向交换的研究,特别是对林地附近过程的研究。观测时间为 2020 年 9 月 29 日至 2021 年 9 月 28 日,包括落叶期和无叶期。我们使用脱墨取样器采样技术,测量了森林中三个高度(林冠上方 30 米、林底附近 2 米和 0.2 米)的 NH3 浓度。林冠顶部(30 米)的 NH3 浓度往往最高。从林地附近的浓度来看,无论在落叶期还是无叶期,0.2 米处的浓度经常高于 2 米处的浓度,这表明 NH3 是由林地排放的。在落叶期,林地附近的 NH3 浓度与气温呈很强的正相关。落叶期林地的 NH3 排放可能是由于气温升高导致落叶分解所致。叶面积指数的下降可能会导致 NH3 浓度和排放量的增加。除气温、相对湿度和叶面积指数外,无叶期的 NH3 排放也可能取决于沉积表面的状态。
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引用次数: 0
Assessment of vehicle exhaust PM emissions using high-resolution on-road measurements in Seoul, Korea 利用韩国首尔的高分辨率路面测量评估汽车尾气 PM 排放量
IF 1.1 Q4 METEOROLOGY & ATMOSPHERIC SCIENCES Pub Date : 2024-10-22 DOI: 10.1007/s44273-024-00043-y
Jihwan Son, Yeosook Kim, Heesun Lee, Minjeong Seo, Yuri Choi, JinA Park, Yongsuk Choi, Ju-Sung Park, Gangwoong Lee

In megacities, road traffic is a major source of particulate matter (PM), requiring a critical understanding of effective air pollution control. Despite existing methods to determine PM emission factors (EFs) of vehicles, accurate estimation of PM emissions under real driving conditions remains challenging. We aimed to assess the EFs of organic aerosol (OA) and equivalent black carbon (eBC) from vehicles through on-road measurements in Seoul, Korea, to understand real-world PM emissions. We used a mobile laboratory equipped with an aerosol mass spectrometer and an aethalometer to measure the composition of PM. On-road measurements were conducted in vehicle tunnels, urban roadways, and residential areas, and the characteristics of measurement points were compared and analyzed. Our results showed that concentrations of OA increased proportionally with the influence of vehicle exhaust, while oxidation states of the OA decreased. Mobile measurements revealed spatial heterogeneities in aerosols, highlighting distinct characteristics of fresh OA on vehicle roads and elevated oxidation state values in residential areas. Active nitrate formation near vehicles led to elevated NO3 concentrations on roads compared to residential areas. Our study shows that mobile PM measurements, including OA and eBC, are valuable for the direct evaluation of emission inventories. However, given that the calculated EFs may not be applicable to other cities due to differences in vehicle composition and traffic conditions, the development of city-specific EFs will be necessary in the future. Furthermore, it is recommended to integrate this methodology with conventional emission inventories to identify vehicle-type-specific emissions.

Graphical Abstract

在特大城市,道路交通是颗粒物(PM)的主要来源,需要对有效的空气污染控制有一个关键的了解。尽管现有方法可以确定车辆的可吸入颗粒物排放系数(EFs),但在实际驾驶条件下准确估算可吸入颗粒物的排放量仍然具有挑战性。我们的目的是通过在韩国首尔进行路面测量,评估车辆产生的有机气溶胶(OA)和等效黑碳(eBC)的排放因子,以了解真实世界的可吸入颗粒物排放情况。我们使用一个配备了气溶胶质谱仪和乙氧基卤化仪的移动实验室来测量可吸入颗粒物的成分。在车辆隧道、城市道路和居民区进行了路面测量,并对测量点的特征进行了比较和分析。结果表明,随着汽车尾气的影响,OA 的浓度成比例增加,而 OA 的氧化态则降低。移动测量揭示了气溶胶的空间异质性,突出显示了车辆道路上新鲜 OA 的独特特征和居民区氧化态值的升高。车辆附近活跃的硝酸盐形成导致道路上的 NO3 浓度高于居民区。我们的研究表明,移动 PM 测量(包括 OA 和 eBC)对于直接评估排放清单很有价值。然而,由于车辆组成和交通状况的不同,计算出的环境系数可能不适用于其他城市,因此未来有必要制定针对具体城市的环境系数。此外,建议将此方法与传统排放清单相结合,以确定特定车辆类型的排放量。
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引用次数: 0
Satellite measurement data-based assessment of spatiotemporal characteristics of ultraviolet index (UVI) over the state of Johor, Malaysia 基于卫星测量数据评估马来西亚柔佛州上空紫外线指数(UVI)的时空特征
IF 1.1 Q4 METEOROLOGY & ATMOSPHERIC SCIENCES Pub Date : 2024-10-09 DOI: 10.1007/s44273-024-00041-0
Ninu Krishnan Modon Valappil, Fatimah Shafinaz Ahmad, Vijith Hamza

The study examines the spatiotemporal and statistical characteristics of the daily ultraviolet index (UVI) over the Johor state of Malaysia. The datasets utilized in this study are the Ozone Monitoring Instrument (OMI)/Aura satellite’s daily UVI observations between October 2004 and March 2023. The innovative trend analysis (ITA) method is employed to identify the statistical trend of daily UVI. Basic statistics of daily, monthly, and seasonal UVI are also carried out to better characterize UVI in the study area. The daily UVI data collected for the analysis exhibit wide variability, with more than 80% of the daily UVI data falling above UVI 8, indicating the severity of UV radiation (UVR) reaching the study area. The monthly and seasonal UVI also display highly varying characteristics, as observed in the daily data. The pixel-based analysis of ITA results indicates a significant increasing and decreasing trend of daily UVI in the region, with values varying between − 9.42 × 10−6 and 3.79 × 10−5. However, for the study area as a whole, UVI shows a significant increasing trend of 4.50 × 10−5. The influence of parameters such as cloud optical thickness (COT), solar zenith angle (SZA), and O3 column on the strength of UVR reaching the study area is also investigated. Based on the results, the study area is characterized by low thickness, broken clouds, and sometimes cloudless conditions. Overall, the results show that UVI in the study area is increasing, and therefore, proper health guidelines and direct UVR exposure regulations need to be implemented to reduce serious health risks associated with UVR exposure.

Graphical Abstract

本研究探讨了马来西亚柔佛州上空每日紫外线指数(UVI)的时空和统计特征。本研究使用的数据集是臭氧监测仪器(OMI)/Aura 卫星在 2004 年 10 月至 2023 年 3 月期间观测到的每日紫外线指数。采用创新趋势分析(ITA)方法来确定每日紫外线吸收剂量的统计趋势。此外,还对每日、每月和季节性 UVI 进行了基本统计,以更好地描述研究区域的 UVI 特征。分析所收集的每日紫外辐照度数据变化很大,超过 80% 的每日紫外辐照度数据都在紫外辐照度 8 以上,表明研究区域紫外辐照(UVR)的严重程度。月度和季节性紫外辐射指数也显示出与日数据相同的高度变化特征。基于像素的 ITA 分析结果表明,该地区的日紫外辐射指数呈明显的上升和下降趋势,数值在 - 9.42 × 10-6 和 3.79 × 10-5 之间变化。不过,就整个研究区域而言,UVI 呈显著上升趋势,为 4.50 × 10-5。此外,还研究了云光学厚度(COT)、太阳天顶角(SZA)和 O3 柱等参数对到达研究区域的紫外线辐射强度的影响。根据研究结果,研究区域的特点是云层厚度低、云层破碎,有时甚至是万里无云。总体而言,研究结果表明,研究区域的紫外线辐射量正在增加,因此需要实施适当的健康指南和紫外线直接照射法规,以减少紫外线照射对健康造成的严重危害。
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引用次数: 0
Variations of dissolved trace elements in precipitation and stream water in Japanese forest area: additional evidence of changing air pollution in the region 日本林区降水和溪水中溶解微量元素的变化:该地区空气污染变化的补充证据
IF 1.1 Q4 METEOROLOGY & ATMOSPHERIC SCIENCES Pub Date : 2024-09-02 DOI: 10.1007/s44273-024-00040-1
Masayuki Morohashi, Tatsuyoshi Saito, Masaaki Takahashi, Yayoi Inomata, Makoto Nakata, Masaki Ohno, Tomohiro Kose, Tsuyoshi Ohizumi, Ki-Cheol Shin, Ichiro Tayasu, Hiroyuki Sase

Trace elements released into the atmosphere by human activities, such as fossil fuel combustion, flow into forest ecosystems via wet and dry deposition and can flow out via mountainous stream water. The Kajikawa catchment site in Niigata Prefecture, located on the Sea of Japan side in central Japan, suffers from large amounts of acidic substance deposition due to its geographical conditions and meteorological seasonality and is affected by transboundary air pollution originating from the Asian continent due to northwesterly seasonal winds in winter. This study determined the concentrations of trace elements dissolved in precipitation and stream water to comprehensively evaluate the effects of transboundary air pollution on forest ecosystems. The results showed that the concentrations of trace elements and major inorganic ions in precipitation tended to be high in winter and low in summer. The fluxes of many trace elements also increased in winter, reflecting high precipitation amount. Except for Sr, the enrichment factors of the highly enriched trace elements did not show clear seasonality. Therefore, they were continuously influenced by anthropogenic activities. Furthermore, the stable Pb isotope ratio changed significantly during the observation period; however, this was not explained by seasonal changes. This study revealed that trace elements are transported to the Sea of Japan side in central Japan, especially in winter; however, their quantity and content change in response to changes in local and transboundary air pollution.

Graphical Abstract

人类活动(如化石燃料燃烧)释放到大气中的微量元素通过干湿沉积物进入森林生态系统,并通过山区溪水流出。新泻县的梶川集水区位于日本中部日本海一侧,由于其地理条件和气象季节性,该集水区受到大量酸性物质沉积的影响,而且由于冬季季节性西北风的影响,该集水区还受到来自亚洲大陆的跨境空气污染的影响。本研究测定了降水和溪水中溶解的微量元素浓度,以全面评估跨境空气污染对森林生态系统的影响。结果表明,降水中微量元素和主要无机离子的浓度呈冬季高、夏季低的趋势。许多微量元素的通量在冬季也有所增加,反映出降水量较高。除锶外,高富集微量元素的富集因子没有明显的季节性。因此,它们持续受到人为活动的影响。此外,在观测期间,稳定铅同位素比值发生了显著变化,但这并不能用季节变化来解释。这项研究表明,微量元素被输送到日本中部的日本海一侧,尤其是在冬季;但是,它们的数量和含量会随着当地和跨境空气污染的变化而变化。 图文摘要
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引用次数: 0
Aggregate risk assessment for multi-route exposure to hazardous chemicals caused by chemical accidents, with a focus on toluene 化学品事故导致的多路径接触危险化学品的总体风险评估,重点是甲苯
IF 1.1 Q4 METEOROLOGY & ATMOSPHERIC SCIENCES Pub Date : 2024-08-20 DOI: 10.1007/s44273-024-00039-8
Ji-Yun Jung, Si-Hyun Park, Ji-Eun Moon, Jun-Heon Yoon, Sung-Won Yoon, Cheol-Min Lee

Chemical accidents significantly impact environmental and human health. However, studies investigating the impacts of such accidents have primarily focused on single-route exposures, potentially underestimating the extent of damage. This study aimed to conduct an aggregate risk assessment for multi-route exposure to hazardous chemicals to ensure systematic and rational management of the health impacts on residents exposed to chemical accidents, considering the behavior of a hazardous chemical from a chemical accident within environmental media. Drawing upon a real chemical accident that occurred in Siheung, Gyeonggi-do, in 2019, leakage of 500 L of toluene over an hour was assumed. Employing a multimedia environmental dynamics model, the time-dependent concentrations across various environmental media were calculated, and the average daily dose (ADD), hazard quotient (HQ), and hazard index (HI) for each exposure route included in the multi-route exposure assessment were derived. Health risks were deemed present if the calculated HQ and HI values exceeded the threshold of 1. The results indicated the highest ADD values among the 0–9 age group, with inhalation exposure registering the highest ADD across all exposure routes. However, no significant health risks were observed, with both HQ and HI values not exceeding 1. This aggregate risk assessment approach is proposed as an effective preliminary evaluation method for health impact assessments in areas affected by chemical accidents.

Graphical Abstract

化学事故严重影响环境和人类健康。然而,调查此类事故影响的研究主要集中在单程暴露上,可能低估了损害程度。本研究旨在考虑化学事故中的危险化学品在环境介质中的行为,对危险化学品的多路径暴露进行综合风险评估,以确保系统、合理地管理化学事故对居民健康的影响。根据 2019 年发生在京畿道始兴市的真实化学事故,假设一小时内有 500 升甲苯泄漏。利用多媒体环境动力学模型,计算了各种环境介质中随时间变化的浓度,并得出了多途径接触评估中每种接触途径的日平均剂量(ADD)、危害商数(HQ)和危害指数(HI)。结果表明,0-9 岁年龄组的 ADD 值最高,在所有暴露途径中,吸入暴露的 ADD 值最高。不过,由于 HQ 值和 HI 值均未超过 1,因此未观察到明显的健康风险。建议将这种总体风险评估方法作为受化学品事故影响地区健康影响评估的一种有效的初步评估方法。
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引用次数: 0
PM2.5 and heavy metals in urban and agro-industrial areas: health risk assessment considerations 城市和农业工业区的 PM2.5 和重金属:健康风险评估考虑因素
IF 1.1 Q4 METEOROLOGY & ATMOSPHERIC SCIENCES Pub Date : 2024-07-26 DOI: 10.1007/s44273-024-00037-w
Shin-young Park, Jeong-In Jeon, Ji-Yun Jung, Sung-Won Yoon, Jaymin Kwon, Cheol-Min Lee

The study investigated PM2.5 and heavy metal pollutant concentrations in Seoul and Wonju, South Korea, emphasizing the importance of considering PM2.5 chemical constituents for health impact assessments. While PM2.5 concentrations were similar between the two cities with slight variations, heavy metal concentrations differed significantly. Regional sources, PM2.5 composition, and meteorological conditions influenced these variations. Exposure to Fe was highest in all areas, with some heavy metals exceeding permissible levels, stressing the need to consider regional characteristics in assessments. Different heavy metals influence health risks differently in each city. When examining the HI (the summation of the hazard quotient for heavy metals), Seoul remained below an HI value of 1, while Wonju exceeded this threshold when exposed to CTE concentrations. In Seoul, As had a significant health impact of PM2.5, while in Wonju, Mn was more influential. Source apportionment confirmed different pollution sources in Seoul and Wonju, affecting the distribution of PM2.5 constituents in the atmosphere. Effective PM2.5 management requires a comprehensive approach considering chemical constituents and health impacts not just mass-based PM2.5 management, emphasizing regional-specific assessments and policy considerations to mitigate health risks. Therefore, tailored management strategies based on regional characteristics are necessary.

Graphical Abstract

该研究调查了韩国首尔和原州的 PM2.5 和重金属污染物浓度,强调了在健康影响评估中考虑 PM2.5 化学成分的重要性。两个城市的 PM2.5 浓度相似,但略有不同,而重金属浓度则差异显著。地区来源、PM2.5 成分和气象条件影响了这些差异。铁的暴露量在所有地区都是最高的,一些重金属超过了允许水平,这强调了在评估中考虑地区特征的必要性。不同的重金属对每个城市的健康风险影响不同。在研究 HI 值(重金属危害商数的总和)时,首尔的 HI 值一直低于 1,而元州在暴露于 CTE 浓度时则超过了这一临界值。在首尔,砷对 PM2.5 的健康影响很大,而在原州,锰的影响更大。污染源分配证实,首尔和原州的污染源不同,影响了大气中 PM2.5 成分的分布。有效的 PM2.5 管理需要考虑化学成分和健康影响的综合方法,而不仅仅是基于质量的 PM2.5 管理,强调特定区域的评估和政策考虑,以减轻健康风险。因此,有必要根据地区特点制定有针对性的管理策略。
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引用次数: 0
Spatio-temporal variation of aerosol optical depth and black carbon mass concentration over five airports across Bangladesh: emphasis on effect of COVID-19 lockdown 孟加拉国五个机场上空气溶胶光学深度和黑碳质量浓度的时空变化:COVID-19 封锁的影响
IF 1.1 Q4 METEOROLOGY & ATMOSPHERIC SCIENCES Pub Date : 2024-07-25 DOI: 10.1007/s44273-024-00038-9
Khaled Shaifullah Joy, Shahid Uz Zaman, Md. Riad Sarkar Pavel, Md. Safiqul Islam, Abdus Salam

Globally, the COVID-19 outbreak has had a devastating impact on both health and economy. In contrast, the reduction in anthropogenic emissions has resulted in a major improvement in air quality. In this study, US National Aeronautics and Space Administration (NASA) satellite datasets and related reanalysis model data were used with validation using ground-based data to evaluate the effects of aviation-based emissions on aerosol optical depth (AOD) and black carbon (BC). The contributions from five airports in Bangladesh were assessed during the pre-lockdown (01 Jan to 22 March), lockdown (23 March to 30 May), and post-lockdown (31 May to 30 Aug) periods in 2019 and 2020. The study’s findings show that during the 2020 lockdown, AOD and BC concentrations significantly decreased at all five airports. The overall decline of AOD was ~ 18.5% (13.1% to 22.8%) and BC was ~ 18.1% (16.6% to 22.2%) in 2020 compared to 2019. The three international airports that were examined—Dhaka, Chattagram, and Sylhet—showed an average reduction of about ~ 9.7%, while Jashore and Barisal—two domestic airports—saw a minor increase in AOD of ~ 0.8% over the same period. However, the average BC concentration at both international and domestic airports dropped by ~ 9.8% and ~ 10.2%, respectively. This is the first study to use reanalysis datasets in Bangladesh to evaluate air pollution levels and aviation-based emissions. The results highlight the significant impact of reduced aviation activity on air quality and provide valuable insights for future air pollution management strategies.

Graphical Abstract

在全球范围内,COVID-19 的爆发对健康和经济都造成了破坏性影响。与此相反,人为排放的减少却大大改善了空气质量。本研究使用美国国家航空航天局(NASA)的卫星数据集和相关的再分析模型数据,并利用地面数据进行验证,以评估航空排放对气溶胶光学深度(AOD)和黑碳(BC)的影响。对孟加拉国五个机场在 2019 年和 2020 年禁飞前(1 月 1 日至 3 月 22 日)、禁飞中(3 月 23 日至 5 月 30 日)和禁飞后(5 月 31 日至 8 月 30 日)期间的贡献进行了评估。研究结果表明,在 2020 年关闭期间,所有五个机场的 AOD 和 BC 浓度均显著下降。与 2019 年相比,2020 年 AOD 的总体降幅约为 18.5%(13.1% 至 22.8%),BC 的总体降幅约为 18.1%(16.6% 至 22.2%)。接受调查的三个国际机场--达卡、恰塔格拉姆和西尔赫特--的平均降幅约为 9.7%,而两个国内机场--贾肖尔和巴里萨尔--的 AOD 同期略有增加,增幅约为 0.8%。不过,国际机场和国内机场的 BC 浓度平均值分别下降了约 9.8% 和约 10.2%。这是首次使用再分析数据集对孟加拉国的空气污染水平和航空排放进行评估的研究。研究结果凸显了航空活动减少对空气质量的重大影响,并为未来的空气污染管理策略提供了宝贵的见解。
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引用次数: 0
Large-eddy simulation of the effects of a tower structure on wind velocity and drag coefficient 塔架结构对风速和阻力系数影响的大涡流模拟
IF 1.1 Q4 METEOROLOGY & ATMOSPHERIC SCIENCES Pub Date : 2024-07-12 DOI: 10.1007/s44273-024-00036-x
Takenobu Michioka

A large-eddy simulation was implemented for the flow around a cylindrical observation tower to investigate the effects of the tower structure on wind speed and drag coefficient. The mean wind velocity accelerates above the tower because flow separation occurs at the leading edge of the top of the tower. The drag coefficient is strongly linked to the Reynolds shear stress. Above the tower, the Reynolds shear stresses change from negative to positive within the recirculation zone and return to a negative value in the latter half of the tower because of the steep velocity gradients near the top of the tower. The change in the Reynolds shear stress results in an inaccurate drag coefficient. When one anemometer is used, a location at over 10 m above the top of the tower is suitable for measuring the drag coefficient accurately. When two anemometers are used, the Reynolds shear stress can be measured more accurately. Although the effects of the tower on the drag coefficient are not entirely removed, the use of two anemometers is a promising approach to estimate the drag coefficient in a tower.

Graphical Abstract

对圆柱形观测塔周围的流动进行了大涡流模拟,以研究塔结构对风速和阻力系数的影响。由于塔顶前缘发生了流体分离,因此塔上方的平均风速加快。阻力系数与雷诺切应力密切相关。在塔架上方,由于塔顶附近的速度梯度较陡,雷诺切应力在再循环区内由负值变为正值,并在塔架后半部分恢复为负值。雷诺切应力的变化导致阻力系数不准确。使用一个风速计时,塔顶上方 10 米以上的位置适合精确测量阻力系数。使用两个风速计时,可以更精确地测量雷诺剪应力。虽然不能完全消除塔架对阻力系数的影响,但使用两个风速计估算塔架的阻力系数是一种很有前途的方法。
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引用次数: 0
期刊
Asian Journal of Atmospheric Environment
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