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Vertical distributions and columnar properties of the aerosols during different seasons over Kattankulathur (12.82°N, 80.04°E): A semi-urban tropical coastal station

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ATMOSPHERIC ENVIRONMENT 2021年 256卷 118457-118457页

作者： Ananthavel, Aravindhavel Mehta, Sanjay Kumar Reddy, T. V. Ramesh Ali, Saleem Rao, D. Narayana SRM Inst Sci & Technol Res Inst Kattankulathur 603203 Tamil Nadu India SRM Univ Amaravati 522502 Andhra Pradesh India

Seasonal characteristics of the aerosols over Kattankulathur (12.83 degrees N, 80.04 degrees E) is studied using Micro Pulse Lidar observations during 2016-2018 and Cloud Aerosol Lidar and Infrared Pathfinder Satellite Observation, Moderate Resolution Imaging Spectroradiometer and Ozone Monitoring Instrument datasets during 2006-2018. The vertical distribution of the aerosols is characterized as the steep decrease with altitude nearly exponentially up to 2-3 km during the northeast (NE) monsoon and winter seasons mainly dominated by clear marine and polluted continental aerosols. While it gradually decreases with altitude up to 4-5 km during pre-monsoon and southwest monsoon (SW) seasons mainly dominated by dust aerosols. The mean aerosol loadings near the surface are similar to 0.38 km(-1) during NE monsoon and winter, similar to 0.30 km(-1) pre-monsoon, and 0.22 km(-1) during SW monsoon seasons. Such difference in the seasonal distribution of aerosol loading is mainly attributed to the difference in surface insolation, convection, long-range transport, and the atmospheric boundary layer (ABL) structure and dynamics. The ABL contributes 61%, 46%, 38%, and 63% of the overall aerosol optical depth (AOD) during the winter, pre-monsoon, SW monsoon, and NE monsoon seasons, respectively. The AOD shows a substantial seasonal variation with two local maxima during May and October and minima during January and July. The maximum and minimum AOD is found to be similar to 0.59 +/- 0.16 and 0.4 +/- 0.05, respectively. The Angstrom exponent (AE) (fine mode fraction (FMF)) shows a marked seasonal variation with a maximum value of 0.84 (0.60), indicating the dominance of finer particles during winter and minimum value of 0.54 (0.27), indicating dominance coarse particles during SW monsoon. The AE and UV aerosol index values suggest that Kattankulathur is mainly characterized by large-sized absorbing aerosols (30%) such as dust mixture and sea salt particles. Smallsized non-absorbi

关键词： aerosols North-east monsoon region Pollution Lidar

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A new technique for real-time measurements of potassium and sodium aerosols based on field-reversal surface ionization

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MEASUREMENT SCIENCE AND TECHNOLOGY 2021年第7期32卷

作者： Gall, Dan Nejman, Charlotta Allguren, Thomas Andersson, Klas Pettersson, Jan B. C. Univ Gothenburg Dept Chem & Mol Biol Gothenburg Sweden Chalmers Univ Technol Dept Space Earth & Environm Gothenburg Sweden

A new method for real-time measurements of potassium and sodium containing aerosol particles is described and verified. The method is based on surface ionization technique and may be used to explore the alkali chemistry related to high temperature chemistry processes. The measurement device is a further development of the simple and cost-effective surface ionization detector previously used for online alkali measurements in combustion and gasification research. The discrimination between sodium and potassium is possible due to differences in their surface desorption kinetics and facilitated by rapidly reversing the field potential between the ion source and the nearby collector. The instrument is evaluated in a series of laboratory experiments using size-selected alkali salt particles containing KCl, NaCl, K2SO4, Na2SO4, KNO3 and NaNO3. The filament temperature was found to be a key influencing factor in order to optimize the strength and Na-K deviation of the observed ion current. The ability to simultaneously report absolute concentrations of Na and K makes the instrument attractive for solid fuel conversion of alkali-rich fuels such as low-grade biomass and to explore behavior deviations of Na and K in high temperature processes.

关键词： alkali aerosols ionization combustion corrosion

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Effect of Vertical Profile of aerosols on the Local Shortwave Radiative Forcing Estimation

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ATMOSPHERE 2021年第2期12卷 187页

作者： Molero, Francisco Fernandez, Alfonso Javier Revuelta, Maria Aranzazu Martinez-Marco, Isabel Pujadas, Manuel Artinano, Begona Ctr Invest Energet Medioambientales & Tecnol CIEM Dept Environm Avda Complutense 40 Madrid 28040 Spain Agencia Estatal Meteorol AEMET C Leonardo Prieto Castro 8 Madrid 28071 Spain

In this work, the effect of the aerosol vertical distribution on the local shortwave aerosol radiative forcing is studied. We computed the radiative forcing at the top and bottom of the atmosphere between 0.2 and 4 microns using the libRadTran package and compared the results with those provided by AERONET (AErosol RObotic NETwork). Lidar measurements were employed to characterize the aerosol vertical profile, and collocated AERONET measurements provided aerosol optical parameters required to calculate its radiative forcing. A good correlation between the calculated radiative forcings and those provide by AERONET, with differences smaller than 1 W m(-2) (15% of estimated radiative forcing), is obtained when a gaussian vertical aerosol profile is assumed. Notwithstanding, when a measured aerosol profile is inserted into the model, differences between radiative forcings can vary up to 6.54 W m(-2) (15%), with a mean of differences = -0.74 +/- 3.06 W m(-2) at BOA and -3.69 W m(-2) (13%), with a mean of differences = -0.27 +/- 1.32 W m(-2) at TOA due to multiple aerosol layers and aerosol types. These results indicate that accurate information about aerosol vertical distribution must be incorporated in the radiative forcing calculation in order to reduce its uncertainties.

关键词： aerosols radiative forcing lidar vertical profile libRadTran

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Spread of virus laden aerosols inside a moving sports utility vehicle with open windows: A numerical study

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PHYSICS OF FLUIDS 2021年第9期33卷 095117-095117页

作者： Sen, Nirvik Singh, K. K. Bhabha Atom Res Ctr Chem Engn Div Mumbai 400085 Maharashtra India Homi Bhabha Natl Inst Mumbai 400094 Maharashtra India

A three dimensional Computational Fluid Dynamics (CFD) model to study the dispersion of virus laden aerosols in a car moving with its windows open is reported. The aerosols are generated when a possibly infected passenger speaks. A sports utility vehicle having three rows of seats has been considered. As the vehicle moves forward, its interior will exchange air from the surroundings. The CFD model captures the flow patterns generated both outside and inside the vehicle. This internal aerodynamics will in turn dictate how aerosols will spread across the interior and whether or not they will be transported outside the vehicle. A Lagrangian approach is used to determine the transport of the aerosol particles and the effect of particle size on the simulation result has been studied. Four sets of scenarios of practical interest have been considered. The first set shows the effect of vehicle speed on aerosol transport, and the second set describes what happens when some of the windows are closed, while the third set describes how aerosol transport is affected by the location of the passenger speaking. The fourth set describes how a gush of cross wind affects aerosol transport. Simulation results reveal that when all windows are open, aerosols can go out of one window and then return back to the vehicle interior through another window. Results also reveal that when a passenger sitting in the second row speaks, the aerosols generated span across the entire volume of the car interior before going out through the open windows. Published under an exclusive license by AIP Publishing. https://***/10.1063/5.0061753

关键词： aerosols

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Vertical Distribution of aerosols during Deep-Convective Event in the Himalaya Using WRF-Chem Model at Convection Permitting Scale

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ATMOSPHERE 2021年第9期12卷 1092页

作者： Singh, Prashant Sarawade, Pradip Adhikary, Bhupesh Univ Mumbai Dept Phys Mumbai 400098 Maharashtra India Int Ctr Integrated Mt Dev ICIMOD Khumaltar G POB 3226 Lalitpur 44700 Nepal

The Himalayan region is facing frequent cloud bursts and flood events during the summer monsoon season. The Kedarnath flooding of 2013 was one of the most devastating recent events, which claimed thousands of human lives, heavy infrastructure, and economic losses. Previous research reported that the combination of fast-moving monsoon, pre-existing westerlies, and orographic uplifting were the major reasons for the observed cloud burst over Kedarnath. Our study illustrates the vertical distribution of aerosols during this event and its possible role using the Weather Research and Forecasting model coupled with chemistry (WRF-Chem) simulations. Model performance evaluation shows that simulations can capture the spatial and temporal patterns of observed precipitation during this event. Model simulation at 25 km and 4 km horizontal grid resolution, without any changes in physical parameterization, shows a very minimal difference in precipitation. Simulation at convection-permitting scale shows detailed information related to parcel motion compared to coarser resolution. This indicates that the parameterization at different resolutions needs to be further examined for a better outcome. The modeled result shows changes of up to 20-50% in the rainfall over the area near Kedarnath due to the presence of aerosols. Simulation at both resolutions shows the significant vertical transport of natural (increases by 50%+) and anthropogenic aerosols (increases by 200%+) during the convective event, which leads to significant changes in cloud properties, rain concentration, and ice concentration in the presence of these aerosols. Simulations can detect changes in important instability indices such as convective available potential energy (CAPE), convective inhibition energy (CIN), vorticity, etc., near Kedarnath due to aerosol-radiation feedback.

关键词： aerosols South Asia WRF-Chem precipitation CAPE CIN

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Disease transmission through expiratory aerosols on an urban bus

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PHYSICS OF FLUIDS 2021年第1期33卷 015116-015116页

作者： Zhang, Zhihang Han, Taehoon Yoo, Kwang Hee Capecelatro, Jesse Boehman, Andre L. Maki, Kevin Univ Michigan Dept Naval Architecture & Marine Engn 138 NAME Bldg2600 Draper Dr Ann Arbor MI 48109 USA Univ Michigan Dept Mech Engn 2045 AL WE Lay Auto Lab1231 Beal Ann Arbor MI 48109 USA Univ Michigan Dept Mech Engn 2011 AL WE Lay Auto Lab1231 Beal Ann Arbor MI 48109 USA Univ Michigan Dept Naval Architecture & Marine Engn 210 NAME Bldg2600 Draper Dr Ann Arbor MI 48109 USA Univ Michigan Dept Aerosp Engn Ann Arbor MI 48109 USA

Airborne respiratory diseases such as COVID-19 pose significant challenges to public transportation. Several recent outbreaks of SARS-CoV-2 indicate the high risk of transmission among passengers on public buses if special precautions are not taken. This study presents a combined experimental and numerical analysis to identify transmission mechanisms on an urban bus and assess strategies to reduce risk. The effects of the ventilation and air-conditioning systems, opening windows and doors, and wearing masks are analyzed. Specific attention is paid to the transport of submicron- and micron-sized particles relevant to typical respiratory droplets. High-resolution instrumentation was used to measure size distribution and aerosol response time on a campus bus of the University of Michigan under these different conditions. Computational fluid dynamics was employed to measure the airflow within the bus and evaluate risk. A risk metric was adopted based on the number of particles exposed to susceptible passengers. The flow that carries these aerosols is predominantly controlled by the ventilation system, which acts to uniformly distribute the aerosol concentration throughout the bus while simultaneously diluting it with fresh air. The opening of doors and windows was found to reduce the concentration by approximately one half, albeit its benefit does not uniformly impact all passengers on the bus due to the recirculation of airflow caused by entrainment through windows. Finally, it was found that well fitted surgical masks, when worn by both infected and susceptible passengers, can nearly eliminate the transmission of the disease.

关键词： aerosols

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The Impact of aerosols on Satellite Radiance Data Assimilation Using NCEP Global Data Assimilation System

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ATMOSPHERE 2021年第4期12卷 432页

作者： Wei, Shih-Wei Lu, Cheng-Hsuan (Sarah) Liu, Quanhua Collard, Andrew Zhu, Tong Grogan, Dustin Li, Xu Wang, Jun Grumbine, Robert Bhattacharjee, Partha S. SUNY Albany Atmospher Sci Res Ctr Albany NY 12222 USA Joint Ctr Satellite Data Assimilat Boulder CO 80301 USA NOAA NESDIS Ctr Satellite Applicat & Res College Pk MD 20740 USA NCEP NWS EMC IM Syst Grp College Pk MD 20740 USA NOAA NESDIS STAR IM Syst Grp College Pk MD 20740 USA NOAA NWS Natl Ctr Environm Predict College Pk MD 20740 USA

Aerosol radiative effects have been studied extensively by climate and weather research communities. However, aerosol impacts on radiance in the context of data assimilation (DA) have received little research attention. In this study, we investigated the aerosol impacts on the assimilation of satellite radiances by incorporating time-varying three-dimensional aerosol distributions into the radiance observation operator. A series of DA experiments was conducted for August 2017. We assessed the aerosol impacts on the simulated brightness temperatures (BTs), bias correction and quality control (QC) algorithms for the assimilated infrared sensors, and analyzed temperature fields. We found that taking the aerosols into account reduces simulated BT in thermal window channels (8 to 13 mu m) by up to 4 K over dust-dominant regions. The cooler simulated BTs result in more positive first-guess departures, produce more negative biases, and alter the QC checks about 20%/40% of total/assimilated observations at the wavelength of 10.39 mu m. As a result, assimilating aerosol-affected BTs produces a warmer analyzed lower atmosphere and sea surface temperature which have better agreement with measurements over the trans-Atlantic region.

关键词： aerosols data assimilation satellite radiance thermal infrared atmospheric window

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Performance and economic analyses of a combined bioreactor for treating odors, volatile organic compounds, and aerosols from a landfill site

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JOURNAL OF CLEANER PRODUCTION 2021年 278卷 124161-124161页

作者： Liu, Jianwei Lu, Chen Huang, Lihua Sun, Jianbin Yue, Peng Liu, Xueli Kang, Xinyue Beijing Univ Civil Engn & Architecture Beijing Res Ctr Sustainable Urban Drainage Syst & Beijing 100044 Peoples R China Linyi Univ Sch Resources & Environm Linyi 276005 Shandong Peoples R China Beijing Univ Civil Engn & Architecture Dept Environm Sci & Engn Beijing 100044 Peoples R China 1 Zhanlan Rd Beijing 100044 Peoples R China Middle Part Shuangling Rd Linyi 276005 Shandong Peoples R China

A full-scale combined bioreactor with a biological aeration zone (BAZ) and a biological filtration zone (BFZ) was adopted to treat odors, volatile organic compounds (VOCs), and aerosols emitted from a landfill site. The BAZ mainly relies on suspended microorganisms that degrade substances with high water solubility, while the BFZ is divided into an acidic biofiltration unit (ABU) and a neutral biofiltration unit (NBU) to further remove remaining contaminants. Average removal efficiencies (REs) of 97.21%, 98.89%, 92.44%, 73.12%, and 81.89% for H2S, NH3, VOCs, culturable bacteria, and fungi, respectively, were achieved during the stable operation period. In particular, the concentrations of water-soluble ions (WSIs), including SO42-, NO2-, NO3-, and Cl- in aerosols, were significantly reduced by the combined bioreactor. The REs and degradation product characteristics for the odors, VOCs, and aerosols in the BAZ and BFZ were different due to different dominant microorganisms. In addition, the economic cost of the combined bioreactor was analyzed considering investment cost, operating cost, and packing material replacement cost, and a sensitivity analysis was performed to determine economically-sensitive parameters. This study clearly demonstrates the low cost and effectiveness of the combined bioreactor to treat exhaust gases containing odors, VOCs, and aerosols from a landfill site. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： Odors Combined bioreactor Biological aeration zone Biological filtration zone aerosols

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ATmospheric LIDar (ATLID): Pre-Launch Testing and Calibration of the European Space Agency Instrument That Will Measure aerosols and Thin Clouds in the Atmosphere

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ATMOSPHERE 2021年第1期12卷 76页

作者： do Carmo, Joao Pereira de Villele, Geraud Wallace, Kotska Lefebvre, Alain Ghose, Kaustav Kanitz, Thomas Chassat, Francois Corselle, Bertrand Belhadj, Thomas Bravetti, Paolo European Space Agency ESTEC NL-2200 AG Noordwijk Netherlands Airbus Def & Space F-31402 Toulouse 4 France

ATLID (ATmospheric LIDar) is the atmospheric backscatter Light Detection and Ranging (LIDAR) instrument on board of the Earth Cloud, Aerosol and Radiation Explorer (EarthCARE) mission, the sixth Earth Explorer Mission of the European Space Agency (ESA) Living Planet Programme. ATLID's purpose is to provide vertical profiles of optically thin cloud and aerosol layers, as well as the altitude of cloud boundaries, with a resolution of 100 m for altitudes of 0 to 20 km, and a resolution of 500 m for 20 km to 40 km. In order to achieve this objective ATLID emits short duration laser pulses in the ultraviolet, at a repetition rate of 51 Hz, while pointing in a near nadir direction along track of the satellite trajectory. The atmospheric backscatter signal is then collected by its 620 mm aperture telescope, filtered through the optics of the instrument focal plane assembly, in order to separate and measure the atmospheric Mie and Rayleigh scattering signals. With the completion of the full instrument assembly in 2019, ATLID has been subjected to an ambient performance test campaign, followed by a successful environmental qualification test campaign, including performance calibration and characterization in thermal vacuum conditions. In this paper the design and operational principle of ATLID is recalled and the major performance test results are presented, addressing the main key receiver and emitter characteristics. Finally, the estimated instrument, in-orbit, flight predictions are presented;these indicate compliance of the ALTID instrument performance against its specification and that it will meet its mission science objectives for the EarthCARE mission, to be launched in 2023.

关键词： LIDAR UV laser high spectral resolution aerosols

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Strong Local Evaporative Cooling Over Land Due to Atmospheric aerosols

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JOURNAL OF ADVANCES IN MODELING EARTH SYSTEMS 2021年第5期13卷 e2021MS002491-e2021MS002491页

作者： Chakraborty, T. C. Lee, Xuhui Lawrence, David M. Yale Univ Sch Environm New Haven CT 06520 USA Natl Ctr Atmospher Res POB 3000 Boulder CO 80307 USA

aerosols can enhance terrestrial productivity through increased absorption of solar radiation by the shaded portion of the plant canopy-the diffuse radiation fertilization effect. Although this process can, in principle, alter surface evaporation due to the coupling between plant water loss and carbon uptake, with the potential to change the surface temperature, aerosol-climate interactions have been traditionally viewed in light of the radiative effects within the atmosphere. Here, we develop a modeling framework that combines global atmosphere and land model simulations with a conceptual diagnostic tool to investigate these interactions from a surface energy budget perspective. aerosols increase the terrestrial evaporative fraction, or the portion of net incoming energy consumed by evaporation, by over 4% globally and as much as similar to 40% regionally. The main mechanism for this is the increase in energy allocation from sensible to latent heat due to global dimming (reduction in global shortwave radiation) and slightly augmented by diffuse radiation fertilization. In regions with moderately dense vegetation (leaf area index >2), the local surface cooling response to aerosols is dominated by this evaporative pathway, not the reduction in incident radiation. Diffuse radiation fertilization alone has a stronger impact on gross primary productivity (+2.18 Pg C y(-1) or +1.8%) than on land evaporation (+0.18 W m(-2) or +0.48%) and surface temperature (-0.01 K). Our results suggest that it is important for land surface models to distinguish between quantity (change in total magnitude) and quality (change in diffuse fraction) of radiative forcing for properly simulating surface climate.

关键词： aerosols atmosphere-biosphere interactions diffuse radiation fertilization effect earth system modeling evapotranspiration global land model gross primary productivity surface energy budget surface temperature

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