Increase In Aerosol Concentration Research Articles

Processes Controlling the Entrainment and Liquid Water Response to Aerosol Perturbations in Non-Precipitating Stratocumulus Clouds

Abstract It has been widely reported that an increase in aerosol concentration in non-precipitating clouds leads to a decrease in their liquid water path. Here we examine the physical mechanisms that drive this response in both subtropical and Arctic stratocumulus clouds using large eddy simulations and mechanism suppression tests. Three processes have been previously identified to contribute to the decrease, namely, the size-dependency of evaporation, sedimentation, and radiation and all act to modulate the rate of entrainment of warm, dry air at the boundary layer top. We find that the liquid water path decrease is correlated with the increased entrainment, as expected, but that the decrease is enhanced by a reduction in cloud radiative cooling. The reduced cloud radiative cooling can occur even though locally at cloud top the radiative cooling rates are stronger and helping to enhance entrainment. We find that slower droplet sedimentation contributes to the increased entrainment and decreased liquid water in both cases. Faster evaporation caused directly by smaller, more numerous droplets decreases the liquid water path but does not necessarily increase the entrainment rate. On the other hand, stronger radiative cloud top cooling caused directly by smaller droplets increases the entrainment as much as slower sedimentation does but does not decrease the liquid water path as much. In general, processes that either directly or indirectly increase radiative cooling at cloud top are more important in the Arctic case and processes that increase the evaporation rate are more important in the subtropical case.

Processes Controlling the Entrainment and Liquid Water Response to Aerosol Perturbations in Non-Precipitating Stratocumulus Clouds

Abstract It has been widely reported that an increase in aerosol concentration in non-precipitating clouds leads to a decrease in their liquid water path. Here we examine the physical mechanisms that drive this response in both subtropical and Arctic stratocumulus clouds using large eddy simulations and mechanism suppression tests. Three processes have been previously identified to contribute to the decrease, namely, the size-dependency of evaporation, sedimentation, and radiation and all act to modulate the rate of entrainment of warm, dry air at the boundary layer top. We find that the liquid water path decrease is correlated with the increased entrainment, as expected, but that the decrease is enhanced by a reduction in cloud radiative cooling. The reduced cloud radiative cooling can occur even though locally at cloud top the radiative cooling rates are stronger and helping to enhance entrainment. We find that slower droplet sedimentation contributes to the increased entrainment and decreased liquid water in both cases. Faster evaporation caused directly by smaller, more numerous droplets decreases the liquid water path but does not necessarily increase the entrainment rate. On the other hand, stronger radiative cloud top cooling caused directly by smaller droplets increases the entrainment as much as slower sedimentation does but does not decrease the liquid water path as much. In general, processes that either directly or indirectly increase radiative cooling at cloud top are more important in the Arctic case and processes that increase the evaporation rate are more important in the subtropical case.

Flipping of temperature and precipitation trends over the Indian subcontinent due to diametrically opposing influence of GHGs and aerosols

Despite significant development in the Earth system models (ESMs) and releases of several coupled model intercomparison projects (CMIPs), the evolving patterns of Indian summer monsoon rainfall and its future trajectory is still uncertain, with low confidence in its direction. This could be because of differential impacts from increasing greenhouse gas (GHG) and aerosol concentrations. We found that the observed pre-2000 (1951–2000) declining monsoon was likely attributed to the increasing aerosol concentrations. On the contrary, the reported revival of post-2000 monsoon rainfall is due to GHG dominance. These are spatiotemporally consistent with individual CMIP Phase 6 (CMIP6) ESM simulations with GHG and aerosols separately. Similar results were obtained for temperature in India, which showed no to low warming signal in pre-2000 due to aerosol-driven cooling. The dominance of GHG impacts has increased India’s warming trend in post-2000. This research highlights a notable trend in temperature and precipitation across the Indian subcontinent during the past two decades, emphasizing the dynamic character of climate change explained by contrasting anthropogenic influences, including GHGs and aerosols.

Anthropogenic warming degrades spring air quality in Northeast Asia by enhancing atmospheric stability and transboundary transport

Air pollutants can travel long distances from their sources, often causing severe particulate matter (PM) pollution in downwind regions. This transboundary pollution is largely influenced by meteorology and hence its changes associated with climate change. However, the effects of anthropogenic warming on transboundary pollution remain unclear. We show that springtime PM pollution can worsen with anthropogenic warming not only in the upwind region (northern China) but also in the downwind regions (South Korea and southern Japan). The worse air quality in northern China is attributed to a shallower boundary layer due to warmer air advection in the upper levels from high-latitude Eurasia and thus increased atmospheric stability. In the downwind regions, enhanced westerly/southwesterly anomalies induced by anthropogenic warming strengthen transboundary transport. The increase in primary aerosol concentrations due to the shallower boundary layer and/or enhanced transboundary transport is ~14% in northern China, ~13% in South Korea, and ~17% in southern Japan. The elevated relative humidity due to enhanced moisture transport by the wind anomalies promotes secondary aerosol formation, which further degrades the air quality in the downwind regions. The enhancement ratio of secondary aerosols relative to changes in primary aerosols is ~1 in northern China, ~1.12 in South Korea, and ~1.18 in southern Japan due to anthropogenic warming.

A simple and realistic aerosol emission approach for use in the Thompson–Eidhammer microphysics scheme in the NOAA UFS Weather Model (version GSL global-24Feb2022)

Abstract. A physics suite under development at NOAA's Global Systems Laboratory (GSL) includes the aerosol-aware double-moment Thompson–Eidhammer microphysics (TH-E MP) scheme. This microphysics scheme uses two aerosol variables (concentrations of water-friendly aerosol (WFA) and ice-friendly aerosol (IFA) numbers) to include interactions with some of the physical processes. In the original implementation, WFA and IFA depended on emissions derived from climatologies. In our approach, using the Common Community Physics Package (CCPP), we embedded modules of sea-salt emissions, dust emissions, and biomass-burning emissions, as well as of anthropogenic aerosol emissions, into the Unified Forecast System (UFS) to provide realistic aerosol emissions for these two variables. This represents a very simple approach with no additional tracer variables and therefore very limited additional computing cost. We then evaluated a comparison of simulations using the original TH-E MP approach, which derives the two aerosol variables using empirical emission formulas from climatologies (CTL) and simulations that use the online emissions (EXP). Aerosol optical depth (AOD) was derived from the two variables and appears quite realistic in the runs with online emissions when compared to analyzed fields. We found less resolved precipitation over Europe and North America from the EXP run, which represents an improvement compared to observations. Also interesting are moderately increased aerosol concentrations over the Southern Ocean from the EXP run, which invigorate the development of cloud water and enhance the resolved precipitation in those areas. This study shows that a more realistic representation of aerosol emissions may be useful when using double-moment microphysics schemes.

Comparisons of aerosol generation across different musical instruments and loudness

Respiratory aerosols can serve as vectors for disease transmission, and aerosol emission is highly activity-dependent. COVID-19 severely impacted the performing arts due to concerns about disease spread by respiratory aerosols and droplets generated during singing and playing musical instruments. Aerosol generation from woodwind and brass performance is less understood compared to singing due to uncertainty about how the diverse range of musical instruments may impact respiratory aerosol concentrations and size distributions. Here, aerosol number and mass concentrations along with size distributions were measured for breathing, speaking, and playing four different woodwind and brass instruments by 23 professional instrumentalists. We find that a 1 dBA increase in sound pressure level corresponds to a ∼10% increase in aerosol number concentration. The aerosol size distribution is consistent with that of breathing. Differences in aerosol emission across musical instruments can be partly explained by the loudness of performance. Measuring aerosol generation from single notes or simple songs may be sufficient to characterise the aerosol emission range during actual performance, provided a range of loudnesses are accessed. These results provide insight into the factors contributing to aerosol emission during musical performance and facilitate risk assessments associated with infectious respiratory disease transmission in the performing arts.

Influence of talking behavior of infected patients and the associated exposure risk in a ventilated negative-pressure ward

Negative-pressure isolation ward is a primary choice in preventing the spread of outbreaks and safeguarding patient recovery. Inside the ward, patients with respiratory diseases generate virus-carrying bioaerosols through breathing and talking, posing a very high risk of infection to healthcare workers. In this paper, we used numerical simulation to compare the effects of different respiratory behaviors, such as normal breathing, prolonged talking, short talking, and alternating talking, on the spatial and temporal distribution of aerosols in a ward, and to study the risk of infection for healthcare workers. It was found that a short period of time in which a patient talked in a ward increased aerosol concentrations by four orders of magnitude compared to normal breathing. In the ward with the ventilation of up-supply, or the one with side-supply, the impacts of aerosol generation from talking accounted for 62.4% and 42.6% of the total time, respectively. The overall infection risk in wards designed with side-supply ventilation was lower. Patient talking time changes did not affect high-risk areas. However, when healthcare worker and patient talked alternately, the aerosol impact time was slightly extended. In addition, the aerosols produced by talking were mainly deposited on the beds and floors, leading to higher exposure risk for healthcare workers during direct contact with beds. It is hoped that the results of this study can be used as the data basis for the study of aerosol pollution control strategies in medical scenarios, and provide useful suggestions for reducing the risk of infection.

Radiative forcing from aerosol–cloud interactions enhanced by large-scale circulation adjustments

The impact of anthropogenic aerosols on clouds is a leading source of uncertainty in estimating the effect of human activity on the climate system. The challenge lies in the scale difference between clouds (~1–10 km) and general circulation and climate (>1,000 km). To address this, we use convection-permitting simulations conducted in a long and narrow domain, to resolve convection while also including a representation of large-scale processes. We examine a set of simulations that include a sea surface temperature gradient—which drives large-scale circulation—and compare these with simulations that include no gradient. We show that the effective radiative forcing due to aerosol–cloud interactions is strongly enhanced by adjustments of large-scale circulation to aerosol. We find that an increase in aerosol concentration suppresses precipitation in shallow-convective regions, which enhances water vapour transport to the portion of the domain dominated by deep convection. The subsequent increase in latent heat release in deep-convective regions strengthens the overturning circulation and surface evaporation. These changes can explain the increase in cloudiness under higher aerosol concentrations and, consequently, the large aerosol radiative effect. This work highlights the fundamental importance of large-scale circulation adjustments in understanding the effective radiative forcing from aerosol–cloud interactions.

Comparing Aerosol Generation in Human and Animal Tissues During Common Otolaryngology Procedures.

To determine whether hamster and human tissues generate similar amounts of aerosolized particles using common otolaryngology surgical techniques. Quantitative experimental research. University research laboratory. Drilling, electrocautery, and coblation were performed on human and hamster tissues. Particle size and concentration were measured during the surgical procedures using a scanning mobility particle sizer and an aerosol particle sizer (SMPS-APS) and GRIMM aerosol particle spectrometer. SMPS-APS and GRIMM measurements detected at least 2-fold increases in aerosol concentrations compared to baseline during all procedures. Procedures performed on human and hamster tissues produced similar trends and order of magnitude of aerosol concentrations. Generally, hamster tissues produced higher aerosol concentrations compared to human tissues, and some of these differences were statistically significant. Mean particle sizes for all procedures were small (<200 nm), although statistically significant differences in particle size were identified between human and hamster tissues during coblation and drilling. Aerosol-generating procedures performed on human and hamster tissue produce similar trends in aerosol particle concentrations and sizes, although we observed some differences between the 2 tissue types. Further studies should be performed to understand the clinical significance of these differences.

Model-based insights into aerosol perturbation on pristine continental convective precipitation

Abstract. The Tibetan Plateau (TP) is of great importance for weather and climate due to its role as a heat and water resource. Relatively clean aerosol conditions over the Plateau make the study on the aerosol–cloud–precipitation interactions in this pristine continental region distinctive. In order to investigate the impacts of aerosols on small-scale convection processes over the TP, a convective event with precipitation observed on 24 July 2014 in Naqu was selected to explore the influence of aerosols on the onset and intensity of precipitation. We use the Modern-Era Retrospective analysis for Research and Applications Version 2 (MERRA-2) reanalysis to derive the cloud condensation nuclei (CCN) number concentration, which can be regarded as the real-time background. These values are adopted to initialize the regional Weather Research Forecast (WRF) 4.0 meteorological model and to simulate the onset of convective events and the formation of precipitation. Four sets of experiments, named clean (1/10 CCN), control (default setting), Tibetan Plateau (CCN calculated from MERRA-2 reanalysis), and polluted (10 times CCN), were adopted for our simulations. A detailed analysis of the microphysical processes shows that the conversion of cloud water into rain is enhanced by small increases in aerosol concentration, while it is suppressed by larger increases in concentration. However, the transformation of cloud water to graupel and the development of convective clouds are favored under a polluted situation. As a result, the onset of the precipitation is delayed and cold-rain intensity increases.

Correct(ed) Klett-Fernald algorithm for elastic aerosol backscatter retrievals: a sensitivity analysis.

Retrieval algorithms for aerosol elastic backscatter lidars are most commonly based on a signal inversion known as the Klett solution. While often used, a sign error in the original publication has barely been mentioned or recognized in the scientific community. In this study, we present a corrected Klett inversion and a sensitivity analysis of its implementation under different atmospheric conditions. We show that the error's dimension depends on multiple factors, thus preventing trivial a posteriori corrections on the results calculated with the original, uncorrected Klett solution. Comparing the uncorrected with the corrected Klett solution, long integration pathways in combination with low aerosol concentrations lead to substantial relative deviations of more than 100%, whereas short integration pathways with high aerosol concentrations considerably reduce the relative deviations to magnitudes around 15%. The higher the altitude of layers with increased aerosol concentrations, the higher the deviations due to the incorrect usage of Klett's inversion, however on a slight level (≈1%).

An improved representation of aerosol mixing state for air quality–weather interactions

Abstract. We implement a detailed representation of aerosol mixing state in the Global Environmental Multiscale – Modelling Air quality and CHemistry (GEM-MACH) air quality and weather forecast model. Our mixing-state representation includes three categories: one for more hygroscopic aerosol, one for less hygroscopic aerosol with a high black carbon (BC) mass fraction, and one for less hygroscopic aerosol with a low BC mass fraction. The more detailed representation allows us to better resolve two different aspects of aerosol mixing state: differences in hygroscopicity due to aerosol composition and the amount of absorption enhancement of BC due to non-absorbing coatings. Notably, this three-category representation allows us to account for BC thickly coated with primary organic matter, which enhances the absorption of the BC but has a low hygroscopicity. We compare the results of the three-category representation (1L2B, (one hydrophilic, two hydrophobic)) with a simulation that uses two categories, split by hygroscopicity (HYGRO), and a simulation using the original size-resolved internally mixed assumption (SRIM). We perform a case study that is focused on North America during July 2016, when there were intense wildfires over northwestern North America. We find that the more detailed representation of the aerosol hygroscopicity in both 1L2B and HYGRO decreases wet deposition, which increases aerosol concentrations, particularly of less hygroscopic species. The concentration of PM2.5 increases by 23 % on average. We show that these increased aerosol concentrations increase cloud droplet number concentrations and cloud reflectivity in the model, decreasing surface temperatures. Using two categories based on hygroscopicity yields only a modest benefit in resolving the coating thickness on black carbon, however. The 1L2B representation resolves BC with thinner coatings than the HYGRO simulation, resulting in absorption aerosol optical depths that are 3 % less on average, with greater differences over strong anthropogenic source regions. We did not find strong subsequent effects of this decreased absorption on meteorology.

Invisible ship tracks show large cloud sensitivity to aerosol

Cloud reflectivity is sensitive to atmospheric aerosol concentrations because aerosols provide the condensation nuclei on which water condenses1. Increased aerosol concentrations due to human activity affect droplet number concentration, liquid water and cloud fraction2, but these changes are subject to large uncertainties3. Ship tracks, long lines of polluted clouds that are visible in satellite images, are one of the main tools for quantifying aerosol–cloud interactions4. However, only a small fraction of the clouds polluted by shipping show ship tracks5,6. Here we show that even when no ship tracks are visible in satellite images, aerosol emissions change cloud properties substantially. We develop a new method to quantify the effect of shipping on all clouds, showing a cloud droplet number increase and a more positive liquid water response when there are no visible tracks. We directly detect shipping-induced cloud property changes in the trade cumulus regions of the Atlantic, which are known to display almost no visible tracks. Our results indicate that previous studies of ship tracks were suffering from selection biases by focusing only on visible tracks from satellite imagery. The strong liquid water path response we find translates to a larger aerosol cooling effect on the climate, potentially masking a higher climate sensitivity than observed temperature trends would otherwise suggest.

Virtual impaction in compressible flows with pressure recovery

Virtual impactors have been utilized towards classifying and increasing aerosol concentrations in sampling and measurement systems for half a century; in an ideal virtual impactor, sampled particles larger than a critical diameter (known as the cutsize) are directed inertially into a small fraction of the sample flow, known as the minor flow. Concentrating submicrometer particles with virtual impactors while maintaining near-atmospheric pressure downstream in the minor flow remains a challenge, due the low mass-to-drag ratios of these particles. Increased inertial behavior for small mass-to-drag ratio particles can be overcome by increasing flow velocities; however, in most prior work with virtual impaction of submicrometer particles, pressure recovery (keeping the aerosol outlet pressure similar to the inlet pressure) in the receiving tube at high sample flow rates was not investigated. Here, we describe the development and testing of virtual impactors functioning with flow velocities near the sonic limit, capable of submicrometer particle concentration, and with near-complete pressure recovery in the minor flow. We specifically designed, built, and tested two round-nozzle virtual impactors (denoted as VI-1 and VI-2) and evaluated their performances using fluorescent polystyrene latex particles and uranine-doped oleic acid particles with varying particle diameter. The results show that both virtual impactors, operating with 12 L per minute sample flow and a 10:1 sample flow-to-minor flow ratio, have submicrometer cutsizes (∼700 nm and 200 nm for VI-1 and VI-2, respectively) and near-complete pressure recovery. However, significant particle losses were observed in VI-2 with larger particle diameters. To understand such losses and particle trajectories in compressible flow virtual impactors, we also carried out computational fluid dynamics (CFD) simulations coupled with particle trajectory simulations. Importantly, trajectory calculations incorporated a recently developed drag model capable of predicting particle drag coefficients in a wide Mach number and Knudsen number (and hence Reynolds number) range. Trajectory calculations yielded cutsizes and large particle penetration curves in good agreement with experiments, indicating that large particle losses are due to overfocusing (radial inertial motion leading to deposition) within the nozzle and major flow chamber. Overfocusing always leads to an upper size limit in any virtual impactor system, but it is of greater concern in higher velocity systems. In addition to comparing simulations to measurements sampling at atmospheric pressure, we used trajectory calculations to examine compressible flow virtual impactor performance with variable sampling flow pressure and varying the driving pressure in the major flow. Such simulations reveal that sub-atmospheric pressure sampling leads to a reduced penetration “window” for virtual impaction, such that although it is possible for virtual impactor operation in reduced pressure environments, virtual impactors are applicable to a decreasing range of sizes at low pressure.

Study on Spatial and Temporal Characteristics of Surface Albedo at the Northern Edge of the Badain Jaran Desert Based on C + STNLFFM Model.

Obtaining surface albedo data with high spatial and temporal resolution is essential for measuring the factors, effects, and change mechanisms of regional land-atmosphere interactions in deserts. In order to obtain surface albedo data with higher accuracy and better applicability in deserts, we used MODIS and OLI as data sources, and calculated the daily surface albedo data, with a spatial resolution of 30 m, of Guaizi Lake at the northern edge of the Badain Jaran Desert in 2016, using the Spatial and Temporal Non-Local Filter-based Fusion Model (STNLFFM) and topographical correction model (C model). We then compared the results of STNLFFM and C + STNLFFM for fusion accuracy, and for spatial and temporal distribution differences in surface albedo over different underlying surfaces. The results indicated that, compared with STNLFFM surface albedo and MODIS surface albedo, the relative error of C + STNLFFM surface albedo decreased by 2.34% and 3.57%, respectively. C + STNLFFM can improve poor applicability of MODIS in winter, and better responds to the changes in the measured value over a short time range. After the correction of the C model, the spatial difference in surface albedo over different underlying surfaces was enhanced, and the spatial differences in surface albedo between shifting dunes and semi-shifting dunes, fixed dunes and saline-alkali land, and the Gobi and saline-alkali land were significant. C + STNLFFM maintained the spatial and temporal distribution characteristics of STNLFFM surface albedo, but the increase in regional aerosol concentration and thickness caused by frequent dust storms weakened the spatial difference in surface albedo over different underlying surfaces in March, which led to the overcorrection of the C model.

Long-Term Variability of Aerosol Concentrations and Optical Properties over the Indo-Gangetic Plain in South Asia

Emissions of atmospheric pollutants are rapidly increasing over South Asia. A greater understanding of seasonal variability in aerosol concentrations over South Asia is a scientific challenge and has consequences due to a lack of monitoring and modelling of air pollutants. Therefore, this study investigates aerosol patterns and trends over some major cities in the Indo-Gangetic Plain of the South Asia, i.e., Islamabad, Lahore, Delhi, and Dhaka, by using simulations from the Modern -Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2) model and satellite measurements (Moderate Resolution Imaging Spectroradiometer, (MODIS)) from 2000 to 2020. The results show that seasonal MODIS–aerosol optical depth (AOD) during 2000−2020 in Lahore is 0.5, 0.52, 0.92, and 0.71, while in Islamabad 0.25, 0.32, 0.45, and 0.38, in Delhi 0.68, 0.6, 1.0, and 0.77, and in Dhaka 0.79, 0.75, 0.78 and 0.55 values are observed during different seasons, i.e., winter, spring, summer, and autumn, respectively. The analysis reveals a significant increase in aerosol concentrations by 25%, 24%, 19%, and 14%, and maximum AOD increased by 15%, 14%, 19%, and 22% during the winter of the last decade (2011–2020) over Islamabad, Lahore, Delhi, and Dhaka, respectively. In contrast, AOD values decreased during spring by −5%, −12%, and −5 over Islamabad, Lahore, and Delhi, respectively. In Dhaka, AOD shows an increasing trend for all seasons. Thus, this study provides the aerosol spatial and temporal variations over the South Asian region and would help policymakers to strategize suitable mitigation measurements.

Increased aerosol concentrations in the High Arctic attributable to changing atmospheric transport patterns

The Arctic environment has changed profoundly in recent decades. Aerosol particles are involved in numerous feedback mechanisms in the Arctic, e.g., aerosol-cloud/radiation interactions, which have important climatic implications. To understand changes in different Arctic aerosol types and number concentrations, we have performed a trend analysis of particle number size distributions, their properties, and their associated air mass history at Villum Research Station, northeastern Greenland, from 2010 to 2018. We found that, during spring, the total/ultrafine mode number concentration and the time air masses spent over the open ocean is significantly increasing, which can be ascribed to transport patterns changing to more frequent arrival from the ice-free Greenland Sea. We found that, during summer, the total/ultrafine mode number concentration, the occurrence of the Nucleation cluster (i.e. newly formed particles from gas to particle conversion), and the time air masses spent over the open ocean is significantly increasing. This can also be attributed to changing transport patterns, here with air masses arriving more frequently from Baffin Bay. Finally, we found that, during autumn, the ultrafine number concentration and the occurrence of the Pristine cluster (i.e. clean, natural Arctic background conditions) is significantly increasing, which is likely due to increasing amounts of accumulated precipitation along the trajectory path and decreasing time air masses spent above the mixed layer, respectively. Our results demonstrate that changing circulation and precipitation patterns are the factors predominantly affecting the trends in aerosol particle number concentrations and the occurrence of different aerosol types in northeastern Greenland.

Two Distinct Modes of Climate Responses to the Anthropogenic Aerosol Forcing Changes

Abstract Unlike greenhouse gases (GHGs), anthropogenic aerosol (AA) concentrations have increased and then decreased over the past century or so, with the timing of the peak concentration varying in different regions. To date, it has been challenging to separate the climate impact of AAs from that due to GHGs and background internal variability. We use a pattern recognition method, taking advantage of spatiotemporal covariance information, to isolate the forced patterns for the surface ocean and associated atmospheric variables from the all-but-one forcing Community Earth System Model ensembles. We find that the aerosol-forced responses are dominated by two leading modes, with one associated with the historical increase and future decrease of global mean aerosol concentrations (dominated by the Northern Hemisphere sources) and the other due to the transition of the primary sources of AA from the west to the east and also from Northern Hemisphere extratropical regions to tropical regions. In particular, the aerosol transition effect, to some extent compensating the global mean effect, exhibits a zonal asymmetry in the surface temperature and salinity responses. We also show that this transition effect dominates the total AA effect during recent decades, e.g., 1967–2007.

Spatio-Temporal Monitoring of Atmospheric Pollutants Using Earth Observation Sentinel 5P TROPOMI Data: Impact of Stubble Burning a Case Study

The problems of atmospheric pollutants are causing significant concern across the globe and in India. The aggravated level of atmospheric pollutants in the surrounding environment poses serious threats to normal living conditions by deteriorating air quality and causing adverse health impacts. Pollutant concentration increases during harvesting seasons of Kharif/Rabi due to stubble burning and is aggravated by other points or mobile sources. The present study is intended to monitor the spatio-temporal variation of the major atmospheric pollutants using Sentinel-5P TROPOMI data through cloud computing. Land Use/Land Cover (LULC-categorization or classification of human activities and natural coverage on the landscape) was utilised to extract the agricultural area in the study site. It involves the cloud computing of MOD64A1 (MODIS Burned monthly gridded data) and Sentinel-5P TROPOMI (S5P Tropomi) data for major atmospheric pollutants, such as CH4, NO2, SOX, CO, aerosol, and HCHO. The burned area output provided information regarding the stubble burning period, which has seen post-harvesting agricultural residue burning after Kharif crop harvesting (i.e., rice from April to June) and Rabi crop harvesting (i.e., wheat from September to November). The long duration of stubble burning is due to variation in farmers’ harvesting and burning stubble/biomass remains in the field for successive crops. This period was used as criteria for considering the cloud computing of the Sentinel-5P TROPOMI data for atmospheric pollutants concentration in the study site. The results showed a significant increase in CH4, SO2, SOX, CO, and aerosol concentration during the AMJ months (stubble burning of Rabi crops) and OND months (stubble burning of Kharif crops) of each year. The results are validated with the ground control station data for PM2.5/PM10. and patterns of precipitation and temperature-gridded datasets. The trajectory frequency for air mass movement using the HYSPLIT model showed that the highest frequency and concentration were observed during OND months, followed by the AMJ months of each year (2018, 2019, 2020, and 2021). This study supports the role and robustness of Earth observation Sentinel-5P TROPOMI to monitor and evaluate air quality and pollutants distribution.

The Aerosol-Generating Effect Among Noninvasive Positive Pressure Ventilation, High-Flow Nasal Cannula, Nonrebreather Mask, Nasal Cannula, and Ventilator-Assisted Preoxygenation

To evaluate aerosol dispersion and exposure risk during oxygenation therapy among health care personnel. This study compared the aerosol dispersion effect produced through continuous positive airway pressure (CPAP), bilevel positive airway pressure (BiPAP), BiPAP with face coverings, a high-flow nasal cannula (HFNC) with face coverings, nasal cannula oxygenation (NCO) at 15 L/min with face coverings, nonrebreather mask (NRM), and ventilator-assisted preoxygenation (VAPOX) during oxygenation therapy at a minute ventilation of 10 L/min and 20 L/min. The length and width of aerosol dispersion were recorded, and aerosol concentrations were then detected at a mannequin's head, trunk, and feet. The average length dispersion distance of CPAP was 47.12 cm (SD, 12.56 cm), of BiPAP was 100.13 cm (SD, 6.03 cm), of BiPAP with face coverings was 62.20 cm (SD, 8.46 cm), of HFNC with face coverings was 67.09 cm (SD, 12.74 cm); of NCO with face coverings was 85.55 cm (SD, 7.28 cm); and of NRM was 63.08 cm (SD, 15.33 cm); VAPOX showed no visible dispersion. The aerosol concentrations at the feet under CPAP and at the head under BiPAP were significantly higher than those observed without an oxygen device. Compared with no oxygen device, the aerosol concentration with HFNC was higher at the mannequin's head, trunk, and feet; whereas it was lower with VAPOX and NRM. Moreover, when translated to the number of virus particles required to infect medical personnel (Nf), VAPOX took more time to achieve Nf than other devices. Strong flow from the oxygenation devices resulted in increased aerosol concentrations. CPAP at the feet side, BiPAP at the head side, HFNC, and NCO with face coverings significantly increase aerosol exposure and should be used with caution. Aerosol concentrations at all positions were lower with NRM and VAPOX.