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Land Cover Regulates the Spatial Variability of Temperature Response to the Direct Radiative Effect of aerosols

GEOPHYSICAL RESEARCH LETTERS 2019年第15期46卷 8995-9003页

作者： Chakraborty, T. Lee, X. Yale Univ Sch Forestry & Environm Studies New Haven CT 06511 USA

Aerosol impact on the surface temperature varies between the shortwave and the longwave components of radiation, depends on the time of the day, and is modulated by underlying biophysical processes. We disentangle these complexities by isolating the direct surface shortwave and longwave radiative effects from a global reanalysis data product and calculating their spatially explicit climate sensitivities. Higher sensitivity is found for the longwave component and is driven by a combination of spatial variability of aerosol species and biophysical control of the underlying surface. The opposing shortwave and longwave effects reduce the global mean diurnal temperature range by 0.47 K, with almost half the contribution coming from aerosols of anthropogenic origin. We also find evidence of an increasing trend in the local climate sensitivity in the equatorial zone, possibly caused by deforestation. These surface processes can partially explain why the climate forcing efficacy of aerosols exceeds unity. Plain Language summary The radiative effect of aerosols is disproportionately stronger at the Earth's surface compared to the top of the atmosphere and depends on the time of the day and aerosol properties. Moreover, the local surface temperature response to aerosols depends on both incoming energy and the surface energy dissipation via the properties of the underlying surface. To disentangle these complex interactions, we use a theoretical framework to separate surface temperature response to the aerosol shortwave and longwave radiative effects for the world's land surfaces using a reanalysis dataset. We find a stronger local climate sensitivity to the longwave radiative effect than to the shortwave. This is partly due to the incidental collocation of regions of high local climate sensitivity with regions containing coarse mineral dust aerosols. The opposite directions of the surface shortwave and longwave radiative effects reduce the diurnal temperature range, particular

关键词： aerosols Biophysical control Radiative forcing Climate sensitivity Surface temperature

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Classification of aerosols over Saudi Arabia from 2004-2016

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ATMOSPHERIC ENVIRONMENT 2020年 241卷 117785-117785页

作者： Ali, Arfan Nichol, Janet E. Bilal, Muhammad Qiu, Zhongfeng Mazhar, Usman Wahiduzzaman, Md Almazroui, Mansour Islam, M. Nazrul Nanjing Univ Informat Sci & Technol Sch Marine Sci Nanjing 210044 Peoples R China Univ Sussex Sch Global Studies Dept Geog Brighton E Sussex England Nanjing Univ Informat Sci & Technol Sch Remote Sensing & Geomat Engn Nanjing 210044 Peoples R China Nanjing Univ Informat Sci & Technol Joint Int Res Lab Climate & Environm Change ILCEC Collaborat Innovat Ctr Forecast & Evaluat Meteoro Key Lab Meteorol DisasterMinist Educ KLMEInst C Nanjing 210044 Peoples R China King Abdulaziz Univ Ctr Excellence Climate Change Res Dept Meteorol Jeddah 21589 Saudi Arabia

Knowledge of aerosol size and composition is very important for investigating the radiative forcing impacts of aerosols, distinguishing aerosol sources, and identifying harmful particulate types in air quality monitoring. The ability to identify aerosol type synoptically would greatly contribute to the knowledge of aerosol type distribution at both regional and global scales, especially where there are no data on chemical composition. In this study, aerosol classification techniques were based on aerosol optical properties from remotely-observed data from the Ozone Monitoring Instrument (OMI) and Aerosol Robotic Network (AERONET) over Saudi Arabia for the period 2004-2016 and validated using data from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO). For this purpose, the OMI-based Aerosol Absorption Optical Depth (AAOD) and UltraViolet Aerosol Index (UVAI), and AERONET-based AAOD, Angstrom Exponent (AE), Absorption Angstrom Exponent (AAE), Fine Mode Fraction (FMF), and Single Scattering Albedo (SSA) were obtained. Spatial analysis of the satellite-based OMI-AAOD showed the dominance of absorbing aerosols over the study area, but with high seasonal variability. The study found significant underestimation by OMI AAOD suggesting that the OMAERUV product may need improvement over bright desert surfaces such as the study area. aerosols were classified into (i) Dust, (ii) Black Carbon (BC), and (iii) Mixed (BC and Dust) based on the relationships technique, between the aerosol absorption properties (AAE, SSA, and UVAI) and size parameters (AE and FMF). Additionally, the AE vs. UVAI and FMF vs. UVAI relationships misclassified the aerosol types over the study area, and the FMF vs. AE, FMF vs. AAE and FMF vs. SSA relationships were found to be robust. As expected, the dust aerosol type was dominant both annually and seasonally due to frequent dust storm events. Also, fine particulates such as BC and Mixed (BC and Dust) were observed, likely d

关键词： aerosols AERONET Single scattering albedo Absorption angstrom exponent Ozone monitoring instrument Aerosol absorption optical depth

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Chemical composition of aerosols generated by heating prototypic fuel debris samples

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Science Talks 2023年 6卷

作者： Christophe Journeau Jules Delacroix Célia Guévar Véronique Testud Emmanuelle Brackx Emmanuel Porcheron Antonin Bouland Romain Berlemont Atsushi Ikeda-Ohno CEA DES IRESNE DTN SMTA Severe Accident Experimental Laboratory Cadarache F-13108 Saint-Paul-lez-Durance France CEA DES ISEC DMRC SASP Material Chemical Analyses and Characterization Laboratory Univ Montpellier Marcoule France Institut de Radioprotection et de Sûreté Nucléaire (IRSN) PSN-RES SCA 91192 Gif-sur-Yvette France ONET Technologies 26701 Pierrelatte France International Research Institute for Nuclear Decommissioning (IRID) / Japan Atomic Energy Agency (JAEA) Collaborative Laboratories for Advanced Decommissioning Science (CLADS) 2-4 Shirakata Tokai-mura Naka-gun Ibaraki 319-1194 Japan

One of the important challenges for the decommissioning of the damaged reactors of the Fukushima Daiichi Nuclear Power Station (1F) is the fuel debris retrieval. In this context, the URASOL (URAnium and aeroSOL) project has been undertaken by the French consortium laboratories consisting of ONET, CEA, and IRSN for JAEA/CLADS. It aims at acquiring basic data on the generation and characteristics of radioactive aerosols from the thermal or mechanical processing of fuel debris simulant. Prototypic fuel debris samples were fabricated at VULCANO facility based on the average of the lower head compositions computed in the OECD/BSAF benchmark. Samples were heated in the VITAE (aerosols configuration of the VITI facility) induction furnace to simulate thermal cutting (e.g. by laser) and released aerosols were collected during three temperature ramps using impactors. The collected aerosols were chemically analyzed by ICP-AES and ICP-MS. Overall, iron and tin are the major elements found in these aerosols, followed by chromium and silicon. Uranium contributes to 1.8 wt% of the measured elements. Significant releases of tellurium, barium and cerium were observed, mainly in ramp 1 (20–1800 °C). A significant variation of releases with temperature and with aerosol size class were also observed. Finally, comparison with a simulant fuel debris, in which hafnium replaced uranium mole by mole, confirmed that uranium is significantly more released than the simulant, emphasizing the interest of carrying out experiments with prototypic materials.

关键词： Fukushima Daiichi Fuel debris Cutting aerosols Material analyses

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Effects of mask-wearing on the inhalability and deposition of airborne SARS-CoV-2 aerosols in human upper airway

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PHYSICS OF FLUIDS 2020年第12期32卷 123312-123312页

作者： Xi, Jinxiang Si, Xiuhua April Nagarajan, Ramaswamy Univ Massachusetts Dept Biomed Engn 1 Univ Ave Lowell MA 01854 USA Calif Baptist Univ Dept Aerosp Ind & Mech Engn 8432 Magnolia Ave Riverside CA 92504 USA Univ Massachusetts Dept Plast Engn 1 Univ Ave Lowell MA 01854 USA Univ Massachusetts Fabr Discovery Ctr 110 Canal St Lowell MA 01852 USA

Even though face masks are well accepted as tools useful in reducing COVID-19 transmissions, their effectiveness in reducing viral loads in the respiratory tract is unclear. Wearing a mask will significantly alter the airflow and particle dynamics near the face, which can change the inhalability of ambient particles. The objective of this study is to investigate the effects of wearing a surgical mask on inspiratory airflow and dosimetry of airborne, virus-laden aerosols on the face and in the respiratory tract. A computational model was developed that comprised a pleated surgical mask, a face model, and an image-based upper airway geometry. The viral load in the nose was particularly examined with and without a mask. Results show that when breathing without a mask, air enters the mouth and nose through specific paths. When wearing a mask, however, air enters the mouth and nose through the entire surface of the mask at lower speeds, which favors the inhalation of ambient aerosols into the nose. With a 65% filtration efficiency (FE) typical for a three-layer surgical mask, wearing a mask reduces dosimetry for all micrometer particles except those of size 1 mu m-3 mu m, for which equivalent dosimetry with and without a mask in the upper airway was predicted. Wearing a mask reduces particle penetration into the lungs, regardless of the FE of the mask. The results also show that mask-wearing protects the upper airway (particularly the nose and larynx) best from particles larger than 10 mu m while protecting the lungs best from particles smaller than 10 mu m.

关键词： aerosols

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Tropical Belt Width Proportionately More Sensitive to aerosols Than Greenhouse Gases

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GEOPHYSICAL RESEARCH LETTERS 2020年第7期47卷 e2019GL086425-e2019GL086425页

作者： Zhao, Xueying Allen, Robert J. Wood, Tom Maycock, Amanda C. Univ Calif Riverside Dept Earth & Planetary Sci Riverside CA 92521 USA Univ Leeds Sch Earth & Environm Leeds W Yorkshire England

The tropical belt has widened during the last several decades, and both internal variability and anthropogenic forcings have contributed. Although greenhouse gases and stratospheric ozone depletion have been implicated as primary anthropogenic drivers of tropical expansion, the possible role of other drivers remains uncertain. Here, we analyze the tropical belt width response to idealized perturbations in multiple models. Our results show that absorbing black carbon (BC) aerosol drives tropical expansion, and scattering sulfate aerosol drives contraction. BC, especially from Asia, is more efficient per unit radiative forcing than greenhouse gases in driving tropical expansion, particularly in the Northern Hemisphere. Tropical belt expansion (contraction) is associated with an increase (decrease) in extratropical static stability induced by absorbing (scattering) aerosol. Although a formal attribution is difficult, scaling the normalized expansion rates to the historical time period suggests that BC is the largest driver of the Northern Hemisphere tropical widening but with relatively large uncertainty. Plain Language Summary The tropical belt has widened over the past several decades, and this is associated with poleward movement of the descending branches of the Hadley Cell and the subtropical dry zones. Internal climate variability and anthropogenic forcers-including greenhouse gases and stratospheric ozone depletion-are important contributors. Leveraging idealized single-forcing experiments, we show that anthropogenic aerosols, including black carbon and sulfate, drive significant tropical expansion and contraction, respectively. aerosols, particularly those emitted from Asia, are more efficient than greenhouse gases in perturbing tropical belt width. Although relatively large uncertainty exists, linearized scaling suggests that black carbon is the dominant driver of the Northern Hemisphere tropical widening over the historical time period.

关键词： tropical belt width anthropogenic drivers greenhouse gases aerosols PDRMIP

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Evaluation of sea salt aerosols in climate systems: global climate modeling and observation-based analyses*

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ENVIRONMENTAL RESEARCH LETTERS 2020年第3期15卷

作者： Chen, Yi-Chun Li, Jui-Lin F. Lee, Wei-Liang Diner, David J. Garay, Michael J. Jiang, Jonathan H. Wang, Yi-Hui Yu, Jia-Yuh Kalashnikova, Olga, V Acad Sinica Res Ctr Environm Changes Taipei Taiwan CALTECH Jet Prop Lab Pasadena CA USA Calif Polytech State Univ San Luis Obispo San Luis Obispo CA 93407 USA Natl Cent Univ Dept Atmospher Sci Taoyuan Taiwan

Sea salt aerosols (SSA), one of the most abundant aerosol species over the global oceans, play important roles for Earth's climate. State-of-the-art SSA parameterizations in global climate models (GCMs) are typically modeled using near-surface wind speed, sea surface temperature (SST), and precipitation. However, these have non-trivial biases in CMIP3 and CMIP5 GCMs over the tropical Pacific Ocean that can contribute to biases in the simulated SSA. This study investigates the impacts of falling ice radiative effects on the biases of the aforementioned modeled parameters and the resulting modeled SSA biases. We compare the CMIP5 modeled SSA against satellite observations from MISR and MODIS using a pair of sensitivity experiments with falling ice radiative effects on and off in the CESM1-CAM5 model. The results show that when falling ice radiative effects are not taken into account, models have weaker surface wind speeds, warmer SSTs, excessive precipitation, and diluted sea surface salinity (SSS) over the Pacific trade-wind regions, leading to underestimated SSA. In the tropical Pacific Ocean, the inclusion of falling ice radiative effects leads to improvements in the modeled near-surface wind speeds, SSTs, and precipitation through cloud-precipitation-radiation-circulation coupling, which results in more representative patterns of SSA and reduces the SSA biases by similar to 10% to 15% relative to the satellite observations. Models including falling ice radiative effects in CMIP5 produce smaller biases in SSA than those without falling ice radiative effects. We suggest that one of the causes of these biases is likely the failure to account for falling ice radiative effects, and these biases in turn affect the direct and indirect effects of SSA in the GCMs.

关键词： global climate modeling aerosols sea salt falling ice radiative effects

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Editorial for Special Issue "High Resolution Active Optical Remote Sensing Observations of aerosols, Clouds and Aerosol-Cloud Interactions and Their Implication to Climate"

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REMOTE SENSING 2020年第13期12卷 2166页

作者： Lolli, Simone Qin, Kai Campbell, James R. Wang, Sheng-Hsiang CNR IMAA I-85050 Tito PZ Italy Kent State Univ Dept Phys Florence Campus Kent OH 44240 USA CUMT Sch Environm Sci & Spatial Informat Xuzhou 221116 Jiangsu Peoples R China Naval Res Lab Monterey CA 93943 USA Natl Cent Univ Dept Atmospher Sci Taoyuan 32001 Taiwan

This Special Issue contains twelve publications that, through different remote sensing techniques, investigate how the atmospheric aerosol layers and their radiative effects influence cloud formation, precipitation and air-quality. The investigations are carried out analyzing observations obtained from high-resolution optical devices deployed on different platforms as satellite and ground-based observational sites. In this editorial, the published contributions are taken in review to highlight their innovative contribution and research main findings.

关键词： lidar aerosols remote sensing precipitation wind lidar air-pollution radiative effects

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Characteristics of microbial activity in atmospheric aerosols and its relationship to chemical composition of PM2.5 in Xian, China

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JOURNAL OF AEROSOL SCIENCE 2020年 146卷 105572-105572页

作者： Wang, Beibei Li, Yanpeng Xie, Zhengsheng Du, Shengli Zeng, Xuelin Hou, Junli Ma, Tianfeng Changan Univ Sch Water & Environm Xian 710054 Peoples R China Minist Educ Key Lab Subsurface Hydrol & Ecol Arid Areas Xian 710054 Peoples R China

Microbial activity levels in atmospheric aerosols can affect human health, and ecosystem and atmospheric processes. However, information on the influence of microbial activity in atmospheric aerosols remains very limited. In this study, the characteristics of microbial activity in atmospheric aerosols in Xi'an, China, were determined using the fluorescein diacetate hydrolysis method. The influences of meteorological factors, height and water-soluble inorganic ions on microbial activity were examined. The results indicate that the levels of the atmospheric inorganic ions increased as the air quality index (AQI) increased. The microbial activity and concentration of PM2.5 were significantly positively correlated during sampling period (p < 0.05). Notably, microbial activity levels in PM2.5 and PM10 both increased with the AQI and decreased from ground level to 228 m. Additionally, higher microbial activity levels were detected during floating dust events and lower levels were found during periods of rainfall. Among the nine inorganic ions, microbial activity was significantly positively correlated with Nathorn, Mg-2+ and Ca2+ (p < 0.05). Correlation results indicate that microbial activity was greatly influenced by soil source in spring and summer. The present results improve our understanding of the correlations between airborne microbes and atmospheric chemical composition.

关键词： aerosols Microbial activity Chemical composition PM2.5 PM10

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Sporadic increases of radioactive aerosols as a possible reason for heavy nuclides enhancements recorded with the en-detectors

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JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2020年 222卷 106335-106335页

作者： Stenkin, Yu, V Alekseenko, V. V. Dzhappuev, D. D. Kuleshov, D. A. Kudjaev, A. U. Levochkin, K. R. Mikhailova, O., I Shchegolev, O. B. Stepanov, V., I Russian Acad Sci Inst Nucl Res Moscow Russia Natl Res Nucl Univ MEPhi Moscow Russia

Some unexpected sporadic increases of an environmental radioactive background have been recorded at mountain level at Baksan Neutrino Observatory (BNO, 1700 m above sea level) using electron-neutron detectors (en-detectors), which could be explained by radioactive aerosol enhancements. The large area inorganic scintillator en-detectors developed for cosmic ray study are continuously monitoring environmental thermal neutron fluxes at various geophysical conditions. Application of the pulse shape discrimination method allows us to select and separately measure both thermal neutrons and radioactive beta-decay nuclides being products of radon decays in air (mostly Rn-222 and Rn-220). There are two en-detector setups running now at BNO, one deep underground while another one at surface. Both installations had recorded some strange sporadic increases of radioactive nuclides in air. In this paper, we present results and the most probable explanation of the significant increases joint by radioactive aerosols production but caused by different reasons: Baksan river floods or nearby underground experiment with powerful Cr-51 radioactive source.

关键词： Radioactivity Radon en-detector aerosols

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Transport of Asian aerosols to the Pacific Ocean

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ATMOSPHERIC RESEARCH 2020年 234卷 104735-000页

作者： Zhu, Qingzhe Liu, Yuzhi Shao, Tianbin Tang, Yuhan Lanzhou Univ Coll Atmospher Sci Key Lab Semiarid Climate Change Minist Educ Lanzhou 730000 Peoples R China

Recent efforts reported that the aerosols even can be transported from a long distance to the Pacific Ocean (PO) and potentially influence the marine primary productivity. In this study, based on the multi-source satellite observations and meteorological reanalysis data, the source and transport of aerosols from Asia to the PO region are investigated. The result shows that the satellites capture 104 aerosol events during 2007-2016, which occur in Asia, and can further influence the PO region. The Asian source regions of aerosol over the PO region mainly include eastern and central China (ECC), eastern and central Russia (ECR), Inner Mongolia and Gansu of China and Mongolia (IMGM), and Southeast Asia (SEA), corresponding to sulfate, organic carbon, dust, and organic carbon aerosol sources, respectively. Among the aerosol events detected over the PO region, most of them are sourced from ECC region, accounting for 54.8% of the total aerosol events, followed by ECR region (accounting for 22.1%). Statistical analyses show that, during 2007-2016, the aerosol events observed over the PO region mainly occur in the spring (47 times), followed by the autumn (25 times);and the least of them occur in the winter (14 times). Correspondingly, the months with the most and least aerosol events are March and February, respectively. When the aerosols enter the PO region, the average optical depths of aerosols sourcing from ECC, ECR, IMGM and SEA are 0.24, 0.38, 0.29 and 0.19, respectively. Besides, the transport of aerosols from Asia to the PO region is mainly influenced by westerly winds and troughs of low-pressure system. This study can provide some evidence of understanding the aerosol type, physical and optical properties over the PO region.

关键词： aerosols Transport Asia The Pacific Ocean

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