AOD

AOD
  • 文章类型: Journal Article
    人类产生的气溶胶污染逐渐改变了大气的化学和物理属性,导致天气模式发生重大变化,并对农业产量产生不利影响。本研究通过分析1998年至2019年印度的时间序列数据,评估了水稻和玉米作物的天气和人为气溶胶变化导致的农业生产力损失。气象变量的平均值,如最高温度(TMAX),最低温度(TMIN),降雨,和相对湿度,以及气溶胶光学深度(AOD),也显示出越来越大的趋势,在此期间,土壤水分的平均值和吸收的光合有效辐射(FAPAR)的比例呈下降趋势。这项研究的主要发现是,天气变量的异常变化,如最高和最低温度,降雨,相对湿度,土壤湿度,和FAPAR导致水稻和玉米产量减少约(2.55%,2.92%,2.778%,4.84%,2.90%,和2.82%)和(5.12%,6.57%,6.93%,6.54%,4.97%,和5.84%),分别。然而,气溶胶污染的增加也导致水稻和玉米减产7.9%和8.8%,分别。总之,这项研究提供了天气有害影响的明确证据,FAPAR,和AOD变异性对研究期间印度水稻和玉米产量的影响。同时,对水稻和玉米产量的时间序列分析显示出增长趋势,分别为808.8万吨/年和56.1万吨/年,分别,由于采用了越来越先进的农业技术,最好的肥料和灌溉,气候适应型品种,和其他因素。展望未来,目前的挑战是制定有效的长期战略,以应对气溶胶造成的空气污染,并解决其对农业生产和粮食安全的不利影响。
    Human-generated aerosol pollution gradually modifies the atmospheric chemical and physical attributes, resulting in significant changes in weather patterns and detrimental effects on agricultural yields. The current study assesses the loss in agricultural productivity due to weather and anthropogenic aerosol variations for rice and maize crops through the analysis of time series data of India spanning from 1998 to 2019. The average values of meteorological variables like maximum temperature (TMAX), minimum temperature (TMIN), rainfall, and relative humidity, as well as aerosol optical depth (AOD), have also shown an increasing tendency, while the average values of soil moisture and fraction of absorbed photosynthetically active radiation (FAPAR) have followed a decreasing trend over that period. This study\'s primary finding is that unusual variations in weather variables like maximum and minimum temperature, rainfall, relative humidity, soil moisture, and FAPAR resulted in a reduction in rice and maize yield of approximately (2.55%, 2.92%, 2.778%, 4.84%, 2.90%, and 2.82%) and (5.12%, 6.57%, 6.93%, 6.54%, 4.97%, and 5.84%), respectively. However, the increase in aerosol pollution is also responsible for the reduction of rice and maize yield by 7.9% and 8.8%, respectively. In summary, the study presents definitive proof of the detrimental effect of weather, FAPAR, and AOD variability on the yield of rice and maize in India during the study period. Meanwhile, a time series analysis of rice and maize yields revealed an increasing trend, with rates of 0.888 million tons/year and 0.561 million tons/year, respectively, due to the adoption of increasingly advanced agricultural techniques, the best fertilizer and irrigation, climate-resilient varieties, and other factors. Looking ahead, the ongoing challenge is to devise effective long-term strategies to combat air pollution caused by aerosols and to address its adverse effects on agricultural production and food security.
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  • 文章类型: Journal Article
    背景:与普通人群相比,寻求酒精和其他药物(AOD)治疗的个体始终经历更高的自杀行为和自杀死亡率。通过将住宅AOD治疗数据与行政医疗保健和死亡数据集联系起来,我们的目的是检查与自杀相关的行为,并确定这些事件在出院后的风险和保护因素。
    方法:参与者包括1056名年龄在18-69岁之间的人(M=32.06,SD=9.55,男性=696,65.9%),他们在昆士兰州的三个住宅治疗设施中入院。澳大利亚从2014年1月1日至2016年12月31日。治疗数据与行政医院有关,急诊科(ED),心理健康服务,和出院后2年的死亡登记数据。ICD-10代码用于识别和分析与自杀相关的事件。
    结果:出院后2年内,175人(16.6%)有自杀相关事件(n=298次)。发作比例最高(11.1%)发生在出院后1个月内。复发性自杀相关事件的风险较高与接受残疾支持养老金相关(aHR=1.69(95CI:1.10,2.59),先前两次或更多次住院治疗AOD(aHR=1.49(95CI:1.30,2.15)。完成住院治疗与自杀相关事件的风险较低相关(aHR=0.54(95CI:0.35,0.83)。
    结论:自杀意念的合并,尝试,死亡变成单一的结果过度简化了它们复杂的性质和相互作用。对一个服务提供商的独家关注限制了普遍性,数据限制和错误排除了许多分析。
    结论:了解住院治疗出院后的自杀行为和关键危险时期对于改善持续护理至关重要,制定有效的自杀预防,并在这一高危人群中实施有针对性的干预措施。
    BACKGROUND: Individuals seeking alcohol and other drug (AOD) treatment consistently experience higher rates of suicidal behaviours and death by suicide when compared to the general population. By linking residential AOD treatment data to administrative healthcare and death datasets, we aimed to examine suicide-related behaviours and identify risk and protective factors for these events following discharge from residential treatment.
    METHODS: Participants included 1056 individuals aged 18-69 (M = 32.06, SD = 9.55, male = 696,65.9 %) admitted to three residential treatment facilities in Queensland, Australia from January 1, 2014 to December 31, 2016. Treatment data was linked to administrative hospital, emergency department (ED), mental health service, and Registry of Deaths data 2-years post-discharge. ICD-10 codes were used to identify and analyse suicide-related events.
    RESULTS: Within 2-years post-discharge, 175 (16.6 %) individuals had a suicide-related event (n = 298 episodes). The highest proportion of episodes (11.1 %) occurred within 1-month of discharge. Higher risk of a recurrent suicide-related event was associated with receiving a Disability Support Pension (aHR = 1.69 (95%CI:1.10,2.59), two or more previous episodes of residential AOD treatment (aHR = 1.49 (95%CI:1.30,2.15). Completing residential treatment was associated with a lower risk of suicide-related events (aHR = 0.54 (95%CI:0.35,0.83).
    CONCLUSIONS: The amalgamation of suicidal ideation, attempts, and death into a single outcome oversimplifies their complex nature and interplay. The exclusive focus on one service provider limits generalisability, and data constraints and missingness preclude many analyses.
    CONCLUSIONS: Understanding suicidal behaviours and critical risk periods following discharge from residential treatment is crucial for improving continuing care, developing effective suicide prevention, and implementing targeted interventions among this high-risk population.
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  • 文章类型: Journal Article
    气溶胶光学深度(AOD)是评估区域空气质量的重要指标。解决区域和城市污染问题,对高分辨率AOD产品有要求,因为现有数据的分辨率非常粗略。为了解决这个问题,我们在坎普尔(26.4499°N,80.3319°E),使用Landsat8图像位于印度恒河平原(IGP)区域,并实现了算法SEMARA,它结合了SARA(简化的气溶胶检索算法)和SREM(简化和鲁棒的表面反射率估计)。我们的方法利用了Landsat8的绿色带,产生了令人印象深刻的30mAOD空间分辨率,并通过可用的AERONET观测进行了严格验证。检索到的AOD与0.997的高相关系数(r),0.035的低均方根误差和-4.91%的均方根偏差非常吻合。我们在研究区域的农业周期的作物和收割期,评估了在不同土地类别中使用缩减规模的MODIS(MCD19A2)AOD产品检索到的AOD。值得注意的是,在坎普尔的建筑区域,与植被相比,SEMRA算法与MODISAOD产品具有更强的相关性,贫瘠的地区和水体。与耕种期相比,SEMARA方法被证明在收割期的贫瘠和建成区土地类别上的AOD检索更有效。这项研究在IGP站上首次对SEMRA检索的高分辨率AOD和MODISAOD产品进行了比较检查。
    Aerosol optical depth (AOD) serves as a crucial indicator for assessing regional air quality. To address regional and urban pollution issues, there is a requirement for high-resolution AOD products, as the existing data is of very coarse resolution. To address this issue, we retrieved high-resolution AOD over Kanpur (26.4499°N, 80.3319°E), located in the Indo-Gangetic Plain (IGP) region using Landsat 8 imageries and implemented the algorithm SEMARA, which combines SARA (Simplified Aerosol Retrieval Algorithm) and SREM (Simplified and Robust Surface Reflectance Estimation). Our approach leveraged the green band of the Landsat 8, resulting in an impressive spatial resolution of 30 m of AOD and rigorously validated with available AERONET observations. The retrieved AOD is in good agreement with high correlation coefficients (r) of 0.997, a low root mean squared error of 0.035, and root mean bias of - 4.91%. We evaluated the retrieved AOD with downscaled MODIS (MCD19A2) AOD products across various land classes for cropped and harvested period of agriculture cycle over the study region. It is noticed that over the built-up region of Kanpur, the SEMARA algorithm exhibits a stronger correlation with the MODIS AOD product compared to vegetation, barren areas and water bodies. The SEMARA approach proved to be more effective for AOD retrieval over the barren and built-up land categories for harvested period compared with the cropping period. This study offers a first comparative examination of SEMARA-retrieved high-resolution AOD and MODIS AOD product over a station of IGP.
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  • 文章类型: Journal Article
    这项研究调查了COVID-19封锁对颗粒物浓度的影响,特别是科威特的PM2.5和PM10。我们研究了2020年封锁与2017-2019年相应时期之间PM2.5和PM10的变化,还调查了“宵禁”和“非宵禁”时间之间PM变化的差异。我们应用混合效应回归来研究决定PM变异性的因素(即,灰尘和气象协变量),并处理了基于卫星的气溶胶光学深度(AOD),以确定气溶胶负荷的空间变异性。结果显示,与前三年(2017-2019年)相比,封锁期间的PM2.5浓度较低(33μg/m3);然而,PM10浓度(122.5μg/m3)相对于2017年(116.6μg/m3)增加,和2019年(92.8μg/m3)。消除“灰尘影响”后,PM2.5和PM10水平下降了18%和31%,分别。混合效应回归模型表明,高温和高风速分别是高PM2.5和PM10的主要贡献者,除了雾霾和吹起的灰尘。这项研究强调,人为源排放的减少被干旱地区的粉尘事件和不利的气象所淹没,封锁并没有降低科威特的高浓度PM。
    This study investigated the impact of COVID-19 lockdown on particulate matter concentrations, specifically PM2.5 and PM10, in Kuwait. We studied the variations in PM2.5 and PM10 between the lockdown in 2020 with the corresponding periods of the years 2017-2019, and also investigated the differences in PM variations between the \'curfew\' and \'non curfew\' hours. We applied mixed-effect regression to investigate the factors that dictate PM variability (i.e., dust and meteorological covariates), and also processed satellite-based aerosol optical depths (AOD) to determine the spatial variability in aerosol loads. The results showed low PM2.5 concentration during the lockdown (33 μg/m3) compared to the corresponding previous three years (2017-2019); however, the PM10 concentration (122.5 μg/m3) increased relative to 2017 (116.6 μg/m3), and 2019 (92.8 μg/m3). After removing the \'dust effects\', both PM2.5 and PM10 levels dropped by 18% and 31%, respectively. The mixed-effect regression model showed that high temperature and high wind speed were the main contributors to high PM2.5 and PM10, respectively, in addition to the dust haze and blowing dust. This study highlights that the reductions of anthropogenic source emissions are overwhelmed by dust events and adverse meteorology in arid regions, and that the lockdown did not reduce the high concentrations of PM in Kuwait.
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  • 文章类型: Journal Article
    背景:尽管PM2.5(空气动力学直径小于2.5µm的细颗粒物)是德克萨斯州非常关注的空气污染物,有限的监管监督员对决策和环境研究构成了重大挑战。
    目的:这项研究旨在通过使用新颖的机器学习方法并结合卫星衍生的气溶胶光学深度(AOD)和各种天气和土地利用变量,在每日的精细空间尺度上预测PM2.5浓度。
    方法:我们从2013年到2017年在德克萨斯州编制了一个综合数据集,包括来自监管监测器的地面PM2.5浓度;基于从MODIS卫星检索到的图像的1公里分辨率的AOD值;和天气,土地利用,人口密度,在其他人中。我们分别建立了每年的预测模型,使用两种称为梯度提升树和随机森林的机器学习方法来估计PM2.5浓度。我们使用样本内和样本外验证评估了模型预测性能。
    结果:我们的预测模型展示了出色的样本模型性能,如从梯度增强模型(0.94-0.97)和随机森林模型(0.81-0.90)生成的高R2值所示。然而,对于梯度增强模型,样本外R2值在0.52-0.75的范围内,对于随机森林模型,样本外R2值在0.44-0.69的范围内。模型性能在不同年份略有不同。在德克萨斯州东部观察到预测的PM2.5浓度随时间的总体下降趋势。
    我们利用机器学习方法来预测德克萨斯州的PM2.5水平。梯度提升和随机森林模型都表现良好。梯度提升模型的性能略优于随机森林模型。我们的模型显示出优异的样本内预测性能(R2>0.9)。
    BACKGROUND: Although PM2.5 (fine particulate matter with an aerodynamic diameter less than 2.5 µm) is an air pollutant of great concern in Texas, limited regulatory monitors pose a significant challenge for decision-making and environmental studies.
    OBJECTIVE: This study aimed to predict PM2.5 concentrations at a fine spatial scale on a daily basis by using novel machine learning approaches and incorporating satellite-derived Aerosol Optical Depth (AOD) and a variety of weather and land use variables.
    METHODS: We compiled a comprehensive dataset in Texas from 2013 to 2017, including ground-level PM2.5 concentrations from regulatory monitors; AOD values at 1-km resolution based on images retrieved from the MODIS satellite; and weather, land-use, population density, among others. We built predictive models for each year separately to estimate PM2.5 concentrations using two machine learning approaches called gradient boosted trees and random forest. We evaluated the model prediction performance using in-sample and out-of-sample validations.
    RESULTS: Our predictive models demonstrate excellent in-sample model performance, as indicated by high R2 values generated from the gradient boosting models (0.94-0.97) and random forest models (0.81-0.90). However, the out-of-sample R2 values fall within a range of 0.52-0.75 for gradient boosting models and 0.44-0.69 for random forest models. Model performance varies slightly across years. A generally decreasing trend in predicted PM2.5 concentrations over time is observed in Eastern Texas.
    UNASSIGNED: We utilized machine learning approaches to predict PM2.5 levels in Texas. Both gradient boosting and random forest models perform well. Gradient boosting models perform slightly better than random forest models. Our models showed excellent in-sample prediction performance (R2 > 0.9).
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  • 文章类型: Journal Article
    大气气溶胶通过影响辐射影响地表臭氧浓度,但机制和主导因素尚不清楚。因此,本文借助大气辐射传输(SBDART)模型,分析了中国干旱和半干旱地区气溶胶辐射地表臭氧的变化。结果表明,气溶胶光学厚度(AOD)和粗颗粒物(PM10)具有相同的趋势,春季和冬季高值,夏季和秋季低值。地表臭氧在春季和夏季高,在秋季和冬季低。地表臭氧在春季和夏季较高,在秋季和冬季较低。在冬天,主要是二次污染物以高污染水平为主。在剩下的季节里,灰尘的混合物,机动车尾气,烟尘以低污染水平为主。地表臭氧与细颗粒呈正相关,与粗颗粒呈负相关。各季节温度与地表臭氧呈正相关,夏季与PM10呈负相关,秋天,和冬天。降水与每个季节的PM10和冬季和春季的地表臭氧呈负相关。基于后线轨迹模型对污染严重城市呼和浩特市地表臭氧和PM10来源的分析表明,气流轨迹主要输送来自内蒙古西北部和蒙古西部的地表臭氧和PM10污染。在尘土飞扬的天气里,到达地球表面的辐射减少和气溶胶的冷却作用导致温度降低,减缓了表面臭氧前体的化学反应速度,导致地表臭氧浓度降低。该研究可为我国干旱半干旱地区气溶胶和地面臭氧控制提供理论参考。
    Atmospheric aerosols affect surface ozone concentrations by influencing radiation, but the mechanism and dominant factors are unclear. Therefore, this paper analyses the changes in aerosol-radiative-surface ozone in China\'s arid and semi-arid regions with the help of the Atmospheric Radiative Transfer (SBDART) model. The results suggest that Aerosol Optical Depth (AOD) and coarse Particulate Matter (PM10) have the same trend, with high values in spring and winter and low values in summer and autumn. Surface ozone is high in spring and summer and low in autumn and winter. Surface ozone is higher in spring and summer and lower in autumn and winter. In winter, mainly secondary pollutants are dominated by high pollution levels. In the rest of the seasons, a mixture of dust, motor vehicle exhaust, and soot is dominated by low pollution levels. Surface ozone is positively correlated with fine particles and negatively correlated with coarse particles. Temperature is positively correlated with surface ozone in all seasons and negatively correlated with PM10 in summer, autumn, and winter. Precipitation negatively correlates with PM10 each season and surface ozone in winter and spring. Analysis of surface ozone and PM10 sources in the more polluted city of Hohhot based on the back-line trajectory model showed that airflow trajectories mainly transported surface ozone and PM10 pollution from northwestern Inner Mongolia and western Mongolia. During dusty solid weather, the decrease in radiation reaching the Earth\'s surface and the cooling effect of aerosols lead to lower temperatures, which slows down the rate of chemical reactions of precursors of surface ozone, resulting in lower ozone concentrations at the surface. This study can provide a theoretical reference for aerosol and surface ozone control in arid and semi-arid areas of China.
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  • 文章类型: Journal Article
    Terra和Aqua卫星上的中分辨率成像光谱仪(MODIS)仪器可提供多种大气参数的测量。本文重点研究了表示混浊像素数除以像素数的云分数数据,并可通过1°x1°网格空间分辨率与每日或每月的时间分辨率。这项研究的目的是提出一种称为时空实现算法(STIA)的新颖方法,用于分析卫星每日1°x1°网格云分数的平均值•比较MODIS在Aqua和Terra卫星上检索到的两个数据集,以获得有关下午和早晨的云形成的信息,分别,从而提高了时间分辨率。•将实际参数与由具有更好分辨率的不同卫星上的仪器检索的其他参数进行比较。作为STIA应用的一个例子,本研究使用Aura卫星上的臭氧监测仪器(OMI)收集的气溶胶光学深度(AOD)与MODIS仪器进行比较,以实现和增强网格单元的空间分辨率。
    The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard Terra and Aqua satellites provides measurements of several atmospheric parameters. This paper focuses on the cloud fraction data representing the number of cloudy pixels divided by the total number of pixels, and available through 1° x 1° grids spatial resolution with daily or monthly temporal resolution. The aim of the study is to propose a novel method called The Spatial-Temporal Implementation Algorithm (STIA) for analysing satellite daily 1° x 1°grid cloud fraction average values for•Comparing two datasets retrieved by MODIS aboard Aqua and Terra satellites to obtain information on the cloud formation in the afternoon and morning, respectively, thus enhancing the temporal resolution.•Comparing the actual parameter with others retrieved by instruments aboard of different satellites characterized by a better resolution. As an example of STIA application, this study uses the Aerosol Optical Depth (AOD) collected by the Ozone Monitoring Instrument (OMI) on board of Aura satellite for comparison with MODIS instrument to achieve and enhanced spatial resolution of the grid-cell.
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  • 文章类型: Journal Article
    急性橡树衰退是一种影响很大的疾病,会导致躯干坏死性病变,树冠变薄,橡树最终死亡。四种细菌与病变有关-BrenneriaGoodwinii,赤霉素,维氏拉恩氏菌和大英百科全书-尽管这些细菌也提出了表观/内生的生活方式。然而,对它们的环境水库或它们的内生定植途径知之甚少。这项工作旨在研究四种AOD相关细菌在根际土壤中长时间存活的能力,离体的叶子和橡子,并设计一种合适的方法来恢复它们。该方法在与健康和有症状的橡树相关的现场样品上进行了试验。体外研究表明,这些物种中的大多数可以在每种样品类型中存活至少六周。现场样本的结果表明,维科里亚和G.quercinecans在环境上似乎很普遍,表明多种内生菌定植途径可能是合理的。仅从健康和有症状的树木的橡子中鉴定出B.Goodwinii和L.Britannica,表明它们可能是内生种子微生物组的遗传成员,尽管它们有能力在宿主之外生存,它们的环境发生是有限的。未来的研究应集中在针对AOD非生物因素的预防措施上,内生细菌如何转变为致病周期,以及对AOD较不敏感的弹性种子储备的鉴定。
    Acute oak decline is a high-impact disease causing necrotic lesions on the trunk, crown thinning and the eventual death of oak. Four bacterial species are associated with the lesions-Brenneria goodwinii, Gibbsiella quercinecans, Rahnella victoriana and Lonsdalea Britannica-although an epi-/endophytic lifestyle has also been suggested for these bacteria. However, little is known about their environmental reservoirs or their pathway to endophytic colonisation. This work aimed to investigate the ability of the four AOD-associated bacterial species to survive for prolonged periods within rhizosphere soil, leaves and acorns in vitro, and to design an appropriate method for their recovery. This method was trialled on field samples related to healthy and symptomatic oaks. The in vitro study showed that the majority of these species could survive for at least six weeks within each sample type. Results from the field samples demonstrated that R. victoriana and G. quercinecans appear environmentally widespread, indicating multiple routes of endophytic colonisation might be plausible. B. goodwinii and L. britannica were only identified from acorns from healthy and symptomatic trees, indicating they may be inherited members of the endophytic seed microbiome and, despite their ability to survive outside of the host, their environmental occurrence is limited. Future research should focus on preventative measures targeting the abiotic factors of AOD, how endophytic bacteria shift to a pathogenic cycle and the identification of resilient seed stock that is less susceptible to AOD.
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  • 文章类型: Journal Article
    自2010年成功推出地球静止海洋彩色成像仪(GOCI)以来,GOCIYonsei气溶胶检索(YAER)算法一直在不断更新,以检索每小时的气溶胶光学特性。GOCI-II有4个通道,包括紫外线,更精细的空间分辨率(250米),与GOCI相比,该公司于2020年2月在GEO-KOMPSAT-2B(GK-2B)卫星上发射。在这项研究中,我们基于YAER算法在许多方面的改进性能将其扩展到GOCI-II数据,并介绍了从GOCI-II数据中检索到的气溶胶光学特性的第一个结果。利用地球静止轨道中GOCI-II和GOCI之间的重叠周期,我们介绍了东亚地区高气溶胶负荷病例的GOCI-II气溶胶检索结果,并表明它们与GOCI的空间分布一致。此外,GOCI-II以更高的空间分辨率提供AOD,揭示气溶胶浓度的细微变化。一年数据的验证结果表明,与气溶胶机器人网络(AERONET)数据相比,GOCI-IIAOD的相关系数为0.83,预期误差(EE)的比率为59.4%。我们比较了GOCI和GOCI-IIAOD的统计指标,以评估两个数据集之间的一致性。此外,通过比较网格GOCI和GOCI-IIAOD产品,发现两个数据集之间存在很强的相关性。预计GOCI-II的数据将继续高精度的长期气溶胶记录,可用于解决东亚的空气质量问题。
    Since the Geostationary Ocean Color Imager (GOCI) was successfully launched in 2010, the GOCI Yonsei aerosol retrieval (YAER) algorithm has been continuously updated to retrieve hourly aerosol optical properties. GOCI-II has 4 more channels including UV, finer spatial resolution (250 m), and daily full disk coverage as compared to GOCI, and was launched in February 2020, onboard the GEO-KOMPSAT-2B (GK-2B) satellite. In this study, we extended the YAER algorithm to GOCI-II data based on its improved performance in many aspects and present the first results of aerosol optical properties retrieved from GOCI-II data. Utilizing the overlapping period between the GOCI-II and GOCI in geostationary Earth orbit, we present GOCI-II aerosol retrievals for high aerosol-loading cases over East Asia and show that these have a consistent spatial distribution with those from GOCI. Furthermore, GOCI-II provides AOD at an even higher spatial resolution, revealing finer changes in aerosol concentrations. Validation results for one year data show that the GOCI-II AOD has a correlation coefficient of 0.83 and a ratio within the expected error (EE) of 59.4 % when compared with the aerosol robotic network (AERONET) data. We compared statistical metrics for the GOCI and GOCI-II AODs to assess the consistency between the two datasets. In addition, it was found that there is a strong correlation between the two datasets from the comparison of gridded GOCI and GOCI-II AOD products. It is expected that data from GOCI-II will continue long-term aerosol records with high accuracy that can be used to address air-quality issues over East Asia.
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  • 文章类型: Journal Article
    研究了2019年CorronaVirus病(COVID-19)限制性措施对西方气溶胶光学深度(AOD)和黑碳(BC)浓度的影响,中央,以及使用卫星观测的印度恒河平原东部(IGP)。由于COVID-19引起的封锁措施,与2020年封锁前和2015-2019年封锁同期相比,整个IGP的AOD和BC浓度显着下降。在完全封锁期间,在中央IGP中观察到AOD和BC的最大下降(26.5%和10.1%),其次是2015-2019年同期的西部IGP(24.9%和5.2%)和东部IGP(23.2%和4.9%)。在COVID-19封锁期间,我们已经消除了季节性对气溶胶特性的影响,以2015-2019年期间的平均季节性变化为参考,并预测正常情景下封锁期的假设AOD和BC。在封锁期间,假设的AOD和BC(在正常情况下)与检索到的AOD和BC之间的差异是仅由于封锁而导致的AOD和BC浓度的绝对百分比变化。这种消除季节性影响是一种新颖的方法。在封锁期间,中部IGP的AOD和BC绝对下降了38.5%和18.2%,其次是西部IGP(34.6%和7.7%)和东部IGP(25.9%和11.5%)。观察到的AOD绝对减少,26-39%,显著高于AOD的全球平均降低2-5%。西部主要地区的CALIPSO气溶胶亚型,中央,东部IGP表明封锁前后人为活动的普遍性。在封锁期间,IGP受到天然气溶胶的影响,西部和中部IGP的矿物粉尘和污染粉尘,和来自东部IGP海洋地区的气溶胶。与封锁后的总柱相比,边界层内气溶胶的补充要快得多。总的来说,这项研究揭示了在COVID-19引起的封锁期间人为排放的减少,导致IGP空气质量暂时改善。我们的研究全面分析了COVID-19封锁对IGP气溶胶特性的影响,并强调了AOD(约40%)和BC(约20%)的空前降低,由于实施封锁和随后停止气溶胶来源,消除季节性影响。
    Impact of COrona VIrus Diseases 2019 (COVID-19) restrictive measures on aerosol optical depth (AOD) and black carbon (BC) concentration is investigated for the western, central, and eastern Indo-Gangetic Plain (IGP) using satellite-based observations. Due to COVID-19-induced lockdown measures, a noticeable decline in AOD and BC concentrations was observed across the IGP when compared to pre-lockdown period of 2020 and the lockdown concurrent period of 2015-2019. During the total lockdown period, a maximum drop in AOD and BC was observed in the central IGP (26.5 % and 10.1 %), followed by western IGP (24.9% and 5.2%) and eastern IGP (23.2 % and 4.9 %) with respect to the same period of 2015-2019. We have removed seasonal influences on aerosol properties during the COVID-19 lockdown, by taking average seasonal variations during the period of 2015-2019 as reference and projecting the hypothetical AOD and BC for the lockdown period under normal scenario. The difference between the hypothetical AOD and BC (under normal scenario) and the retrieved AOD and BC for the lockdown period is the absolute percentage change in AOD and BC concentration due to the lockdown alone. This elimination of seasonal influence is a novel approach. Central IGP showed an absolute decrease in AOD and BC of 38.5% and 18.2% during the lockdown period followed by western IGP (34.6% and 7.7%) and eastern IGP (25.9% and 11.5%). The observed absolute reduction in AOD, 26-39 %, is significantly higher than the global average reduction in AOD of 2-5%. CALIPSO-derived aerosol sub-types over major location of the western, central, and eastern IGP suggests prevalence of anthropogenic activities during pre- and post-lockdown periods. During the lockdown, IGP was influenced by aerosols from natural sources, with mineral dust and polluted dust in the western and central IGP, and aerosols from marine regions in the eastern IGP. Replenishment of aerosols within the boundary layer were far quicker when compared to total column during post-lockdown. Overall, the study reveals a reduction in anthropogenic emissions during the COVID-19-induced lockdowns, leading to temporary improvements in air quality over the IGP. Our study presents a comprehensive analysis of COVID-19 lockdown impact on aerosols properties over the IGP and highlights unprecedented reductions in AOD (~ 40 %) and BC (~ 20 %), due to imposition of lockdown and subsequent cessation of aerosol sources, by removing seasonal influences.
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