Search

Bromine atom (Br) reactions lead to ozone depletion in the troposphere and stratosphere. Photodegradation of bromocarbons is one of the main sources of bromine atoms in the atmosphere. Here, we use high-level ab initio methods, including spin–orbit effects, to study the photodissociation of the CH2Br radical. All possible fragmentation pathways, namely CH2Br + hν → CH2 + Br, HCBr + H, and CBr + H2, have been analyzed. Potential-energy curves of the ground and several excited electronic states along the corresponding dissociating bond distance of each pathway have been calculated. Considering the actinic fluxes of solar irradiation in the troposphere and in the stratosphere in the relevant range of frequencies, it is found that the first five excited states of CH2Br can be accessed from the ground state. Analysis of the potential curves shows that the pathways producing CH2 + Br and HCBr + H can proceed through a fast direct dissociation mechanism, while the pathway leading to CBr + H2 involves much slower dissociation mechanisms like internal conversion between electronic states, predissociation, or tunneling through exit barriers. The main implications are that the two faster channels are predicted to be dominant, and the slower pathway is expected to be less relevant. The tropospheric and stratospheric solar actinic fluxes also allow for further dissociation of the HCBr and CBr fragments, generating additional Br atoms, provided that they survive possible collisions with other atmospheric reagents. Finally, we discuss the possible effect of each of the three CH2Br dissociation pathways on the depletion of atmospheric ozone. [ABSTRACT FROM AUTHOR]

Atmospheric hydrogen concentrations have been increasing in recent decades. Hydrogen is radiatively inert, but it is chemically reactive and exerts an indirect radiative forcing through chemistry that perturbs the concentrations of key species within the troposphere, including ozone. Using the atmospheric version of the United Kingdom Earth System Model, we analyse the impact of 10% increased surface concentrations of hydrogen on ozone production and loss. We also analyse the impact of this hydrogen in atmospheres with lower anthropogenic emissions of nitrogen oxides (80% and 30% of present-day anthropogenic surface emissions), as this is a likely outcome of the transition from fossil fuels towards cleaner technologies. In each case, we also assess the changes in hydroxyl radical concentration and hence methane lifetime and calculate the net impact on the hydrogen tropospheric global warming potential (GWP). We find that the hydrogen tropospheric GWP100 will change relatively little with decreases in surface anthropogenic NOx emissions (9.4 and 9.1 for our present day and 30% anthropogenic emissions, respectively). The current estimate for hydrogen GWP100 can therefore be applied to future scenarios of differing NOx, although this conclusion may be impacted by future changes in emissions of other reactive species. [ABSTRACT FROM AUTHOR]

In recent years, the concentrations of ozone and the pollution days with ozone as the primary pollutant have been increasing year by year. The sources of regional ozone mainly depend on local photochemical formation and transboundary transport. The latter is influenced by different weather circulations. How to effectively reduce the inter-regional emission to control ozone pollution under different atmospheric circulation is rarely reported. In this study, we classify the atmospheric circulation of ozone pollution days from 2014 to 2019 over Central China based on the Lamb–Jenkinson method and the global analysis data of the fifth-generation European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis (ERA5) operation. The effectiveness of emission control to alleviate ozone pollution under different atmospheric circulation is simulated by the WRF-Chem model. Among the 26 types of circulation patterns, 9 types of pollution days account for 79.5% of the total pollution days and further classified into 5 types. The local types (A and C type) are characterized by low surface wind speed and stable weather conditions over Central China due to a high-pressure system or a southwest vortex low-pressure system, blocking the diffusion of pollutants. Sensitivity simulations of A-type show that this heavy pollution process is mainly contributed by local emission sources. Removing the anthropogenic emission of pollutants over Central China would reduce the ozone concentration by 39.1%. The other three circulation patterns show pollution of transport characteristics affected by easterly, northerly, or southerly winds (N-EC, EC, S-EC-type). Under the EC-type, removing anthropogenic pollutants of East China would reduce the ozone concentration by 22.7% in Central China. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Remote Sensing is the property of Editorial Office of Journal of Remote Sensing & Science Publishing Co. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Volatile organic compounds (VOCs) have been extensively studied because of their significant roles as precursors of atmospheric ozone and secondary organic aerosol pollution. The research aims to comprehend the current advancements in domestic and international VOC emission accounting. The study utilized the CiteSpace software to represent the pertinent material from Web of Science visually. The hot spots and future development trends of VOC emission calculation are analyzed from the perspectives of thesis subject words, cooperative relationships, co-citation relationships, journals, and core papers. According to the statistics, the approaches most often employed in VOC accounting between 2013 and 2023 are source analysis and emission factor method. Atmospheric environment is the journal with the most publications in the area. The Chinese Academy of Sciences and the University of Colorado System are prominent institutions in VOC emission accounting research, both domestically and internationally. The primary research focuses on the realm of VOC emission accounting clusters, which are "emission factor," "source analysis," "model," "air quality," and "health." A current trend in VOC emission accounting involves the construction of a VOC emission inventory using a novel model that combines emission factors and source analysis. This study reviews the progress made in calculating volatile organic compound (VOC) emissions over the past decade. It aims to provide researchers with a new perspective to promote the development of this field. [ABSTRACT FROM AUTHOR]

The dominant fraction of anthropogenic volatile organic compound (VOC) emissions shifted from transportation fuels to volatile chemical products (VCP) in Los Angeles (LA) in 2010. This shift in VOC composition raises the question about the importance of VCP emissions for ozone (O3) formation. In this study, O3 chemistry during the CalNex 2010 was modeled using the Master Chemical Mechanism (MCM) version 3.3.1 and a detailed representation of VCP emissions based on measurements combined with inventory estimates. The model calculations indicate that VCP emissions contributed to 23% of the mean daily maximum 8‐hr average O3 (DMA8 O3) during the O3 episodes. The simulated OH reactivity, including the contribution from VCP emissions, aligns with observations. Additionally, this framework was employed using four lumped mechanisms with simplified representations of emissions and chemistry. RACM2‐VCP showed the closest agreement with MCM, with a slight 4% increase in average DMA8 O3 (65 ± 13 ppb), whereas RACM2 (58 ± 13 ppb) and SAPRC07B (59 ± 14 ppb) exhibited slightly lower levels. CB6r2, however, recorded reduced concentrations (37 ± 10 ppb). Although emissions of O3 precursors have declined in LA since 2010, O3 levels have not decreased significantly. Model results ascribed this trend to the rapid reduction in NOX emissions. Moreover, given the impact of COVID‐19, an analysis of 2020 reveals a shift to a NOX‐limited O3 formation regime in LA, thereby diminishing the influence of VCPs. This study provides new insights into the impact of VCP emissions on O3 pollution from an in‐depth photochemical perspective. Plain Language Summary: In the 2010 CalNex study, researchers found that volatile organic compounds (VOCs) were predominantly emitted from volatile chemical products (VCPs) like solvents. In our subsequent research, using a detailed chemical model, we discovered that about a quarter of the mean daily maximum 8‐hr average ozone was contributed by these everyday products during ozone episodes. This insight is critical as it underscores how these emissions significantly speed up ozone formation through accelerated chemical reactions. We also evaluated various simplified chemical mechanisms for ozone prediction, finding that the one incorporating key reactions of VOC species was most accurate. Further, our analysis suggests that the slight increase in Los Angeles' ozone levels since 2010 can likely be attributed to faster reductions in NOX emissions relative to VOCs. Notably, the reduction in NOX emissions by 2020 considerably diminished the impact of VCPs on ozone levels. However, given the uncertain future of NOX emissions and the ongoing rise in emissions from everyday products, it remains essential to control these emissions. Key Points: Volatile chemical product emissions accounted for 23% of mean daily max 8‐hr ozone in ozone episodes, as per the 2010 CalNex studyVCP emissions boost ozone formation by increasing primary production and efficient recycling of ROx radicals, thus enhancing pollution2020s reduction in NOx emissions in Los Angeles, potentially due to COVID‐19, led to a NOx‐limited state, lessening VCPs' impact on ozone [ABSTRACT FROM AUTHOR]

Due to the complex and variable nature of the atmospheric conditions, traditional multi-wavelength differential absorption lidar (DIAL) methods often suffer from significant errors when inverting ozone concentrations. As the detection range increases, there is a higher demand for Signal to Noise Ratio (SNR) in lidar signals. Based on this, the paper discusses the impact of different atmospheric factors on the accuracy of ozone concentration inversion. It also compares the advantages and disadvantages of the two-wavelength differential method and the three-wavelength dual-differential method under both noisy and noise-free conditions. Firstly, the errors caused by air molecular extinction, aerosol extinction, and backscatter terms in the inversion using the two-wavelength differential method were simulated. Secondly, the corrected inversion errors were obtained through direct correction and the introduction of a three-wavelength dual differential correction. Finally, addressing the issue of insufficient SNR in practical inversions, the inversion errors of the two correction methods were simulated by constructing lidar parameters and incorporating appropriate noise. The results indicate that the traditional two-wavelength differential algorithm is significantly affected by aerosols, making it more sensitive to aerosol concentration and structural changes. On the other hand, the three-wavelength dual differential algorithm requires a higher SNR in lidar signals. Therefore, we propose a novel strategy for inverting atmospheric ozone concentration, which prioritizes the use of the three-wavelength dual-differential method in regions with high SNR and high aerosol concentration. Conversely, the direct correction method utilizing the two-wavelength differential approach is used. This approach holds the potential for high-precision ozone concentration profile inversion under different atmospheric conditions. [ABSTRACT FROM AUTHOR]

The article discusses Peter Balakian's poem "Ozone Journal," which explores various topics such as the Armenian genocide, climate change, and personal experiences. The poem uses fragmentation as a technique to address limit events and create an affective experience for readers. It aims to communicate the deep entanglement between humans and the environment and highlights the potential of poetry to evoke emotions and understanding. The poem's focus on trauma and everyday life, as well as its use of land affect, demonstrates the effectiveness of affective storytelling in addressing issues like trauma and the climate crisis. [Extracted from the article]

Ozone is a pollutant formed in the atmosphere by photochemical processes involving nitrogen oxides (NO x) and volatile organic compounds (VOCs) when exposed to sunlight. Tropospheric boundary layer ozone is regularly measured at ground stations and sampled infrequently through balloon, lidar, and crewed aircraft platforms, which have demonstrated characteristic patterns with altitude. Here, to better resolve vertical profiles of ozone within the atmospheric boundary layer, we developed and evaluated an uncrewed aircraft system (UAS) platform for measuring ozone and meteorological parameters of temperature, pressure, and humidity. To evaluate this approach, a UAS was flown with a portable ozone monitor and a meteorological temperature and humidity sensor to compare to tall tower measurements in northern Wisconsin. In June 2020, as a part of the WiscoDISCO20 campaign, a DJI M600 hexacopter UAS was flown with the same sensors to measure Lake Michigan shoreline ozone concentrations. This latter UAS experiment revealed a low-altitude structure in ozone concentrations in a shoreline environment showing the highest ozone at altitudes from 20–100 m a.g.l. These first such measurements of low-altitude ozone via a UAS in the Great Lakes region revealed a very shallow layer of ozone-rich air lying above the surface. [ABSTRACT FROM AUTHOR]

Cooking organic aerosol (COA) is one of the major constituents of particulate matter in urban areas. COA is oxidized by atmospheric oxidants such as ozone, changing its physical, chemical and toxicological properties. However, atmospheric chemical lifetimes of COA and its tracers such as oleic acid are typically longer than those that have been estimated by laboratory studies. We tackled the issue by considering temperature. Namely, we hypothesize that increased viscosity of COA at ambient temperature accounts for its prolonged atmospheric chemical lifetimes in wintertime. Laboratory-generated COA particles from cooking oil were exposed to ozone in an aerosol flow tube reactor for the temperature range of - 20 to 35 °C. The pseudo-second-order chemical reaction rate constants (k2) were estimated from the experimental data by assuming a constant ozone concentration in the flow tube. The estimated values of k2 decreased by orders of magnitude for lower temperatures. The temperature dependence in k2 was fit well by considering the diffusion-limited chemical reaction mechanism. The result suggested that increased viscosity was likely the key factor to account for the decrease in chemical reactivity at the reduced temperature range, though the idea will still need to be verified by temperature-dependent viscosity data in the future. In combination with the observed global surface temperature, the atmospheric chemical lifetimes of COA were estimated to be much longer in wintertime (> 1 h) than in summertime (a few minutes) for temperate and boreal regions. Our present study demonstrates that the oxidation lifetimes of COA particles will need to be parameterized as a function of temperature in the future for estimating environmental impacts and fates of this category of particulate matter. [ABSTRACT FROM AUTHOR]

As the main precursors of fine particles and ozone, volatile organic compounds (VOCs) are the crucial factor on atmospheric environment. Due to the low energy consumption, noble metal-loaded catalysts have been widely used in catalytic oxidation of VOCs, traditional nano-catalysts suffer from low atom utilization, poor product selectivity, and high cost, but single-atom catalysts give a great potential in this process. This paper describes the synthesis strategies and structural characteristics of metal-loaded single-atom catalysts in the last decades. The interaction of metal/support and its resulted activities on catalytic oxidation of VOCs is stressed. Meanwhile, the interaction of metal/support is further analyzed based on the model construction and theoretical calculation. Finally, the mechanisms of VOCs combustion on noble metal single-atom catalysts are concluded, and future development direction is proposed. [ABSTRACT FROM AUTHOR]

The article is a message from the president of the Limnology & Oceanography Bulletin, discussing the upcoming turnover in board membership and asking for feedback how the organization can better support them. The president expresses gratitude to outgoing board members and welcomes new members. They highlight the importance of collaboration and scientific knowledge in addressing environmental challenges and mention the recent successful Aquatic Sciences Meeting in Madison, Wisconsin. The president also discusses the changes the organization has undergone in the past decade, including switching publishers, navigating the pandemic, and changing the association management company. They emphasize the importance of member input and involvement in shaping the organization's future. [Extracted from the article]

The machine learning model used to predict ozone concentrations at the Listvyanka monitoring station in the Baikal region is described. The model was trained and verified using automatic ground-based gas analyzer ozone measurements. Random forest and boosting machine learning models were used. According to the ERA5 reanalysis, the mean absolute error of ozone values exceeds 16 ppb, and the mean percentage error is 80%. The respective errors in the ozone values calculated using machine learning models are 6.7 ppb and 29%. The results of forecasting are the most sensitive to the season, air temperature, and vegetation. The ozone values for 2017–2022 were simulated and analyzed using the trained model and reanalysis data. [ABSTRACT FROM AUTHOR]

This research aims to comprehensively examine the clearness index (KT), total ozone column (TOC), and ultraviolet A (UVA) and ultraviolet B radiation (UVB) over Lumbini, Nepal (27°28' N, 83°16' E, and 150 m above sea level) throughout the 11 years of solar cycle 24 (2008 to 2018). The Lumbini, a highly polluted region, is important in advancing the identification and analysis of TOC variations across regions with similar geographical and climatic attributes. Data from the Ozone Monitoring Instrument (OMI) of the EOS-AURA satellite of NASA were used to analyze the daily, monthly, seasonal, and annual trends in the clearness index (KT), ultraviolet A (UVA), ultraviolet B (UVB), and TOC from the Comprehensive Environmental Data Archive (CEDA). The study found that the yearly averages for KT, TOC, UVA, and UVB were 0.55 ± 0.13, 272 ± 14 DU, 12.61 ± 3.50 W/m2, and 0.32 ± 0.11 W/m2, respectively. These values provide insights into the long-term variations in atmospheric parameters at Lumbini. The study also applied the continuous wavelet transform (CWT) to analyze KT, TOC, UVA, and UVB temporal variations. The power density peak of 35,000 DU2 in the TOC was observed from the end of 2010 to the end of 2011, within 8.5 years, underscoring the significance of analyzing TOC dynamics over extended durations to understand atmospheric behavior comprehensively. [ABSTRACT FROM AUTHOR]

Atmospheric aerosol hygroscopicity and reactivity play key roles in determining the aerosol's fate and are strongly affected by its composition and physical properties. Fatty acids are surfactants commonly found in organic aerosol emissions. They form a wide range of different nanostructures dependent on water content and mixture composition. In this study we follow nano-structural changes in mixtures frequently found in urban organic aerosol emissions, i.e. oleic acid, sodium oleate and fructose, during humidity change and exposure to the atmospheric oxidant ozone. Addition of fructose altered the nanostructure by inducing molecular arrangements with increased surfactant-water interface curvature. Small-Angle X-ray Scattering (SAXS) was employed for the first time to derive the hygroscopicity of each nanostructure by measuring time- and humidity-resolved changes in nano-structural parameters. We found that hygroscopicity is directly linked to the specific nanostructure and is dependent on the nanostructure geometry. Reaction with ozone revealed a clear nanostructure-reactivity trend, with notable differences between the individual nanostructures investigated. Simultaneous Raman microscopy complementing the SAXS studies revealed the persistence of oleic acid even after extensive oxidation. Our findings demonstrate that self-assembly of fatty acid nanostructures can significantly impact two key atmospheric aerosol processes: water uptake and chemical reactivity, thus directly affecting the atmospheric lifetime of these materials. This could have significant impacts on both urban air quality (e.g. protecting harmful urban emissions from atmospheric degradation and therefore enabling their long-range transport), and climate (e.g. affecting cloud formation), with implications for human health and wellbeing. [ABSTRACT FROM AUTHOR]

In recent decades, the ozone layer has suffered considerable damage, increasing the entry of ultraviolet (UV) light into the atmosphere and reaching the earth’s surface, negatively affecting life. Accordingly, researchers aimed to solve this problem by synthesizing advanced UV-shielding materials. On the other hand, developing an easy and green strategy to prepare functional materials without standing properties based on naturally abundant and environmentally friendly raw materials is highly desirable for sustainable development. Because biomass-derived materials are sustainable and biodegradable, they present a promising substitute for petroleum-based polymers. The three main structural constituents of the plant biomass-based materials that are naturally available are cellulose, hemicellulose, and lignin. This review details current developments using wood-based products such as cellulose, hemicellulose, and lignin in UV-shielding applications. It will start with assembling the structure and chemistry of cellulose, hemicellulose, and lignin, followed by their contributions to preparing UV-shielding materials. Finally, it will briefly discuss the different processing methods for the design of UV-shielding materials. The wood by-products offer additional opportunities to use the whole tree harvest. [ABSTRACT FROM AUTHOR]

The fine particulate matter (PM2.5) in Chinese megacities has declined significantly after the implementation of strict mitigation strategies since 2013. However, the concentration of wintertime nitrate in PM2.5 (p‐NO3‐) has only changed slightly and became the dominant inorganic component despite considerable precursor emission reductions. Discerning chemical mechanisms leading to nitrate growth during haze events is critical to implementing effective pollution mitigation policies. The oxygen isotope anomaly of nitrate (Δ17O(NO3−)) is a powerful means to distinguish nitrate formation mechanisms. Nevertheless, the observed high Δ17O(NO3−) values were significantly underestimated by chemical transport models during extreme haze events (PM2.5 > 225 μg m−3) in Beijing, indicating an incomplete understanding of nitrate chemistry. To reconcile this model‐observation discrepancy, we compiled reported Δ17O(NO3−) data in Beijing haze along with relevant observational parameters (e.g., hydroxyl (OH) reactivity, peroxyl radical concentrations), then tested assumptions on Δ17O of key precursors (e.g., OH and nitrogen dioxide (NO2)), recalculated Δ17O(NO3−) and compared them with observations. Our results indicate that considering heterogeneous dinitrogen pentoxide reactions on chlorine‐containing aerosols (N2O5 + Cl− chemistry) with a nitryl chloride (ClNO2) yield of ∼0.75 can explain the observed high Δ17O(NO3−) during extreme haze events. According to the Δ17O(NO3−) data, on average this heterogeneous N2O5 + Cl− chemistry can explain ∼60% of nighttime nitrate production and make daytime and nocturnal pathways equally important in winter Beijing haze (PM2.5 > 75 μg m−3). Our results highlight the critical role of reactive chlorine chemistry in air pollution/chemistry in inland cities. Plain Language Summary: Δ17O(NO3−) is an independent tool to assess nitrate formation mechanisms. However, the GEOS‐Chem model persistently underestimates the observed Δ17O(NO3−) during extreme haze periods in urban Beijing, implying an unknown or misunderstood NOx chemistry characterized by high Δ17O signatures. Here, we aim to reconcile this discrepancy to advance our understanding of nitrate formation mechanisms in winter haze. To this end, we reassess the isotopic signatures of key precursors relating to NOx chemistry constrained by atmospheric chemistry parameters (e.g., OH reactivity, hydrogen peroxyl (HO2) and organic peroxyl (RO2) radicals, and ozone (O3)). We find that (a) steady‐state OH radical should bear positive Δ17O values but are unable to reconcile the gap between the observed and modeled Δ17O(NO3−); (b) ClNO2 production is efficient under haze conditions in urban Beijing, which is able to explain the gap between the observed and modeled Δ17O(NO3−). The photolysis of ClNO2 has significant effects on atmospheric oxidative capacity and aerosol pollution. Although halogen chemistry prevails in the marine boundary layer, our results highlight the importance of halogen chemistry in nitrate pollution, which should be comprehensively incorporated into air quality models and field observational research to better understand atmospheric chemistry in urban air. Key Points: Heterogeneous N2O5 + Cl− chemistry is important for nitrate production in winter Beijing hazeA ClNO2 yield of 0.75 from heterogeneous N2O5 + Cl− chemistry can explain both the observed high Δ17O(NO3−) and ClNO2 concentrationsDiurnal sampling and subsequent Δ17O(NO3−) interpretation in urban regions need to consider differences in the surface and residual layers [ABSTRACT FROM AUTHOR]

Nitrogen oxides, emitted from air traffic, are of concern due to their impact on climate by changing atmospheric ozone and methane levels. Using the DLR research aircraft Falcon, total reactive nitrogen (NOy) measurements were carried out at high altitudes to characterize emissions in the fresh aircraft exhaust from the latest generation Rolls-Royce Trent XWB-84 engine aboard the long-range Airbus A350-941 aircraft. The impact of different engine thrust settings, monitored in terms of combustor inlet temperature, pressure, and engine fuel flow, was tested for two different fuel types: Jet A-1 and for the first time a 100 % sustainable aviation fuel (SAF) under similar atmospheric conditions. During ground emission measurements, a range of combustor temperatures and an additional blended SAF were tested. We confirm that the NOx emission index increases with increasing combustion temperature, pressure and fuel flow. We find that as expected, the fuel type has no measurable effect on the NOx emission index. These measurements are used to compare to cruise NOx emission index estimates from three engine emission models. Our measurements thus help to understand the ground to cruise correlation of current emission models while serving as input for climate modelling, and extending the extremely sparse data set on in-flight aircraft NOx emissions to newer engine generations. [ABSTRACT FROM AUTHOR]

The impacts on atmospheric ozone (O3) due to wildfires are difficult to characterize due to the many factors that affect O3's formation rate and the episodic nature of fire events. This study uses a very large set of air quality data (518,987 6‐hr data points) collected in Western Canada from 2001 to 2019 to determine the prevalence and severity of fire‐driven increases to measured O3 values. Wildfire events are identified using the automated Trajectory‐Fire Interception Method (TFIM), looking for interceptions between HYSPLIT back‐trajectories and wildfire hotspots. As with other studies, which have used more restricted sets of measurements, the results from this large‐scale, data‐driven approach indicate increases in the O3 mixing ratio with wildfire impact, on average ∼2 ppbv across all wildfire time periods. To understand the factors which lead to the largest increases, and to better compare to other studies looking at individual fire events, wildfire events are classified using their distance from the air quality measurement location, time of measurement, and corresponding PM2.5 value. Increases to O3 are largest during the daytime, when fires occur close to the air quality measurement, and with corresponding measurements of PM2.5 > 25 μg/m3. When an upper‐limit correction for the bias in UV photometric detection of ozone with MnCl2 scrubbers is applied, the analysis still yields a persistent increase in O3 during wildfires except for the highest PM2.5 levels. However, a more accurate correction to the potential bias is needed to fully understand the magnitude of the impact of wildfires on O3. Plain Language Summary: Wildfires emit particulate matter and gaseous molecules into the atmosphere leading to poor air quality downwind of the fire. In particular, wildfires emit precursors which form ozone, a respiratory irritant that is associated with negative health effects. The conditions which favor the formation of ozone without wildfires and in wildfire plumes are complex, and depend on factors such as sunlight, temperature, and other pollutant concentrations. The complexity of the formation of ozone without wildfires, combined with the episodic nature of wildfire events makes it difficult to understand how wildfire events impact local ozone concentrations. This study examines the ozone data from 73 different air quality stations from across Western Canada from 2001 to 2019 to investigate how wildfire events have impacted measured ozone. From this analysis, a small increase in ozone during wildfires is observed, and the largest increases happen during big fire events with high concentrations of particulate matter in the daytime. Increases in ozone were similar at rural locations and urban locations in one case study centered around Edmonton. Key Points: Together, all wildfire events in Western Canada between 2001 and 2019 lead to an average increase of 2 ppbv of O3The extent of the O3 increase is sensitive to measurement time, plume age, and measured PM2.5O3 increases remain during wildfire events after correction of potential O3 measurement bias, except during severe wildfire events [ABSTRACT FROM AUTHOR]

• Summarized the initial ozonolysis rules of typical LCMs in the atmosphere. • Predicted eco-toxicity of CEB-2F and its transformation products. • Revealed the adsorption mechanism of typical LCMs on the surface of TiO 2 clusters. • Elucidated the role of TiO 2 clusters on the ozonolysis of typical LCMs. • Illustrated the long-distance transmission capability of LCMs. Mineral aerosol particles significantly impact environmental risk prediction of liquid crystal monomers (LCMs). In this work, we investigated the reaction mechanisms and kinetics of three typical LCMs (4-cyano-3,5-difluorophenyl 4-ethylbenzoate (CEB-2F), 4-cyano-3-fluorophenyl 4-ethylbenzoate (CEB-F), and 4-cyanophenyl 4-ethylbenzoate (CEB)) with ozone (O 3) in the atmospheric gas, liquid, and particle phases employing density functional theory (DFT). Here, O 3 is prone to add to the benzene ring without F atom(s) in the selected LCMs. The ozonolysis products are aldehydes, carboxylic acids, epoxides, and unsaturated hydrocarbons containing aromatic rings. Those products undergo secondary ozonolysis to generate small molecular compounds such as glyoxal, which is beneficial for generating secondary organic aerosol (SOA). Titanium dioxide (TiO 2), an essential component of mineral aerosol particles, has good adsorption properties for LCMs; however, it slightly reduces the reactivity with O 3. At 298 K, the reaction rate constant of the selected LCMs reacting with O 3 in the gas and atmospheric liquid phases is (2.74‒5.53) × 10−24 cm3/(mol·sec) and 5.58 × 10−3‒39.1 L/(mol·sec), while CEB-2F reacting with O 3 on (TiO 2) 6 cluster is 1.84 × 10−24 cm3/(mol·sec). The existence of TiO 2 clusters increases the persistence and long-distance transportability of LCMs, which enlarges the contaminated area of LCMs. [Display omitted] [ABSTRACT FROM AUTHOR]

The pollution of atmospheric ozone in China shows an obvious upward trend in the past decade. However, the studies on the atmospheric oxidation capacity and O 3 formation in four seasons in the southeastern coastal region of China with the rapid urbanization remain limited. Here, a four-season field observation was carried out in a coastal city of southeast China, using an observation-based model combining with the Master Chemical Mechanism, to explore the atmospheric oxidation capacity (AOC), radical chemistry, O 3 formation pathways and sensitivity. The results showed that the average net O 3 production rate (14.55 ppbv/hr) in summer was the strongest, but the average O 3 concentrations in autumn was higher. The AOC and RO x levels presented an obvious seasonal pattern with the maximum value in summer, while the OH reactivity in winter was the highest with an average value of 22.75 sec−1. The OH reactivity was dominated by oxygenated VOCs (OVOCs) (30.6%-42.8%), CO (23.2%-26.8%), NO 2 (13.6%-22.0%), and alkenes (8.4%-12.5%) in different seasons. HONO photolysis dominated OH primary source on daytime in winter, while in other seasons, HONO photolysis in the morning and ozone photolysis in the afternoon contributed mostly. Sensitivity analysis indicated that O 3 production was controlled by VOCs in spring, autumn and winter, but a VOC-limited and NO x -limited regime in summer, and alkene and aromatic species were the major controlling factors to O 3 formation. Overall, the study characterized the atmospheric oxidation capacity and elucidated the controlling factors for O 3 production in the coastal area with the rapid urbanization in China. [ABSTRACT FROM AUTHOR]

Ozone has a significant impact on the environment. Atmospheric ozone concentration in coastal tourist areas now gains greater importance because tourists' skin is directly exposed to sunlight. The current research provides the best prediction model to improve the prediction accuracy of ozone level for the coastal area of Bangladesh. The functional time series analysis (FTSA) is a direct extension of function-to-function regression model dealing with continuous curves. The proposed functional time series–based model was applied to the hourly ozone series observed over 92 days starting from March 2019 to May 2019 in the coastal area of Bangladesh. Descriptive measures were used to estimate the overall temporal patterns, and the functional principal component regression model (FPCR) was used to predict first day of monsoon season. In addition, functional autoregressive model (FAR(1)) was used to measure the impact of 1-h differences on next day's ozone levels. Results of functional principal component regression reveal complex dynamic patterns of the ozone levels over hours and days. The first principal component primarily models afternoon-hour ozone levels, and the second principal component models the complex difference pattern between midnight to early morning, and the rest of the hourly ozone concentration. In addition, from FAR(1) model, our results confirm the moderate effect of ozone series of current day on the next day when the 1-h difference is observed (more specifically around office hours: 8 am to 17 pm). Finally, the highest peak was observed for forecasted series at 11 am. Intriguingly, we discovered that anticipated values perfectly fit observed values, resulting in the smallest forecasting error. [ABSTRACT FROM AUTHOR]

Oceanic N2O is a major source of atmospheric N2O gas and is involved in global warming and ozone depletion. It is thought to be mainly produced by nitrification, denitrification and nitrifier denitrification processes mediated by ammonia‐oxidizing bacteria, ammonia‐oxidizing archaea (AOA) and denitrifying bacteria. The Bering Sea, especially its continental shelf area, is considered a typical source of atmospheric N2O. During the 7th Chinese National Arctic Research Expedition (CHINARE2016), the distributions of N2O and ammonia‐oxidizing microorganisms (AOOs) in the Bering Sea continental shelf and abyssal basin water were investigated. At a depth of 50∼900 m within the abyssal basin, the in‐situ ammonia oxidation process, particularly performed by AOA, exhibits considerable potential for the formation of supersaturated N2O. Meanwhile, beneath the oxygen minimum zone (depth range is approximately 800∼1,000 m), supersaturated N2O is primarily driven by mixing processes, while the ammonia oxidation mediated by AOA also contributes to a certain extent. In addition, the N2O distribution characteristic exhibits a substantial disparity between the southern and northern Bering Sea shelves, with the former characterized as a mild sink and the latter as a weak source. The water column of the Bering Sea demonstrates a considerable potential for generating supersaturated N2O through ammonia oxidation, as corroborated by the current study. Plain Language Summary: Nitrous oxide (N2O) is an important trace greenhouse gas that also acts as an ozone destroyer. The ocean is one of the main sources of N2O to the atmosphere. As a marginal sea of the Pacific Ocean with high productivity, the distribution mechanism of N2O is very complex affected by water masses mixing and intricate biogeochemical cycle processes. And the N2O flux of Bering Sea has distinct spatio‐temporal variability. In this study, by incorporating previous research conclusions on the nitrogen cycle, we investigate the distribution mechanism of N2O and functional genes of ammonia oxidizing microorganisms in the Bering Sea to elucidate the potential contribution of individual nitrogen cycle processes to N2O supersaturation and which kinds of ammonia oxidation microorganisms are involved in this contribution, thus illustrating the distribution mechanisms of N2O in the northern Bering Sea. The flux of Bering Sea in summer was estimated based on the distribution mechanism of N2O. This findings were helpful to understand the mechanism of N2O metabolism in the Bering Sea and improve the accuracy of Marine N2O flux estimation. Key Points: The source‒sink characteristics of N2O in Bering Sea express obvious spatial and temporal variabilityAmmonia oxidation could potentially play a crucial role in the formation of N2O in the deep waters of the Bering Abyssal BasinThe distribution mechanisms of N2O in the southern and northern shelves of the Bering Sea exhibit distinct characteristic [ABSTRACT FROM AUTHOR]

The distribution of iodine in the surface ocean – of which iodide-iodine is a large destructor of tropospheric ozone (O3) – can be attributed to both in situ (i.e., biological) and ex situ (i.e., mixing) drivers. Currently, uncertainty regarding the rates and mechanisms of iodide (I-) oxidation render it difficult to distinguish the importance of in situ reactions vs ex situ mixing in driving iodine’s distribution, thus leading to uncertainty in climatological ozone atmospheric models. It has been hypothesized that reactive oxygen species (ROS), such as superoxide (O2•−) or hydrogen peroxide (H2O2), may be needed for I- oxidation to occur at the sea surface, but this has yet to be demonstrated in natural marine waters. To test the role of ROS in iodine redox transformations, shipboard isotope tracer incubations were conducted as part of the Bermuda Atlantic Time Series (BATS) in the Sargasso Sea in September of 2018. Incubation trials evaluated the effects of ROS (O2•−, H2O2) on iodine redox transformations over time and at euphotic and sub-photic depths. Rates of I- oxidation were assessed using a 129I- tracer (t1/2 ~15.7 Myr) added to all incubations, and 129I/127I ratios of individual iodine species (I-, IO3-). Our results show a lack of I- oxidation to IO3- within the resolution of our tracer approach – i.e., <2.99 nM/day, or <1091.4 nM/yr. In addition, we present new ROS data from BATS and compare our iodine speciation profiles to that from two previous studies conducted at BATS, which demonstrate long-term iodine stability. These results indicate that ex situ processes, such as vertical mixing, may play an important role in broader iodine species’ distribution in this and similar regions. [ABSTRACT FROM AUTHOR]

Vegetables are an important component of human nutrition that encompasses great species diversity and are very sensitive to unpredictable climatic changes. In recent decades, there has been an increase in the frequency of events like drought, flooding, hightemperature, low temperature, salinity and changes of atmospheric CO2 or ozone level which considerably affect morphological, physiological and biochemical changes in the plants. The occurrences of these types of abiotic stresses lead to membrane damage, oxidative burst, reduction of chlorophyll content and photosynthesis rate which ultimately affect the yield and quality of vegetable crops. The adoption of appropriate crop management practices and climate-resilient cultivars would help immensely in dealing with the adverse impacts of abiotic stresses. Alteration in planting dates, advanced irrigation technology, moisture-saving methods, use of plant growth regulators, use of plant growth promoting rhizobacteria, grafting technology, use of climate resilient cultivars and protected cultivation-like management practices can reduce the impact and intensity of abiotic stress enhance the production as well. Overall in this review, we have summarized the adverse effects of abiotic stresses that are induced by climate change and management strategies that enable to overcome the ill effects and sustain the production of vegetable crops. [ABSTRACT FROM AUTHOR]

Ozone plays an important role in the Earth's atmosphere. It is mainly formed in the tropical stratosphere and is transported by the Brewer–Dobson Circulation to higher latitudes. In the stratosphere, ozone can filter the incoming solar ultraviolet radiation, thus protecting life at the surface. Although tropospheric ozone accounts for only ~10%, it is a powerful GHG and pollutant, harmful to the health of the environment and living beings. Several studies have highlighted biomass burning as a major contributor to the tropospheric ozone budget. Our study focuses on the Natal site (5.40°S, 35.40°W, Brazil), one of the oldest ozone-observing stations in Brazil, which is expected to be influenced by fire plumes in Africa and Brazil. Many studies that examined ozone trends used the total atmospheric columns of ozone, but it is important to assess ozone separately in the troposphere and the stratosphere. In this study, we have used radiosonde ozone profiles and daily TCO measurements to evaluate the variability and changes of both tropospheric and stratospheric ozone separately. The dataset in this study comprises daily total columns of colocalized ozone and weekly ozone profiles collected between 1998 and 2019. The tropospheric columns were estimated by integrating ozone profiles measured by ozone sondes up to the tropopause height. The amount of ozone in the stratosphere was then deduced by subtracting the tropospheric ozone amount from the total amount of ozone measured by the Dobson spectrometer. It was assumed that the amount of ozone in the mesosphere is negligible. This produced three distinct time series of ozone: tropospheric and stratospheric columns as well as total columns. The present study aims to apply a new decomposition method named Empirical Adaptive Wavelet Decomposition (EAWD) that is used to identify the different modes of variability present in the analyzed signal. This is achieved by summing up the most significant Intrinsic Mode Functions (IMF). The Fourier spectrum of the original signal is broken down into spectral bands that frame each IMF obtained by the Empirical Modal Decomposition (EMD). Then, the Empirical Wavelet Transform (EWT) is applied to each interval. Unlike other methods like EMD and multi-linear regression (MLR), the EAWD technique has an advantage in providing better frequency resolution and thus overcoming the phenomenon of mode-mixing, as well as detecting possible breakpoints in the trend mode. The obtained ozone datasets were analyzed using three methods: MLR, EMD, and EAWD. The EAWD algorithm exhibited the advantage of retrieving ~90% to 95% of ozone variability and detecting possible breakpoints in its trend component. Overall, the MRL and EAWD methods showed almost similar trends, a decrease in the stratosphere ozone (−1.3 ± 0.8%) and an increase in the tropospheric ozone (+4.9 ± 1.3%). This study shows the relevance of combining data to separately analyze tropospheric and stratospheric ozone variability and trends. It highlights the advantage of the EAWD algorithm in detecting modes of variability in a geophysical signal without prior knowledge of the underlying forcings. [ABSTRACT FROM AUTHOR]

Every year since the early 1980s, the ozone hole has appeared in late winter/spring over Antarctica. The ozone hole is expected to disappear due to the observed decrease in the concentration of ozone-depleting substances in the stratosphere, which is enforced by the 1987 Montreal Protocol and its subsequent amendments. However, large ozone holes have appeared four years in a row (2020–2023), which may be a signal that Antarctic ozone repair has stopped. Statistical analyses of ozone hole metrics (hole area, minimum total column ozone, ozone mass deficit, and ozone mass deficit per unit area of the hole) are presented to determine how adding the data from these years changes the ozone recovery pattern. Statistically significant trends in the hole metrics were revealed for the short period (2000–2019) but not for the longer period (2000–2023). The modeled time series of metrics from multiple regressions with standard chemical and dynamic explanatory variables indicate that the recovery has slowed since around 2010. Moreover, a sequence of extreme events (wildfires in Australia in the summer of 2019/2020 and the eruption of the Hunga Tonga volcano in January 2022) may have caused additional ozone losses in Antarctica that masked the repair of polar ozone for a while. [ABSTRACT FROM AUTHOR]

Energetic electron precipitation (EEP) associated with pulsating aurora can transfer greater than 30 keV electrons from the outer radiation belt region into the upper atmosphere and can deplete atmospheric ozone via collisions that produce NOx and HOx molecules. Our knowledge of exactly how EEP occurs is incomplete. Previous studies have shown that pitch angle scattering between electrons and lower‐band chorus waves can cause pulsating aurora associated with EEP and that substorms play an important role. In this work, we quantify the timescale of chorus wave decay following substorms and compare that to previously determined timescales. We find that the chorus decay e‐folding time varies based on magnetic local time (MLT), magnetic latitude, and wave frequency. The shortest timescales occur for lower‐band chorus in the 21 to 9 MLT region and compares, within uncertainty, to the energetic pulsating aurora timescale of Troyer et al. (2022, https://doi.org/10.3389/fspas.2022.1032552) for energetic pulsating aurora. We are able to further support this connection by modeling our findings in a quasi‐linear diffusion simulation. These results provide observations of how chorus waves behave after substorms and add additional statistical evidence linking energetic pulsating aurora to substorm driven lower‐band chorus waves. Key Points: Chorus waves exponentially decay with a timescale on the order of an hour in the quiet period following substormsThis decay timescale varies based on magnetic local time, magnetic latitude, and wave frequencyLower‐band chorus waves between 21 and 5 magnetic local time decay with a similar timescale to energetic pulsating aurora electrons after substorms [ABSTRACT FROM AUTHOR]

In urban areas, there has been a recent rise in ground-level ozone. Given its toxicity to both humans and the environment, the investigation of ozone pollution demands attention and should not be overlooked. Therefore, we conducted a study on ozone concentration in three distinct locations within the city of Magurele, Romania. This investigation considered variations in both structure and location during the spring and summer seasons, specifically at a breathing level of 1.5 m above the ground. Our analysis aimed to explore the impact of different locations and meteorological variables on ozone levels. The three measurement points were strategically positioned in diverse settings: within the city, in a forest, and within an industrial area. For these measurements, we used a laser spectroscopy system to determine the system's sensitivity and selectivity and the influence of humidity in the detection of ozone in ambient air, which is a mixture of trace gases and water vapor. During the March–August campaign, the mean values in the three measuring points were 24.45 ± 16.44 ppb, 11.96 ± 3.80 ppb, and 95.01 ± 37.11 ppb. The peak concentrations of ozone were observed during the summer season. A diurnal analysis revealed that the atmospheric ozone levels were higher in the latter part of the day compared to the earlier part. These measurements suggest that the atmospheric temperature plays a significant role in tropospheric ozone production. Additionally, meteorological variables such as wind speed and direction were found to influence the ozone concentration. Remarkably, despite substantial traffic, the ozone levels remained consistently low throughout the entire period within the forested area. This observation may suggest the remarkable ability of trees to mitigate pollution levels. [ABSTRACT FROM AUTHOR]

Nonlinearity in photochemical systems is known to allow self-sustained oscillations, but they have received little attention in studies of planetary atmospheres. Here, we present a unique, self-oscillatory solution for ozone chemistry of an exoplanet from a numerical simulation using a fully coupled, three-dimensional (3D) atmospheric chemistry-radiation- dynamics model. Forced with nonvarying stellar insolation and emission flux of nitric oxide (NO), atmospheric ozone abundance oscillates by a factor of thirty over a multidecadal timescale. As such self-oscillations can only occur with biological nitrogen fixation contributing to NO emission, we propose that they are a unique class of biosignature. The resulting temporal variability in the atmospheric spectrum is potentially observable. Our results underscore the importance of revisiting the spectra of exoplanets over multidecadal timescales to characterizing the atmospheric chemistry of exoplanets and searching for exoplanet biosignatures. There are also profound implications for comparative planetology and the evolution of the atmospheres of terrestrial planets in the solar system and beyond. Fully coupled, 3D atmospheric chemistry-radiation- dynamics models can reveal new phenomena that may not exist in one-dimensional models, and hence, they are powerful tools for future planetary atmospheric research. [ABSTRACT FROM AUTHOR]

We present the most significant results of Russian scientists in the field of atmospheric ozone research for 2019–2022 and examine observations of tropospheric ozone, its distribution and variability on the territory of the Russian Federation, its relation with atmospheric parameters, modeling of formation processes, and its impact on public health. The state of stratospheric ozone over Russia, modeling of processes in the ozonosphere, and methods and instruments being developed are also analyzed. The review is a part of Russia's national report on meteorology and atmospheric sciences, which was prepared for the International Association of Meteorology and Atmospheric Sciences (IAMAS). It has been reviewed and approved at the 28th General Assembly of the International Union of Geodesy and Geophysics (IUGG). [ABSTRACT FROM AUTHOR]

Cooking organic aerosol (COA) is one of the major constituents of particulate matter in urban areas. COA is oxidized by atmospheric oxidants such as ozone, changing its physical, chemical and toxicological properties. However, atmospheric chemical lifetimes of COA and its tracers such as oleic acid are typically longer than that have been estimated by laboratory studies. We tackled the issue by considering temperature. Namely, we hypothesize that increased viscosity of COA at ambient temperature accounts for its prolonged atmospheric chemical lifetimes in wintertime. Laboratory generated COA particles from cooking oil were exposed to ozone in an aerosol flow tube reactor for the temperature range of -20 °C ~ 35 °C. The pseudo-second order chemical reaction rate constants (k2) decreased by orders of magnitude for lower temperatures. The temperature dependence of k2 was fit well by considering diffusion-limited chemical reaction mechanism, suggesting that reduced viscosity was responsible for the decrease in chemical reactivity. In combination with the observed global surface temperature, the atmospheric chemical lifetimes of COA were estimated to be much longer in wintertime (>1 hour) than that in summertime (a few minutes) for temperate and boreal regions. Our present study demonstrates that the oxidation lifetimes of COA particles will need to be parameterized as a function of temperature in the future for estimating environmental impacts and fates of this category of particulate matter. [ABSTRACT FROM AUTHOR]

Large solar coronal mass ejections pose a threat in the near-Earth space. As a cause of extreme periods of space weather, they can damage satellite-based communications and create geomagnetically induced currents in power and energy grids. Further, the solar wind energetic particles can reduce the protecting layer of atmospheric ozone and pose a threat to life on Earth. The large coronal mass ejection (CME) of July 2012, although directed away from the Earth, is often highlighted as a prime example of a potentially devastating super storm. Here we show, based on proton fluxes recorded by the instruments aboard the STEREO-A satellite, that the atmospheric response to the July 2012 event would have been comparable to those of the largest solar proton events of the satellite era. Significant impact on total ozone outside polar regions would require a much larger event, similar to those recorded in historical proxy data sets. Such an extreme event would cause long-term ozone reduction all the way to the equator and increase the size, duration, and depth of the Antarctic ozone hole. The impact would be comparable to predicted drastic and sudden ozone reduction from major volcanic eruptions, regional nuclear conflicts, or long-term stratospheric geoengineering. [ABSTRACT FROM AUTHOR]

Despite offsetting global mean surface temperature, various studies demonstrated that stratospheric aerosol injection (SAI) could influence the recovery of stratospheric ozone and have important impacts on stratospheric and tropospheric circulation, thereby potentially playing an important role in modulating regional and seasonal climate variability. However, so far, most of the assessments of such an approach have come from climate model simulations in which SO 2 is injected only in a single location or a set of locations. Here we use CESM2-WACCM6 SAI simulations under a comprehensive set of SAI strategies achieving the same global mean surface temperature with different locations and/or timing of injections, namely an equatorial injection, an annual injection of equal amounts of SO 2 at 15 ∘ N and 15 ∘ S, an annual injection of equal amounts of SO 2 at 30 ∘ N and 30 ∘ S, and a polar strategy injecting SO 2 at 60 ∘ N and 60 ∘ S only in spring in each hemisphere. We demonstrate that despite achieving the same global mean surface temperature, the different strategies result in contrastingly different magnitudes of the aerosol-induced lower stratospheric warming, stratospheric moistening, strengthening of stratospheric polar jets in both hemispheres, and changes in the speed of the residual circulation. These impacts tend to maximise under the equatorial injection strategy and become smaller as the aerosols are injected away from the Equator into the subtropics and higher latitudes. In conjunction with the differences in direct radiative impacts at the surface, these different stratospheric changes drive different impacts on the extratropical modes of variability (Northern and Southern Annular modes), including important consequences on the northern winter surface climate, and on the intensity of tropical tropospheric Walker and Hadley circulations, which drive tropical precipitation patterns. Finally, we demonstrate that the choice of injection strategy also plays a first-order role in the future evolution of stratospheric ozone under SAI throughout the globe. Overall, our results contribute to an increased understanding of the fine interplay of various radiative, dynamical, and chemical processes driving the atmospheric circulation and ozone response to SAI and lay the foundation for designing an optimal SAI strategy that could form a basis of future multi-model intercomparisons. [ABSTRACT FROM AUTHOR]

Tropical cyclones are one of the biggest threats to life and property. During cyclone period storm surge, flooding, extreme winds, tornadoes and lighting cause significant impacts on life and property and hence affects life of human being to a great extent. Nida was the third tropical cyclone requiring the issuance of tropical cyclone warning signals by the Hong Kong Observatory in 2016 and maximum hourly mean winds of 158 km/hr was recorded in Hong Kong. It affected many cities of China and about 500,000 people, more than 300 houses collapsed and made economic loss of about 500 million RMB. Investigation of lightning discharges around the cyclone track line revealed that the strong lightning activity is noticed during the cyclone period with a super lightning maxima on 30 July and 01 August. The effect of this typhoon on the ionosphere is studied using the TEC data from GPS measurements taken around the cyclone track and satellite based COSMIC measurements. Strong convective activity which is driver for the thunderstorm and gravity waves activity noticed from the negative cloud top temperature as low as −50°C observed from AIRS satellite during the cyclone period. Significant enhancement is atmospheric ozone is observed during the cyclone period which could be attributed to thunderstorm activity present during the cyclone period. The analysis found decrease in GPS‐TEC data at stations around Hong Kong region during the landfall of the cyclone. The magnitude of perturbation in TEC is found larger at stations lying toward right/eastward of the cyclone track as compared to those in the left/westward from the cyclone track. In addition, periodic signatures in ionospheric TEC data were also detected. Continuous wavelet transform to DTEC data has been made to estimate period and found the periodic structure in ionospheric TEC belongs to AGWs with period 9–20 min and frequency 1–2 mHz. Strong scintillation activity as high as S4‐index 1.35 from GPS measurements has been noticed at Sanya station during cyclone period on 02 August which is further confirmed by satellite based measurements from COSMIC. Both measurements show maximum scintillation activity during 1400–1600 UT. The strong scintillation activity as compared to normal days observed during the cyclone period is attributed to lightning induced electric filed as well as generation of AGWs due to deep convection which could act as seed perturbation for generation of ionospheric irregularities by Rayleigh‐Taylor instability mechanism. Key Points: Enhanced atmospheric ozone is observed during cyclone attributed to enhanced lightning activity which may be source of NOxMagnitude of ionospheric perturbation observed along left/right to cyclone track are significantly differStrong scintillation activity compared to normal days from ground and satellite based data are observed during the cyclone period [ABSTRACT FROM AUTHOR]

Being a typical city of heavy industry in west China, Urumqi City is subjected to serious atmospheric ozone pollution in the urban areas due to rapid industrialization and urbanization development. In order to probe into the characteristics of the City' s land-surface ozone pollution, the monitoring data of air pollutants and the meteorological observation data from 2015 to 2019 were applied with the statistical analysis, backward trajectory analysis, potential source contribution factor (PSCF) and concentration weighted trajectory (CWT) to analyze the characteristics and potential source-areas of ozone pollution in Urumqi. The results showed (1) the annual evaluation index of ozone during the period (2015-2019) increased from 118 µg/m³ to 128 µg/m³, and at the same time, the main air pollutant in Urumqi has underwent a transition, i.e, from PM to ozone, the proportion of ozone as a primary pollutant up from 5.8% (2015) to 28.0% (2019). The ozone concentrations variation characteristics of seasons in order of decreasing magnitude: summer>spring>autumn>winter; on the interannual scale, ozone was negatively correlated to NO2 and CO obviously; (2) according to the backward trajectory analysis, the airflow that affected the distribution of atmospheric ozone in Urumqi was characterized by that passing from outbound areas, long-distance migration and containing high ozone concentration. The airflow migration path within the city territory was generally short, not very much influencing the transmission of ozone concentration in Urumqi; and (3) results of using PSCF and the concentration CWT showed that the main source-areas and high ozone-contribution areas that affected the ozone concentration in Urumqi were Changji Prefecture, Tacheng District, Bortala Mongolian Autonomous Prefecture and Altay District; and the distribution of ozone source-areas and high ozone-contribution areas was positively correlated to the seasonal variation of ozone concentrations, which had the evident seasonal characteristics, i.e., the potential source-areas in summer were mainly the moderate source-areas, which widely distributed within the city and had higher ozone contribution, while in winter the whole area of Urumqi turned into a mild source-area; as to spring and autumn the feature of the source-areas fell in between. [ABSTRACT FROM AUTHOR]

This paper explored urban-ozone variability under a minimum local emission condition during the nationwide lockdown, i.e., March 25 to May 31, 2020, focusing on the impacts of meteorology and transported pollutants. We analyzed data from the 27 urban sites across the Indo-Gangetic Plain (IGP). Overall, the concentrations of the primary emission products, viz., NO X (= NO + NO 2 ), CO, and PM 2.5 declined by ∼ 51, ~30, and ~37% respectively. However, the concentration of O 3 , a secondary photochemical product was enhanced by ~ 17% across the IGP compared to the normal time. Interestingly, ~ 30 and ~ 20% enhancements of O 3 concentration were calculated over the upper and central regions of the IGP, respectively but that declined by ∼ 29% over the lower region of the IGP. NO / NO 2 ratio was reduced over the upper (~ 38%) and central (~ 22%) IGP during lockdown period, which could result from the intrusion of the polluted continental air mass. In contrast, relatively clean marine air mass prevailed over the lower IGP and the NO / NO 2 ratio increased by ~ 40%. Also, O 3 forming photochemistry could have been suppressed due to lowered sunlight and temperature during the lockdown period over the lower IGP. [ABSTRACT FROM AUTHOR]

Ozone is a pollutant formed in the atmosphere by photochemical processes involving nitrogen oxides (NOx) and volatile organic compounds (VOCs) when exposed to sunlight. Tropospheric boundary layer ozone is regularly measured at ground stations and sampled infrequently through balloon, lidar, and crewed aircraft platforms, which have demonstrated characteristic patterns with altitude. Here, to better resolve vertical profiles of ozone within the atmospheric boundary layer, we developed and evaluated an uncrewed aircraft system (UAS) platform for measuring ozone and meteorological parameters of temperature, pressure, and humidity. To evaluate this approach, an UAS was flown with a portable ozone monitor and a meteorological temperature and humidity sensor to compare to tall tower measurements in northern Wisconsin. In June 2020, as a part of the WiscoDISCO20 campaign, a DJI M600 hexacopter UAS was flown with the same sensors to measure Lake Michigan shoreline ozone concentrations. This latter UAS experiment revealed low-altitude structure in ozone concentrations in a shoreline environment showing highest ozone at altitudes from 20-100 mAGL. These first such measurements of lowaltitude ozone via UAS in the Great Lakes Region revealed a very shallow layer of ozone rich air lying above the surface. [ABSTRACT FROM AUTHOR]

The results of ground-based microwave observations of ozone in the middle atmosphere in Apatity (67° N, 33° E) during three winters (2017–2018, 2018–2019 and 2019–2020) are presented. Long-term ozone observations were carried out during the period of minimum solar activity for cycles 24 and 25. A mobile microwave spectrometer with an operating frequency of 110.8 GHz was used in the measurements, which allows tracking the behavior of ozone in the middle atmosphere with a 15-min time resolution. The microwave ozone data from ground-based measurements are compared with the MLS/Aura onboard data. Ground and airborne data are compared with the data of contact measurements with ozonesondes at Sodankyla st. (67° N, 27° E). In addition, MLS/Aura data from mid-atmospheric temperature soundings are used to interpret perturbations in the ozone layer associated with sudden stratospheric warmings. A significant influence sudden stratospheric warming on the ozone vertical distribution at altitudes of 22–60 km was found. At the same time, the scale of mesospheric ozone variability (60 km) over Apatity is comparable or exceeds the known model calculations for assessing the impact of solar proton events and auroral electron precipitation on the ozone of the polar regions. [ABSTRACT FROM AUTHOR]

This study uses ozone in the atmosphere column collected by the Aura satellite's ozone monitoring instrument (OMI), to evaluate the ozone pollution status of Japan. Mann–Kendall and slope trend analysis, Hurst index analysis, the potential source contribution factor algorithm, GTWR (geographically and temporally weighted regression model), and the random forest regression model were used in this paper to investigate ozone column concentrations in Japan from 2010 through 2021. The results showed that ozone column concentrations had a significant latitudinal trend over the past 12 years, i.e., concentrations increased with increasing latitude. And the slope has showed a small upward trend over the years (slope = 0.01). The interannual maximum and minimum ozone column concentrations are in 2021 (387.57 DU) and 2015 (241.27 DU), respectively. The monthly maximum and minimum values occur in March (361.60 DU) and October (286.96 DU), with seasonal concentrations in the order of Spring (352.94 DU) > Winter (336.01 DU) > Summer (306.78 DU) > Autumn (296.30 DU). Column ozone concentrations have increased in 69.82% of Japan over the past 12 years. In 2022, the maximum, minimum, and mean ozone column concentrations based on random forest forecasts are 372DU, 278DU, and 334DU, respectively. Pollution sources in Japan are largely derived from pollutants that are transported across borders from the seas around the country or from other countries in the world, with the largest potential source areas being located in the Kanto region. Relative humidity, lift index, and air temperature (in all three seasons except winter) have a negative effect on ozone column concentrations. The positive effects of precipitable water and nitrogen dioxide on ozone column concentrations in the Hokkaido locality and southern Japan were more significant. The contribution of population density and GDP to ozone is small. [ABSTRACT FROM AUTHOR]

Copyright of Riwayat: Educational Journal of History & Humanities is the property of Riwayat: Educational Journal of History & Humanities and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The austral spring in the Southern Hemisphere presents temporary reductions in ozone content mainly in the Antarctic region known as the Antarctic Ozone Hole (AOH). However, studies show an influence in mid-latitude regions, such as southern Brazil, where days with temporary decreases in the total column ozone (TCO) are identified. The main objective of this work is to investigate this influence of AOH on the southern region of Brazil, using data from the TCO and vertical profiles that will help to identify the preferential height at which these decreases occur in southern Brazil, in addition to analyzing the atmospheric dynamic behavior during these events in the period 42 years of data (1979 to 2020). The methodology used comprises the analysis of average daily data of the total column of ozone through ground-based instruments (Brewer Spectrophotometer), satellite data (TOMS and OMI), and to compare reanalysis data from the ECMWF-ERA5, for the identification of events of influence of the AOH on the southern region of Brazil. The analysis of the vertical content of ozone (O 3) data from the TIMED/SABER satellite provides daily data from 15 to 110 km in height and has 19 years of O 3 profiles available in the period from 2002 to 2020. From this, 102 events were identified that influenced Santa Maria (29.4º S; 53.7º W), in the south of Brazil, with a temporary decrease in the ozone content in the period, where between 24.1–28 km of altitude the more significant reductions in O 3 during events. In the dynamic analysis, the stratospheric fields showed an increase in the absolute potential vorticity, mainly in September and October. The conceptual models in the horizontal and vertical section of the atmosphere explain the action of the stratospheric and tropospheric jet during the occurrence of events of decrease in the O 3 content in Santa Maria. It was possible to identify the strong influence on the development of these events through the connection of the stratospheric jet (polar vortex) with the tropospheric jets (polar and subtropical jet) at medium and high levels of the atmosphere. [ABSTRACT FROM AUTHOR]