Earth's Atmosphere Research Articles

Ultrasensitive ion liquid-CNT vdW heterostructure interface via anion-cation pair switch for SO2 detection

Low dimensional van der Waals (vdW) interface shows great advantages for application in vapor detection, such as ultra-high sensitivity and excellent reversibility. However, detection of non-character REDOX capacity and low atmosphere concentration gas such as SO2 is more challengeable. Inspired by the high efficient gas adsorption performance and versatile ion pair combination of ionic liquids, we constructed a vdW heterostructure interface based polymeric ion liquid/SWCNT sensor with different ionic pairs for SO2 detection. Via the composites tuning of SWCNTs and poly(vinylbenzyl 3-ethylimidazolium)-based ionic liquids (PILs) modified with different anions of chloride (Cl-), boron tetrafluoride (BF4-), hexafluorophosphate (PF6-), and bis(trifluoromethanesulfonimide) ions (Tf2N-), stable vdW heterostructure interface was successfully constructed, as proved by SEM, FTIR, XPS and Raman spectra. Upon SO2 adsorption, the distance between the cation/anion was tuned at the heterostructure interface, which triggered great composite tightness changes and thus electrical signal changes of heterostructure interface due to the reversed electron transfer, proved by XPS, Raman spectra and dynamics simulations. Among the sensors composed of the different anions, PIL-BF4-SWCNT exhibited lowest detection limit 20.4 ppt for SO2, which is the best result ever reported. The sensor also show great selectivity, reversibility and stability, with 3.77% response for 512 ppt SO2 within 14 days. The new strategy will open a new way for selective, ultrasensitive and low power vapor detection in complex environment.

Global Impact of Emerging Internetwork Fields on the Low Solar Atmosphere

Small-scale, newly emerging internetwork (IN) magnetic fields are considered a viable source of energy and mass for the solar chromosphere and possibly the corona. Multiple studies show that single events of flux emergence can indeed locally heat the low solar atmosphere through interactions of the upward propagating magnetic loops and the preexisting ambient field lines. However, the global impact of the newly emerging IN fields on the solar atmosphere is still unknown. In this paper, we study the spatiotemporal evolution of IN bipolar flux features and analyze their impact on the energetics and dynamics of the quiet-Sun atmosphere. We use high-resolution, multiwavelength, coordinated observations obtained with the Interface Region Imaging Spectrograph, Hinode, and the Solar Dynamics Observatory to identify emerging IN magnetic fields and follow their evolution. Our observational results suggest that only the largest IN bipoles are capable of heating locally the low solar atmosphere, while the global contribution of these bipoles appears to be marginal. However, the total number of bipoles detected and their impact estimated in this work is limited by the sensitivity level, spatial resolution, and duration of our observations. To detect smaller and weaker IN fields that would maintain the basal flux, and examine their contribution to the chromospheric heating, we will need higher resolution, higher sensitivity, and longer time series obtained with current and next-generation ground- and space-based telescopes.

On the need to assess and mitigate the risk from uncontrolled re-entries of artificial space objects in view of the current and future developments in space activities

From 1 January 2010 to 24 August 2023, 566 orbital stages and 511 spacecraft with a radar cross section >1 m2 have re-entered without control the Earth's atmosphere. The total returned mass was 1650 metric tons, corresponding to a mean of 115 metric tons per year. 77% of the mass belonged to orbital stages, 23% to spacecraft. The uncontrolled re-entries of orbital stages are currently dominated by China, accounting for more than half of the decaying mass, while for spacecraft 2/3 of the mass belongs to American satellites. 60% of the re-entries occurred within 2 years of the launch. The ground casualty expectancy due to orbital stages was always predominant over that from spacecraft, by an average factor of nearly three. From 2010 to 2018, the total casualty probability remained substantially stable, with a mean annual value just over 1%. Since 2019, instead, the annual casualty probability of both spacecraft and orbital stages progressively increased, reaching a total value of around 3% in 2022 and 2023 (extrapolated). Even assuming a stable launch activity, in the coming years, when many of the recently launched spacecraft will start to re-enter, the casualty expectancy of orbital stages will remain basically the same, while that of spacecraft might progressively increase by a factor of 20. This would lead to an annual casualty probability of about 20%, even more in case of a further growth in launch activity, very likely based on current forecasts. The quick implementation of widespread and effective mitigation measures, like controlled de-orbiting and design for demise, is therefore necessary, to prevent the situation from deteriorating too much.

Production and transfer of cosmogenous tritium in the Earth atmosphere in the «PARMA» model

The paper analyses contribution of reactions (n,X) and (p,X) on nitrogen and oxygen nuclei to the production and transfer of cosmogenic tritium in the Earth atmosphere. To calculate the fluxes of secondary protons and neutrons in the nuclear-electromagnetic cascade, the analytical model «PARMA» was used. The model is based on analytical approximations of both numerous experimental data and computer simulation data, and allows one to calculate the fluxes of various particles of secondary cosmic radiation (nucleons, muons, a- and b-particles) with the choice of a given energy range, atmospheric height, geomagnetic cutoff rigidity, solar activity. The problem of vertical turbulent diffusion of tritium in the Earth's atmosphere was solved and the dependence of its concentration on altitude was obtained. Numerical integration of the transport equations was carried out using the integro-interpolation method. An estimate of the total reserve of cosmogenic tritium in the Earth's atmosphere, balanced by turbulent diffusion, decay and cosmogenic formation, was given, which amounted to ~1.9∙1017 Bq. The calculation results show that the earth's atmosphere contains no more than 10% of all cosmogenic tritium. The results are generally consistent with earlier empirical and semi-empirical models confirming that man-made tritium currently accounts for the majority of the total tritium supply

Seismoacoustic measurements of the OSIRIS-REx re-entry with an off-grid Raspberry PiShake

Hypersonic re-entries of spacecraft are valuable analogues for the identification and tracking of natural meteoroids re-entering the Earth's atmosphere. We report on the detection of seismic and acoustic signals from the OSIRIS-REx landing sequence, acquired near the point of peak capsule heating and recorded using a fully off-grid Raspberry PiShake sensor. This simple setup is able to record all the salient features of both the seismic and acoustic wavefields; including the primary shockwave, later reverberations, and possible locally induced surface waves. Peak overpressures of 0.7~Pa and ground velocities of 2x10$^{-6}$~m/s yield lower bound on the air-to-ground coupling factor between 3 and 44~Hz of 1.4x10$^{-6}$m/s/Pa, comparable to results from other re-entries

A study of evaporation duct characteristics in the South China Sea during the Winter of 2017

The evaporation duct (ED) near the sea surface is the most frequent type of duct that traps and redirects electromagnetic waves over longer or shorter distances. This study uses radiosonde data from the South China Sea Two-Island Monsoon Experiment (SCSTIMX) in 2017 and the Weather Research and Forecasting (WRF) model to study the ED and ED height (EDH). We enhanced the vertical resolution to 26 layers in the lowest 134 m. The simulations indicate that EDs were prevalent throughout the South China Sea (SCS) area in winter 2017, where the prevailing surface winds are strong northeasterly. The EDH exhibits diurnal variations and significant variability across the SCS. The WRF simulations of ED and EDH generally agree with observations of the trajectory of Taiwan-O.R.1. Our results indicate that the WRF model can simulate the pattern of ED and EDH over SCS. Results reveal that Yonsei University (YSU) boundary layer (BL) parameterization more accurately simulates the vertical temperature and humidity variations in the lower atmosphere, with stronger winds and higher EDH in most areas. The YSU and the Medium Range Forecast Model (MRF) BL schemes show similar ED patterns to the Taiwan-O.R.1 SCS radiosonde observations but consistently underestimate the EDH. While strong surface winds in the winter SCS may contribute to a higher EDH, the strong surface wind-induced vertical mixing also modifies sea surface air temperature, relative humidity, and vapor pressure, affecting the vertical refractivity. Our results indicate that sea surface air temperature is a more reliable factor affecting EDH in the simulations.

The influence of heterogeneous catalytic processes on the heat flux to the surface and the chemical composition of the shock layer at high-speed flow around blunt bodies

Numerical modeling of the high-speed flow of a multicomponent dissociated gas around a blunt body was carried out for the flow regime corresponding to the thermally stressed point of the gliding trajectory of entry into the Earth's atmosphere in the surface temperature range of 800–2000 K. As boundary conditions, a stage-by-stage model of heterogeneous catalysis of the interaction of dissociated air with the thermal protection material SiO2 was used, previously developed by the authors on the basis of transition state theory and quantum mechanical calculations. The dependence of the modes of heterogeneous chemical reactions on the surface temperature and the density of surface adsorption centers and their influence on the chemical composition of the shock layer and the convective heat flux to the streamlined surface are analyzed. The contributions of individual mechanisms of heterogeneous recombination to the total rate of formation of molecules on the surface are estimated. The possibility of using the density of adsorption sites as an effective parameter when setting boundary conditions on a real thermal protection surface in flow problems is shown.

Theoretical Investigation on Electronic Excited States of the HSO Radical.

HSO radicals play an important role in the photochemical processes in combustion, the atmosphere, and the interstellar medium. In this work, we perform a high-level ab initio study on the electronic excited states of HSO using the internally contracted multireference configuration interaction methods including Davidson correction (icMRCI + Q) in combination with the correlation-consistent basis sets. The molecular geometries, vertical transition energies, oscillator strengths, and electronic configurations of 19 electronic states of HSO are computed. The electronic potential energy curves of HSO along the bond lengths and bond angles are presented. Based on our calculations, the interactions between the electronic states involved in the ultraviolet region and the mechanism of photodissociation are discussed, which will lay a foundation for revealing the dissociation dynamics of gas-phase HSO molecules in outer space and the earth's atmosphere.

Translating genetic findings to epigenetics: identifying the mechanisms associated with aging after high-radiation exposure on earth and in space.

Exposure to radiation is a health concern within and beyond the Earth's atmosphere for aircrew and astronauts in their respective austere environments. The biological effects of radiation exposure from a multiomics standpoint are relatively unexplored and stand to shed light on tailored monitoring and treatment for those in these career fields. To establish a reference variable for genetic damage, biological age seems to be closely associated with the effect of radiation. Following a genetic-based study, this study explores the epigenetic landscape of radiation exposure along with its associative effects on aging processes. We imported the results of the genetics-based study that was a secondary analysis of five publicly available datasets (noted as Data1). The overlap of these genes with new data involving methylation data from two datasets (noted as Data2) following similar secondary analysis procedures is the basis of this study. We performed the standard statistical analysis on these datasets along with supervised and unsupervised learning to create preranked gene lists used for functional analysis in Ingenuity Pathway Analysis (IPA). There were 664 genes of interest from Data1 and 577 genes from Data2. There were 40 statistically significant methylation probes within 500 base pairs of the gene's transcription start site and 10 probes within 100 base pairs, which are discussed in depth. IPA yielded 21 significant pathways involving metabolism, cellular development, cell death, and diseases. Compared to gold standards for gestational age, we observed relatively low error and standard deviation using newly identified biomarkers. We have identified 17 methylated genes that exhibited particular interest and potential in future studies. This study suggests that there are common trends in oxidative stress, cell development, and metabolism that indicate an association between aging processes and the effects of ionizing radiation exposure.

GLOBAL WARMING: CAUSES AND IMPACT ON HEALTH, ENVIRONMENT AND THE BIODIVERSITY CONSERVATION

As atmospheric concentrations of greenhouse gases like carbon dioxide and chlorofluorocarbons rise, the Earth's surface temperature rises, a phenomenon known as global warming. A buildup of atmospheric pollutants like carbon dioxide (CO2) and others absorbs solar radiation and sunlight that has reflected off the Earth's surface, leading to global warming. Pollutants like these, which may cling to Earth's atmosphere for decades or even centuries, prevent the radiation from escaping into space, leading to an increase in global temperatures. Greenhouse gases are those that trap heat; the term "greenhouse effect" describes the impact of gases such carbon dioxide, methane, nitrous oxide, water vapour, and synthetic fluorinated gases. Many species of plants and animals will see their habitats disappear as a result of the climatic shift. Many species go extinct because animals are forced to leave their native habitats. This is just one more way that biodiversity is being negatively affected by global warming. The term "biodiversity" refers to the wide range of species and their variations found in many habitats, such as those found on land, in water, and in deserts. A planet's biodiversity is a measure of its abundance and variety of living forms. It is the planet's most intricate and significant feature. Life could hardly persist in a world devoid of biodiversity. One measure of biological diversity is the variety of species present in an environment, as well as the frequency with which each species occurs. Various degrees of organismal organization are also mirrored in it. Biodiversity is important for the environment and the economy. Food, shelter, fuel, clothes, and a host of other necessities are all provided for by it. Tourism is another source of revenue for it. Therefore, in order to maintain a livelihood throughout time, it is crucial to possess a solid understanding of biodiversity. In spite of biodiversity's advantages, the risks to species and ecosystems are growing at an alarming rate, and almost all of these problems stem from human waste of biological resources, which is in turn caused by climate change, pollution, and incompetent institutions. Preserving biodiversity is crucial for achieving equity both within and between generations. Reforestation, botanical gardens, national parks, biosphere reserves, germplasm banks, and the use of breeding and tissue culture techniques as well as social forestry to reduce pressure on forest resource extraction are some of the current biodiversity conservation measures.

Investigation of temperature and H2 on GePb/Ge multiple quantum well growth

To reveal the growth behavior of GePb/Ge multiple quantum well (MQW) samples, both the influence of growth temperature and H2/Ar atmosphere are investigated by sputtering epitaxy. As the growth temperature increases from 250 °C to 400 °C, Pb atoms become more active and migrate easily to the surface, forming Pb clusters. As a result, the Pb composition in the GePb/Ge MQW is decreased from 3.5% to 1.8%. When H2 is introduced into the chamber, it is found that the MQW disappears and GePb film with uniform Pb distribution is formed. This is possibly because that the introduction of H2 can retain Pb atoms and the GePb is still grown even if the Pb flux is off. The results show that low temperature and H2 atmosphere are effective methods to further break the low solid solubility limit of Pb in Ge.

AI model to improve the mountain boundary layer height of ERA5

The mountain boundary layer height (MBLH) plays a crucial role in determining the exchange of heat, momentum, and composition between the low atmosphere and free troposphere. To obtain accurate quantities of the MBLH, we propose a Data Reinforced Ensemble Machine Learning Model (DREM) to estimate the MBLH using both ERA5 reanalysis multi-variables and thermodynamic profiles observed in two mountainous stations of the foot of Qinling Mountain and the peak of Damaojian mountain in southeast China (Shanghuang site). The observations reveal that the MBLH has resemblances characteristics over the foot of mountains or over the top, featuring daytime high convective boundary layer over 2 km and low stable boundary layer at night about 200 m. But the boundary layer height of EAR5 (ERA5-BLH) has very large error, the Mean Absolute Error (MAE) are nearly 500 m at the valley. The errors between DREM and observations are estimated to be 43% at the peak and 22% at the valley, whereas the corresponding errors from ERA5 reanalysis data are 183% and 70%, respectively. In comparison with the baseline models such as Random Forest (RF), Adaboost, and EM, our statistical results based on all samples demonstrate that DREM can improve the error by 10 m. Subsequent analysis of the Shapley Additive Explanations (SHAP) method demonstrates that the contributions of various meteorological variables in MBLH estimation vary greatly. Among them, Surface Thermal Radiation Downwards (STRD) dominates at both the peak and valley, with lower STRD leading to higher accuracy and vice versa. However, the valley MBLH estimation is not solely determined by thermal factors, but also controlled by dynamic factors and Relative Humidity (RH). Case studies indicate that DREM can significantly minimize deviations, especially at the mountain peak, where it can even capture the abrupt variation of MBLH. In conclusion, the study presents a precise and robust method for estimating the MBLH over complex terrain, which provides an invaluable asset for improving the mountainous weather forecasting, as well as deepening the understanding of the environmental and climatic effects of mountain ecosystems.

Assessing watershed-scale impacts of best management practices and elevated atmospheric carbon dioxide concentrations on water yield

Changes in water yield are influenced by many intersecting biophysical elements, including climate, on-land best management practices, and landcover. Large-scale reductions in water yield may present a significant threat to water supplies globally. Many of these intersecting factors are intercorrelated and confounded, making it challenging to separate the factors' individual contributions to shaping local streamflow dynamics. Comprehensive hydrological models constructed based on a well-established understanding of biophysical processes are often employed to address these matters. However, these models rarely incorporate all relevant factors influencing local hydrological processes, due to the reliance of these models on the latest, albeit limited, state-of-the-art research. For instance, complexities inherent in watershed hydrology, which involve multilayered interactions among potentially many biophysical factors, leave the direct analysis of subtle impacts on water yields measured in-situ largely intractable. Therefore, we propose an innovative approach to assess impacts of elevated atmospheric CO2 concentrations and flow diversion terraces (FDTs) on stream discharge rates at the watershed scale. Initially, we use a comprehensive hydrological model to account for the impacts of major climatic and landuse/landcover factors on changes in field-acquired measurements of water yield. Next, we employ conventional and advanced statistical methods to decompose the residuals of model predictions to facilitate the identification of subtle influences promoted by increases in atmospheric CO2 concentrations and the application of FDTs in an agriculture-dominated watershed. Through this innovative approach, we find that FDTs contributed to a watershed-wide, net water-yield reduction of 188.0 mm (or 28.9 %) from 1992 to 2014. Ongoing increases in ambient CO2 concentrations, which are responsible for an overall reduction in a watershed-level assessment of stomatal conductance, have led to a minor increase in stream discharge rates during the same 23-year period, i.e., 0.45 mm of water yield per year, or 1.6 % overall. Streamflow reductions explicitly caused by regional warming in the area alone, on account of increased evapotranspiration, may be overestimated due to the opposing, synergistic effects on water yield associated with CO2-enrichment of the lower atmosphere and the annual application of FDTs.

Accumulation of absorbing aerosols over the Indian Sector of Southern Ocean during the austral summer: Role of thermal inversions

Optical properties of aerosols and their direct radiative effect were analyzed from columnar Aerosol Optical Depth (AOD) and ambient Black Carbon (BC) mass concentration (MB) estimated during Indian Southern Ocean Expeditions (SOEs), conducted in the austral summers of 2016–17 (SOE-IX) and 2017–18 (SOE-X). The aforementioned observations were supplemented with concurrent vertical soundings of the lower atmosphere. Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) data aided in investigating the vertical distribution of aerosols up to 10 km altitude. The relative contribution of BC aerosols emanating from fossil fuel combustion and biomass burning showed the former to be predominant, as the latter is larger and preferentially scavenged during long-range transport to remote marine regions. The highest values of AOD at 500 nm (AOD500; 0.156 ± 0.026) and MB (90.78 ± 40.11 ng m−3) were encountered in the region between 50 and 60°S. Consequently, the atmospheric clear-sky Aerosol Direct Radiative Effect (ADRE; +3.10 ± 0.38 W m−2) and heating rate (HR; 0.087 ± 0.011 K day−1) were also observed to be the highest in the region. Multiple atmospheric inversions were detected between 40 and 69°S. Although a much lower AOD500 (0.070 ± 0.017) prevailed between 60 and 69°S, the average clear-sky ADRE (+1.56 ± 0.49 W m−2) and HR (0.044 ± 0.014 K day−1) were fairly high. The mean MB in the region was high (68.81 ± 28.40 ng m−3) for the pristine ice-covered region. Low-lying inversions prevented the vertical ventilation and dispersal of BC therein. Simulations of BC-induced atmospheric heating rates at three locations in the coastal Antarctic waters indicated a ≈ 3–5-fold increase, corresponding to an increase in ambient BC from 50 to 300 ng m−3.

A hybrid Bayesian approach for assessment of industry 4.0 technologies towards achieving decarbonization in manufacturing industry

Since the 1st Industrial Revolution, the Earth's atmosphere has warmed due to human activities like deforestation, burning fossil fuels for energy generation, and livestock raising. Without preventative measures, the Earth's atmosphere would warm by 2 °C before the next Industrial Revolution. Thus, it has become crucial to move toward a low-carbon economy. Reaching carbon neutrality means cutting our carbon footprint to zero. Innovative research methods and technologies can play a significant role in supporting the economy in its carbon reduction efforts. Industry 4.0 (I4.0) technologies hold great potential for decarbonizing the economy. However, there is a need to explore and utilize this potential effectively. This study aims to address this by developing a methodology that identifies relevant attributes and critical measures from existing literature, mapping them with I4.0 technologies. Using a MCDM approach, each measure is prioritized based on importance. To better understand the interrelationships between these attributes and I4.0 technologies, the Bayesian Network (BN) method is employed. This approach enables the exploration of dependencies and influences among variables. By implementing this four-stage strategy, economies can make informed decisions and prioritize actions contributing to carbon neutrality while leveraging the benefits of I4.0 technologies. This approach offers a comprehensive framework for guiding economies on their path towards carbon neutrality, considering the potential of I4.0 technologies and the importance of various attributes identified through literature.

A Fast Forward Modelling Method for Simulating Satellite Observations Using Observing Path Tracking

The higher the atmosphere is, the larger the deviations in atmospheric temperature and humidity are between the vertical column atmosphere above the cross-section of a satellite instrument and a ray’s trajectory from the cross-section to the satellite. In general, satellite instruments that observe using cross-orbit scanning result in the difference between the observed radiance and the simulations using this method becoming incrementally larger and larger as the cross-section moves to the edge of the satellite’s orbit. The deviations depend on the distance from the column to the ray trajectory and on the horizontal gradient of variables in the distance. In fact, the horizontal gradient of water vapour is larger than the gradient of temperature in clear scenarios, which could introduce an impact of temperature and water vapour on the simulated radiance of a satellite. In this study, a new method to simulate upgoing and downgoing radiation synchronously was developed, using the observing path tracking method. The conventional vertical initial atmospheric profile (Exp.1) and the profiles along the upgoing and downgoing rays of the satellite’s observation (Exp.2) were established, in order to simulate the observed radiance of MWHS-II of FY-3D using global numerical forecasts with resolutions of 15 km and 25 km. The results showed that, for channels in the oxygen and water vapour absorption line on the microwave spectrum, deviations of the two atmospheric profiles were larger at the scan edge (0.01 K) than those at the nadir (0.001 K), and were larger in the upper atmosphere than in the lower atmosphere. The deviation was usually negative in low-latitude regions and was positive in southern high-latitude regions. Such results were obtained in experiments using both the numerical forecast method with 15 km grids and the forecast method with 25 km grids. Deviations were analysed for representative channels at 118 GHz and 183 GHz. Then, the results indicated that bigger deviations between the two experiments were observed in the water vapour absorption line than in the oxygen absorption line in the microwave spectrum. In conclusion, this indicates that, because of the greater horizontal gradient of water vapour, the stronger localisation of water vapour makes the atmospheric profile along the satellite’s observing ray have more increments in the simulated radiance at the scan edge, compared to the atmospheric column profile.

Climate changes affecting global iodine status.

Global warming is now universally acknowledged as being responsible for dramatic climate changes with rising sea levels, unprecedented temperatures, resulting fires and threatened widespread species loss. While these effects are extremely damaging, threatening the future of life on our planet, one unexpected and paradoxically beneficial consequence could be a significant contribution to global iodine supply. Climate change and associated global warming are not the primary causes of increased iodine supply, which results from the reaction of ozone (O3) arising from both natural and anthropogenic pollution sources with iodide (I-) present in the oceans and in seaweeds (macro- and microalgae) in coastal waters, producing gaseous iodine (I2). The reaction serves as negative feedback, serving a dual purpose, both diminishing ozone pollution in the lower atmosphere and thereby increasing I2. The potential of this I2 to significantly contribute to human iodine intake is examined in the context of I2 released in a seaweed-abundant coastal area. The bioavailability of the generated I2 offers a long-term possibility of increasing global iodine status and thereby promoting thyroidal health. It is hoped that highlighting possible changes in iodine bioavailability might encourage the health community to address this issue.

Development and Testing of a Rocket-Based Sensor for Atmospheric Sensing Using an Unmanned Aerial System.

Measurements of the vertical structure of the lower atmosphere are important to the understanding of air quality. Unmanned Aerial Systems (UASs, drones) can provide low cost, repeatable measurements of the temperature, pressure, and relative humidity. A set of inexpensive sensors controlled with an Arduino microprocessor board were tested on a UAS against a meteorology grade sensor. Two modes of operation for sampling were tested: a forward moving sampler and a vertical ascent sampler. A small particle sensor (Sensiron SPS30) was integrated and was capable of retrieving vertical aerosol distributions during an inversion event. The thermocouple-based temperature probe and the relative humidity measurement on the Bosch BME280 sensor correlated well with the meteorological sensor. The temperature and relative humidity sensors were then deployed on a rocket sounding platform. The rocket sounding system performed well up to a height of 400 m. The inexpensive sensors were found to perform adequately for low-cost development and uses in education and research.

Ring current electron precipitation during the 17 March 2013 geomagnetic storm: Underlying mechanisms and their effect on the atmosphere

Electron and ion fluxes at energies of ∼10 keV−1 MeV can change by orders of magnitude during geomagnetically active periods. This can lead to intensification of particle precipitation into the Earth's atmosphere. The process further affects atmospheric chemistry, which may impact weather and climate on the Earth’s surface. In this study, we concentrate on ring current electrons, and investigate precipitation mechanisms using a numerical model based on the Fokker-Planck equation. We focus on a study of the main precipitation mechanisms, and their connection with atmospheric parameters. We investigate the 17 March 2013 storm using the convection–diffusion 4-Dimensional Versatile Electron Radiation Belt (VERB-4D) code, that allows us to quantify the impact of the storm on the electron ring current, and the resulting electron precipitation. We validate our results against observations from the Polar Operational Environmental Satellites (POES) mission, the low Earth orbiting meteorological satellites National Oceanic and Atmospheric Administration (NOAA-15,-16,-17,-18,-19), and Meteorological Operational Satellite MetOp-02, as well as the Van Allen Probes, and produce a data set of precipitating fluxes that covers an energy range from 10 keV to 1 MeV. We calculate the altitude-dependent atmospheric ionization rates, a prerequisite for atmospheric models to estimate effects of geomagnetically active periods on chemical and physical variability of the atmosphere at high latitudes. Atmospheric ionization rates are validated against Atmospheric Ionization during Substorm (AIMOS 2.1-Aisstorm) and Special Sensor Ultraviolet Spectrographic Imagers (SSUSI) values, and show good agreement at high geomagnetic latitudes during the storm time.

Sodium fluoride enables room-temperature synthesis of dimethyl carbonate

Carbon dioxide (CO2) in the atmosphere of the Earth represents an abundant and largely free source of carbon, which remains heavily underestimated nowadays. The disbalance between the emission and utilization of CO2 puts the sustainable development of humanity at risk because of its possible correlation with global climate change. The valorization of CO2 is an important strategy to attend to the above-mentioned challenges. CO2 can be converted to dimethyl carbonate by grafting to methanol (CH3OH) in the presence of the catalyst. The presently known catalytic solutions require high temperatures and pressures to be employed. Herein, we report sodium fluoride as a new catalyst offering an unprecedentedly low activation barrier, 23 kJ/mol, for the carboxylation of CH3OH. The fluoride anion coordinates the hydroxyl hydrogen of CH3OH thanks to forming a very strong H-bond. Upon the collision with CO2, the proton detaches, and CO2 grafts to CH3O* while becoming the carboxyl group. The reaction finishes by methylating CH3OC(O)O– via the methyl radical originating from another CH3OH molecule (esterification stage). The hydrogen fluoride molecule is an intermediate in this reaction providing the proton and fostering esterification. The subsequent in-lab experiments showed that much milder conditions can be used to synthesize DMC out of CH3OH. Under 80 °C and 40 bar, we obtained an outstanding DMC yield of 21.1 %. However, the synthesis was also possible at lower temperatures giving DMC yields of 16.3 % at 65 °C, 14.7 % at 55 °C, and 10.8 % at 25 °C. The unprecedented possibility to obtain a non-negligible production of an organic carbonate at room temperature represents a cornerstone advance in the field of CO2 valorization and promises huge energy savings. Given the current global amount of the yearly prepared DMC amounting to over one million tons and the demand for this chemical by emerging chemical technologies, the achieved result is deemed to be of paramount importance. The exemplified catalytic mechanism is also interesting in the context of other syntheses, in which a low-energetic production of the methoxy moieties is a cornerstone.