Environmental science: atmospheres最新文献

Aerosols formed and grown by gas-to-particle processes are a major contributor to smog and haze in megacities, despite the competition between growth and loss rates. Rapid growth rates from ammonium nitrate formation have the potential to sustain particle number in typical urban polluted conditions. This process requires supersaturation of gas-phase ammonia and nitric acid with respect to ammonium nitrate saturation ratios. Urban environments are inhomogeneous. In the troposphere, vertical mixing is fast, and aerosols may experience rapidly changing temperatures. In areas close to sources of pollution, gas-phase concentrations can also be highly variable. In this work we present results from nucleation experiments at −10 °C and 5 °C in the CLOUD chamber at CERN. We verify, using a kinetic model, how long supersaturation is likely to be sustained under urban conditions with temperature and concentration inhomogeneities, and the impact it may have on the particle size distribution. We show that rapid and strong temperature changes of 1 °C min⁻¹ are needed to cause rapid growth of nanoparticles through ammonium nitrate formation. Furthermore, inhomogeneous emissions of ammonia in cities may also cause rapid growth of particles.

Ensuring environmental justice necessitates equitable access to air quality data, particularly for vulnerable communities. However, traditional air quality data from reference monitors can be costly and challenging to interpret without in-depth knowledge of local meteorology. Low-cost monitors present an opportunity to enhance data availability in developing countries and enable the establishment of local monitoring networks. While machine learning models have shown promise in atmospheric dispersion modelling, many existing approaches rely on complementary data sources that are inaccessible in low-income areas, such as smartphone tracking and real-time traffic monitoring. This study addresses these limitations by introducing deep learning-based models for particulate matter dispersion at the neighbourhood scale. The models utilize data from low-cost monitors and widely available free datasets, delivering root mean square errors (RMSE) below 2.9 μg m⁻³ for PM₁, PM_2.5, and PM₁₀. The sensitivity analysis shows that the most important inputs to the models were the nearby monitors' PM concentrations, boundary layer dissipation and height, and precipitation variables. The models presented different sensitivities to each road type, and an RMSE below the regional differences, evidencing the learning of the spatial dependencies. This breakthrough paves the way for applications in various vulnerable localities, significantly improving air pollution data accessibility and contributing to environmental justice. Moreover, this work sets the stage for future research endeavours in refining the models and expanding data accessibility using alternative sources.

Our estimates show that ‘proven reserves’ of fossil fuels in 2022, would generate an estimated 4777 Gt of CO₂ after allowing for non-fuel uses. This quantity already could ‘bust CO₂ budgets’ for IPCC RCP2.6, RCP4.5, and RCP6.0 and is approaching the range for RCP8.5. Notwithstanding these results, fossil fuel companies are still exploring and bringing new reserves onstream. We discuss the reasons behind this, and propose some policy options for governments as they address this situation.

Charging of the ice–vapor interface is a well-studied topic in ice physics and atmospheric electrification. However, these effects were not yet considered to examine chemical processes in snow in polar regions because electric potentials at ice surfaces have so far been considered insufficient to initiate chemical reactions and processes. In this review, we analyze literature data to estimate levels of electrification in snow and other frozen objects that can be caused by different processes occurring at the Earth's surface. This analysis demonstrates that threshold values of electric field strength can be exceeded for the appearance of corona discharges and even for the formation of Rayleigh jets due to combined effects of different meteorological and physical processes. The accumulation of electrical charges can lead to different chemical modifications such as electroosmotic phenomena or the accumulation of impurities from the atmosphere in growing ice crystals. Moreover, highly energetic states that occur and dissipate in microseconds as “hot spots” have the potential to initiate free radical processes and even the production of charged aerosols. The review also discusses in detail selected field observations to point out how processes driven by electrical charging may help to interpret these observations, which are at least partly inconsistent with our present understanding of snow and ice chemistry. Finally, some approaches are presented how these effects can be studied in field and laboratory experiments. A further development of this new field at the intersection of ice physics and snow chemistry seems very promising for a better understanding of relevant chemical processes related to the cryosphere.

Exposure to PM_2.5 emitted from traditional biomass cookstoves is a significant health risk for nearly one-third of the global population. Improved cookstoves aim to reduce pollutant emissions, but there is limited evidence of whether PM_2.5 toxicity is also reduced. Using the dithiothreitol (DTT) assay to measure the potential for PM_2.5 chemical components to induce oxidative stress through antioxidant depletion and/or oxidant generation, we characterized the mass- and volume-normalized DTT activity of PM_2.5 emitted from a traditional three-stone fire cookstove and three improved cookstoves burning wood or charcoal fuels. Although improved cookstoves typically yield lower PM_2.5 mass concentrations compared to traditional three-stone cookstove, exposure to DTT active PM_2.5 is not always reduced due to increases in mass-normalized DTT activity. A notable decrease in DTT active PM_2.5 exposure (by 67%) was only observed for a forced-draft improved cookstove burning wood, where low PM_2.5 mass concentration offsets the increased mass-normalized DTT activity. Additionally, elemental carbon and water-soluble organic matter were identified as key predictors of volume-normalized DTT activity. Compared to wood, the use of charcoal led to a 61–86% reduction in exposure to DTT active PM_2.5, owing to both lower PM_2.5 mass concentration and mass-normalized DTT activity. This further supports a proposed strategy whereby biomass fuel treatment can potentially reduce household exposure to toxic PM_2.5. Collectively, our findings emphasized the need to consider not only the mass concentration but also the toxic properties of PM_2.5 when evaluating the health impacts of cookstoves and fuels.

Correction for ‘Emerging investigator series: aqueous oxidation of isoprene-derived organic aerosol species as a source of atmospheric formic and acetic acids’ by Kelvin H. Bates et al., Environ. Sci.: Atmos., 2023, 3, 1651–1664, https://doi.org/10.1039/D3EA00076A.

NO_x is released from sunlit snowpack surfaces, and this considerably influences the oxidizing capacity of the clean boundary layer atmosphere in Antarctic and Arctic regions and the potential interpretation of the historical atmospheric composition recorded in the ice core. The Tibetan Plateau is an important snow-covered region in the northern midlatitudes, with strong solar radiation and relatively high NO₃⁻ in snow/ice. Released NO_x on the glacier surface of the Tibetan Plateau should be strong. To confirm this hypothesis, field observations were performed at 4600 m above the sea level in Qiyi Glacier in late August 2004. The surface ultraviolet-B (UVB) radiation level reached >4.5 W m⁻² and was increased by the strong reflection of snow/ice and clouds against the Sun and strengthened by the topographical effect. The concentrations of NO₃⁻ and NH₄⁺ in water from melting snow were hardly detected, but the average concentration (±1σ) of NO₃⁻ in snow samples was 8.7 ± 2.7 μmol L⁻¹. Strong correlations were observed between NO_x (NO₂) mixing ratios and UVB radiation levels in the Tibetan glacier. Vertical experiments revealed a negative gradient of NO_x (NO₂) mixing ratios from the glacier snow surface to a height of 30 cm. As a result of the high levels of UV radiation and high NO₃⁻ concentrations in snow/ice, the mixing ratios of NOx released by fresh snow in Qiyi Glacier in late August reached several parts per billion (ppbv) and were approximately one order of magnitude higher than those observed in polar regions. This observation provides direct evidence to support the research hypothesis and confirms the release of high concentrations of NOx in the boundary layer of the highland glaciers and snow surfaces.

Given the rise in global mean temperature as a direct consequence of increasing levels of greenhouse gases (GHG) in the atmosphere, a variety of climate engineering approaches, including stratospheric aerosol injection (SAI), have been proposed. Often criticized as a distraction from global efforts towards reducing GHG emissions, SAI aims to increase the Earth's albedo by seeding aerosols in the lower stratosphere. Inspired in part by observations of temporary cooling of the Earth's surface following major volcanic eruptions which introduced significant loadings of sulfate particles into the stratosphere, SAI has been explored extensively in modeling studies. The cooling effect may be accompanied by other significant consequences including stratospheric heating, stratospheric ozone (O₃) depletion, and reduced global mean precipitation. In order to understand the potential environmental and climate impacts of SAI, we review the state of the knowledge regarding these issues, starting from an aerosol science perspective. We summarize aerosol radiative properties and the role they play in defining the optimal chemical and physical aerosol characteristics for SAI, and their implications for lower stratospheric warming. We then review in depth the impacts of stratospheric aerosol heterogeneous chemistry on global O₃ levels. We review SAI modeling studies as well as their uncertainties, in comparison to the observed environmental and climate impacts of volcanically derived sulfate aerosols, including impacts on global temperature, stratospheric warming, and hydrological cycle. We also briefly discuss the current governance and economic considerations of the application of SAI and raise essential questions from both research and social standpoints that should be addressed before SAI is deployed for climate change mitigation.

Uncrewed Aircraft Systems (UAS) are becoming prevalent in a wide variety of meteorological investigations. UAS fill an important atmospheric observational gap, namely observations between ground-based sensors and higher altitudes where manned aircraft can safely operate. This paper explores the hardware and software design used for a multi-vehicle atmospheric data collection campaign. The Mobility Virtual Environment (MoVE) is a software framework designed specifically to collect data from multiple vehicles and present a coherent, summary view of a complex scenario. Using both a 2D map and a live updating table, multiple vehicles can be monitored simultaneously to make real-time decisions and quickly assess the mission's effectiveness. MoVE is the software framework used to gather live telemetry inputs before, during, and after flight. MoVE is also the set of tools used to post-process multiple data logs from days of flight experiments into 3D and 4D visualizations over the surrounding terrain. The results are visualizations of otherwise invisible quantities like T, P, RH, and especially vector wind velocities, , captured during flight with drone-based sensors. The open-source software and procedures described here can help the atmospheric research, and broader scientific community, achieve greater understanding when using drone-based sensors.

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