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For some seventy years, rulings made by judges sitting at nisi prius were regularly reported, despite those reports being held in low esteem by the legal profession and such rulings being regarded as of little value as precedents. This article considers why those rulings, at least on matters of substantive law, were rejected as authorities, and sets out the reasons why they were nevertheless reported and cited. The article explains that the principal purposes of these reports were to introduce new members of the profession to the practicalities of preparing cases for trial, and to provide some authority, however slight, to cite in court. The article also explains that, while nisi prius rulings on substantive law were cited by nineteenth century judges, they were used differently to decisions of courts in banc. The greater authority of such rulings on points of evidence, at least up to the mid-nineteenth century, is also explored. The article concludes by examining the tendency of more recent judges to ascribe greater weight to nisi prius rulings than their nineteenth century counterparts, due to the modern profession's ignorance of the former difference in the treatment of nisi prius rulings and the decisions of courts in banc. [ABSTRACT FROM AUTHOR]

Coastal wetlands play a significant role in the storage of "blue carbon," indicating their importance in the carbon biogeochemistry in the coastal zone and in global climate change mitigation strategies. We present airborne eddy covariance observations of CO2 and CH4 fluxes collected in southern Florida as part of the NASA BlueFlux mission during April 2022, October 2022, February 2023, and April 2023. The flux data generated from this mission consists of over 100 flight hours and more than 6,000 km of horizontal distance over coastal saline and freshwater wetlands. We find that the spatial and temporal heterogeneity in CO2 and CH4 exchange is primarily influenced by season, vegetation type, ecosystem productivity, and soil inundation. The largest CO2 uptake fluxes of more than 20 μmol m−2 s−1 were observed over mangroves during all deployments and over swamp forests during flights in April. The greatest CH4 effluxes of more than 250 nmol m−2 s−1 were measured at the end of the wet season in October 2022 over freshwater marshes and swamp shrublands. Although the combined Everglades National Park and Big Cypress National Preserve region was a net sink for carbon, CH4 emissions reduced the ecosystem carbon uptake capacity (net CO2 exchange rates) by 11%–91%. Average total net carbon exchange rates during the flight periods were −4 to −0.2 g CO2‐eq m−2 d−1. Our results highlight the importance of preserving mangrove forests and point to potential avenues of further research for greenhouse gas mitigation strategies. Plain Language Summary: Coastal wetlands play a crucial role in trapping and storing carbon, aiding in climate change adaptation and mitigation efforts. Carbon dioxide (CO2) uptake and methane (CH4) emissions were measured from an aircraft over wetlands of southern Florida during different times of the year. Season, vegetation, ecosystem productivity, and water depth were found to have a large influence on carbon exchange. Mangroves with the largest canopy heights showed the highest CO2 uptake, whereas CH4 emissions peaked during the wet season over freshwater marshes where surface water depths were the greatest. CH4 emissions diminished the overall carbon uptake capacity of southern Florida. Results emphasize the importance of preserving coastal wetland ecosystems and suggest potential directions for further research aimed at mitigating greenhouse gas emissions. Key Points: Airborne eddy covariance measurements reveal heterogeneity in CH4 and CO2 fluxes across southern FloridaVariability in carbon fluxes was primarily driven by vegetation types, season, ecosystem productivity, and soil inundationSouthern Florida served as a net carbon sink during all flight periods with CH4 emissions offsetting CO2 deposition by 11%–91% [ABSTRACT FROM AUTHOR]

Controlled formation of mixed-metal bimetallics was achieved via two derivatised 1,10-phenanthroline ligands bearing an imino- or amino-phosphine appendage at the 5-position. Selective coordination of the phen group to the [Re(CO)3Cl] core was achieved enabling precise construction of bimetallic complexes with a second rhenium centre or with gold. The mixed Ru/Au complex was similarly obtained with the imino-phosphine but access to the heterobimetallic iridium systems required prior formation of the P-bound gold complexes subsequent to the introduction of the [Ir(Ppy)2]+ fragment. The Re/Pd, Re/Pt, Ir/Pd and Ir/Pt compounds were prepared from the combination of κ-N′′,P-Pd(Pt)Cl2 and the appropriate rhenium or iridium precursors. Spectroscopic and theoretical analyses have been employed to investigate the structural and electronic impact of the second metal. [ABSTRACT FROM AUTHOR]

Ring size-dependent diastereoselective coordination of unsymmetrical diamines containing one azacyclic nitrogen and one exocyclic nitrogen to [(η5-C5Me5)MCl]+ cores where M = Rh, Ir and [Ru(η6-cymene)Cl]+ is reported herein. Total stereoselectivity was observed with the six- and seven-membered azacycles, whereas the five-derivative proved poorly selective. All complexes were active for transfer hydrogenation but showed no enantioselectivity with prochiral ketones. [ABSTRACT FROM AUTHOR]

Observations of March 2024 Arctic (63°N–90°N) total column ozone set a record high of 477 Dobson Units (DU) against the 1979–2023 satellite era time series. It was about 60 DU higher than average and 6 DU higher than the previous March 1979 471 DU record. Daily Arctic ozone was above average for every day in March 2024, and set record highs from 11–26 March 2024. Microwave Limb Sounder data show this record ozone anomaly was concentrated in the lower stratosphere (10–30 km). These record values developed over the 2023–2024 winter and can be associated with vertically propagating planetary‐scale wave events that caused significant stratospheric warmings. These wave events forced poleward and downward ozone advection into the lower stratosphere, leading to record column ozone levels. The above average levels persisted through August 2024 and across the northern hemisphere. Plain Language Summary: Man‐made chlorofluorocarbons (CFCs) depleted the Earth ozone layer. The 1987 Montreal Protocol curbed CFC growth, but because CFCs have multi‐decadal lifetimes, Arctic ozone is not expected to recover back to 1980 levels until ∼2045. Current high CFC levels combined with persistent and cold polar vortices led to severe Arctic ozone spring depletion in 1997, 2011, and 2020. Contrary to expectations, March 2024 Arctic ozone showed a record high level, dramatically contrasting against the severe depletion events. Meteorological and ozone profile information show that the exceptional 2024 ozone was mainly found in the lowermost Arctic stratosphere, in association with record high lowermost stratospheric temperatures. The ozone levels incrementally increased during the 2023–2024 winter because of large‐scale weather systems that propagated from the troposphere into the stratosphere. Collectively, these weather systems also were at a record level, moving higher ozone concentrations from the mid‐latitudes and upper stratospheric into the Arctic region. This record high ozone would likely have not occurred if CFC levels had not begun slowly declining in response to the Montreal Protocol. Given the absence of high Arctic ozone since the 1970s, the March 2024 record high should be considered a positive harbinger of the future Arctic ozone layer. Key Points: Arctic total column ozone in March 2024 set a record high for the 1979‐present periodPolar lower stratosphere temperatures also set a record high in March 2024 in the MERRA‐2 reanalysis dataA record amount of Rossby waves propagating upward from the troposphere caused the record total ozone and lower stratospheric temperature [ABSTRACT FROM AUTHOR]

The literature presents different views on how the stratosphere influences variability in surface nitrous oxide (N 2 O) and on whether that influence is outweighed by surface emission changes driven by the El Niño–Southern Oscillation (ENSO). These questions are investigated using a chemistry–climate model with a stratospheric N 2 O tracer; surface and aircraft-based N 2 O measurements; and indices for ENSO, polar lower stratospheric temperature (PLST), and the stratospheric quasi-biennial oscillation (QBO). The model simulates well-defined seasonal cycles in tropospheric N 2 O that are caused mainly by the seasonal descent of N 2 O-poor stratospheric air in polar regions with subsequent cross-tropopause transport and mixing. Similar seasonal cycles are identified in recently available N 2 O data from aircraft. A correlation analysis between the N 2 O atmospheric growth rate (AGR) anomaly in long-term surface monitoring data and the ENSO, PLST, and QBO indices reveals hemispheric differences. In the Northern Hemisphere, the surface N 2 O AGR is negatively correlated with winter (January–March) PLST. This correlation is consistent with an influence from the Brewer–Dobson circulation, which brings N 2 O-poor air from the middle and upper stratosphere into the lower stratosphere with associated warming due to diabatic descent. In the Southern Hemisphere, the N 2 O AGR is better correlated to QBO and ENSO indices. These different hemispheric influences on the N 2 O AGR are consistent with known atmospheric dynamics and the complex interaction of the QBO with the Brewer-Dobson circulation. More airborne surveys extending to the tropopause would help elucidate the stratospheric influence on tropospheric N 2 O, allowing for better understanding of surface sources. [ABSTRACT FROM AUTHOR]

The Chilean volcano Cerro Hudson erupted between August 8th and 15th, 1991, injecting between 1.7 and 2.9 Tg of SO2 into the upper troposphere and lower stratosphere. We simulate this injection using the Goddard Earth Observing System Earth system model with detailed sulfur chemistry and sectional aerosol microphysics, focusing on the resulting aerosols and their contribution to the 1991 Antarctic Austral Springtime ozone hole. The simulations show a column ozone deficit (12 DU) in the Southern Hemisphere vortex collar region. The majority of this effect is between 10 and 20 km and due to heterogeneous chemistry. The model shows a 26% decrease in ozone from background levels at these altitudes, compared with in‐situ observations of a 50% decrease. Above 20 km, the dynamical response to the eruption also causes lower ozone values, a novel modeling result. This experiment highlights potential interactions between proposed solar radiation management geoengineering aerosols and volcanic eruptions. Plain Language Summary: We simulated the August 1991 eruption of Chilean volcano Cerro Hudson. Cerro Hudson erupted 2 months after the June 15th eruption of Pinatubo which was one of the largest observed eruptions. The combination of these two eruptions impacted the atmosphere by injecting volcanic aerosol which are well represented by our model. In the case of Cerro Hudson, the simulations show that the volcanic plume may have impacted the 1991 Antarctic ozone hole, both by directly impacting the chemistry of ozone depletion and by altering the dynamics of the atmosphere, slowing down the normal breakdown of the ozone hole caused by changes in weather. The interaction between Cerro Hudson and Pinatubo shown here also reveal a need for more research in how potential goengineering scenarios would interact with volcanic eruptions. Key Points: The August 1991 eruption of Cerro Hudson is simulated using a model with detailed aerosol microphysics and stratospheric chemistryThe model shows skill in simulating the satellite and in‐situ observations of the volcanic plumeThese simulations present a prima facie case that this eruption contributed to the anomalously high 1991 Austral Springtime ozone loss [ABSTRACT FROM AUTHOR]

The controlled formation of mixed-metal bimetallics was realised through use of a fac-[Re(CO)3(N,N′-bpy-P)Cl] complex bearing an exogenous 2,4,6-trioxa-1,3,5,7-tetramethyl-8-phosphaadamantane donor at the 5-position of the bpy. The introduction of gold, silver, and rhodium with appropriate secondary ligands was readily achieved from established starting materials. Restricted rotation about the C(bpy)-P bond was observed in several of the bimetallic complexes and correlated with the relative steric bulk of the second metal moiety. Related chemistry with the 6-substituted derivative proved more limited in scope with only the bimetallic Re/Au complex being isolated. [ABSTRACT FROM AUTHOR]

The quasi-biennial oscillation (QBO) was unexpectedly disrupted for only the second time in the historical record during the 2019/2020 boreal winter. As the dominant mode of atmospheric variability in the tropical stratosphere and a significant source of seasonal predictability globally, understanding the drivers behind this unusual behaviour is very important. Here, novel data from Aeolus, the first Doppler wind lidar (DWL) in space, are used to observe the 2019/2020 QBO disruption. Aeolus is the first satellite able to observe winds at high resolution on a global scale, and it is therefore a uniquely capable platform for studying the evolution of the disruption and the broader circulation changes triggered by it. This study therefore contains the first direct wind observations of the QBO from space, and it exploits measurements from a special Aeolus scanning mode, implemented to observe this disruption as it happened. Aeolus observes easterly winds of up to 20 m s -1 in the core of the disruption jet during July 2020. By co-locating with radiosonde measurements from Singapore and the ERA5 reanalysis, comparisons of the observed wind structures in the tropical stratosphere are produced, showing differences in equatorial wave activity during the disruption period. Local zonal wind biases are found in both Aeolus and ERA5 around the tropopause, and the average Aeolus-ERA5 Rayleigh horizontal line-of-sight random error is found to be 7.58 m s -1. The onset of the QBO disruption easterly jet occurs 5 d earlier in Aeolus observations compared with the reanalysis. This discrepancy is linked to Kelvin wave variances that are 3 to 6 m 2 s -2 higher in Aeolus compared with ERA5, centred on regions of maximum vertical wind shear in the tropical tropopause layer that are up to twice as sharp. The enhanced lower-stratospheric westerly winds which are known to help disrupt the QBO, perhaps with increasing frequency as the climate changes, are also stronger in Aeolus observations, with important implications for the future predictability of such disruptions. An investigation into differences in the equivalent depth of the most dominant Kelvin waves suggests that slower, shorter-vertical-wavelength waves break more readily in Aeolus observations compared with the reanalysis. This analysis therefore highlights how Aeolus and future DWL satellites can deepen our understanding of the QBO, its disruptions and the tropical upper-troposphere lower-stratosphere region more generally. [ABSTRACT FROM AUTHOR]

Summary: In this article, we summarize the deployment of the Air Force Weather (AFW) HPC11 system at Oak Ridge National Laboratory (ORNL) including the process followed to successfully complete acceptance testing of the system. HPC11 is the first HPE/Cray EX 3000 system that has been successfully released to its user community in a federal facility. HPC11 consists of two identical 800‐node supercomputers, Fawbush and Miller, with access to two independent and identical lustre parallel file systems. HPC11 is equipped with Slingshot 10 interconnect technology and relies on the HPE Performance Cluster Manager software for system configuration. ORNL has a clearly defined acceptance testing process used to ensure that every new system deployed can provide the necessary capabilities to support user workloads. We worked closely with HPE and AFW to develop a set of tests that used the United Kingdom's Meteorological Office's Unified Model and 4‐dimensional variational data assimilation. We also included benchmarks and applications from the Oak Ridge Leadership Computing Facility portfolio to fully exercise the HPE/Cray programming environment and evaluate the functionality and performance of the system. Acceptance testing of HPC11 required parallel execution of each element on Fawbush and Miller. In addition, careful coordination was needed to ensure successful acceptance of the newly deployed lustre file systems alongside the compute resources. In this work, we present test results from specific system components and provide an overview of the issues identified, challenges encountered, and the lessons learned along the way. [ABSTRACT FROM AUTHOR]

The January 2022 eruption of the Hunga Tonga‐Hunga Ha'apai underwater volcano injected a large amount of water vapor into the mid‐stratosphere. This study uses model simulations to investigate the resulting stratospheric impacts out to 2031. Maximum radiatively‐driven model temperature changes occur in the Southern Hemisphere (SH) subtropics in April–May 2022, with warming of ∼1 K in the lower stratosphere and cooling of 3 K in the mid‐stratosphere. The radiative cooling combined with adiabatic cooling driven by the quasi‐biennial oscillation meridional circulation explains the near‐record cold anomaly observed in the SH subtropical mid‐stratosphere. Projected ozone responses maximize in 2023–2024 as the water vapor plume is transported globally throughout the stratosphere and mesosphere. The excess H2O increases the OH radical, causing a negative global ozone response (2%–10%) in the upper stratosphere and mesosphere due to increased odd hydrogen‐ozone loss, and a small positive ozone response (0.5%–1%) in the mid‐stratosphere due to interference of the NOx catalytic loss cycle by the additional OH. In the lower stratosphere, the excess H2O is projected to increase polar stratospheric clouds and springtime halogen‐ozone loss, enhancing the Antarctic ozone hole by 25–30 DU in 2023. Arctic impact is small, with maximum additional ozone loss of 4–5 DU projected in spring 2024. These responses diminish after 2024 to be quite small by 2031, as the excess H2O is removed from the stratosphere with a 2.5‐year e‐folding time. Given the year‐to‐year variability of the stratosphere, the magnitudes of these ozone responses may be below the threshold of detectability in observations. Plain Language Summary: Stratospheric ozone protects Earth's biosphere from harmful ultraviolet radiation, and along with water vapor, are key components in determining temperature and chemistry of the atmosphere. The January 2022 eruption of the Hunga Tonga‐Hunga Ha'apai underwater volcano in the South Pacific injected water vapor into the atmosphere, increasing stratospheric water vapor by 10%. In this study, we use computer simulations of the stratosphere to project how this additional water vapor changed temperature and ozone in the months and years following the eruption. The water vapor cooled the middle stratosphere (roughly 14–25 miles above Earth's surface) and warmed the lower stratosphere (6–14 miles above the surface), with the largest changes of 2–5° Fahrenheit in March–June 2022, several months after the eruption. The additional water vapor modified chemical processes that affect stratospheric ozone, leading to a projected 10%–15% enhancement in the Antarctic ozone hole. This ozone hole enhancement is estimated to have maximized in October 2023, almost 2 years after the eruption, due to the slow circulation of stratospheric water vapor from the subtropics to the polar region. These impacts are expected to diminish after 2024 as the excess water vapor is slowly removed from the atmosphere by natural processes. Key Points: The water vapor injection from the Hunga Tonga eruption impacts stratospheric temperature and ozoneLargest additional ozone depletion is estimated to occur in Antarctic spring 2023. The ozone response may not be detectable in observationsThe impacts are projected to gradually diminish after 2024 as the excess water vapor is removed from the stratosphere [ABSTRACT FROM AUTHOR]

We present a chemistry-climate model with a tagged stratospheric nitrous oxide (N2O) tracer that predicts distinct seasonal cycles in tropospheric N2O caused by descent of N2O-depleted stratospheric air in polar regions. We identify similar phenomena in recently available aircraft profiles from global campaigns and routine monitoring. Long-term atmospheric measurements from the National Oceanic Atmospheric Administration (NOAA) global surface monitoring network provide additional support for a significant impact on surface N2O originating from the stratosphere. In the northern hemisphere, the NOAA surface N2O atmospheric growth rate anomaly is negatively correlated with the previous winter's polar lower stratospheric temperature. This negative correlation is consistent with increased (decreased) transport in years with a strong weak) Brewer Dobson circulation of warm, N2O-depleted air from the middle and upper stratosphere into the lower stratosphere, with subsequent cross-tropopause transport of the N2O-depleted air into the troposphere. In the southern hemisphere, polar lower stratospheric temperature is correlated to monthly summertime anomalies in tropospheric N2O as it descends into its seasonal minimum, a result that is supported by aircraft data as well as the chemistry-climate model. However, the N2O atmospheric growth rate anomaly in the southern hemisphere is better correlated to the stratospheric quasibiennial oscillation (QBO) index, as well as the El Niño Southern Oscillation index, than to polar lower stratospheric temperature. These hemispheric differences in the factors influencing the N2O atmospheric growth rate are consistent with known atmospheric dynamics and the complex interaction of the QBO with the Brewer Dobson circulation. [ABSTRACT FROM AUTHOR]

We present a chemistry-climate model with a tagged stratospheric nitrous oxide (N2O) tracer that predicts distinct seasonal cycles in tropospheric N2O caused by descent of N2O-depleted stratospheric air in polar regions. We identify similar phenomena in recently available aircraft profiles from global campaigns and routine monitoring. Long-term atmospheric measurements from the National Oceanic Atmospheric Administration (NOAA) global surface monitoring network provide additional support for a significant impact on surface N2O originating from the stratosphere. In the northern hemisphere, the NOAA surface N2O atmospheric growth rate anomaly is negatively correlated with the previous winter's polar lower stratospheric temperature. This negative correlation is consistent with increased (decreased) transport in years with a strong (weak) Brewer Dobson circulation of warm, N2O-depleted air from the middle and upper stratosphere into the lower stratosphere, with subsequent cross-tropopause transport of the N2O-depleted air into the troposphere. In the southern hemisphere, polar lower stratospheric temperature is correlated to monthly summertime anomalies in tropospheric N2O as it descends into its seasonal minimum, a result that is supported by aircraft data as well as the chemistry-climate model. However, the N2O atmospheric growth rate anomaly in the southern hemisphere is better correlated to the stratospheric quasi-biennial oscillation (QBO) index, as well as the El Niño Southern Oscillation index, than to polar lower stratospheric temperature. These hemispheric differences in the factors influencing the N2O atmospheric growth rate are consistent with known atmospheric dynamics and the complex interaction of the QBO with the Brewer Dobson circulation. [ABSTRACT FROM AUTHOR]

Sensitivity to the strong coupling α S (M Z 2) is investigated using existing Deep Inelastic Scattering data from HERA in combination with projected future measurements from the Electron Ion Collider (EIC) in a next-to-next-to-leading order QCD analysis. A potentially world-leading level of precision is achievable when combining simulated inclusive neutral current EIC data with inclusive charged and neutral current measurements from HERA, with or without the addition of HERA inclusive jet and dijet data. The result can be obtained with substantially less than one year of projected EIC data at the lower end of the EIC centre-of-mass energy range. Some questions remain over the magnitude of uncertainties due to missing higher orders in the theoretical framework. [ABSTRACT FROM AUTHOR]

The impacts of stratospheric ozone recovery on Southern Ocean surface and interior temperature, heat content, heat uptake, and heat transport are investigated by contrasting two ensemble chemistry‐climate model simulations in 2005–2099: one with fixed ozone depleting substances (ODSs) and another with decreasing ODSs. In our simulations ozone recovery significantly affects Southern Ocean temperature, with large latitudinal and vertical variations. Ozone recovery causes a dipole change of the full‐depth ocean heat content (OHC) with an increase south of 60°S and a decrease between 45°S and 60°S. Integrated over latitudes south of 40°S, OHC decreases in response to ozone recovery. This ocean heat loss is shown to be driven by weakened poleward ocean heat transport (OHT) across 40°S, which is partly canceled by enhanced heat uptake. The weakening of poleward OHT into the Southern Ocean is caused by the ozone‐induced equatorward shift of the meridional overturning circulation. Plain Language Summary: With the phaseout of ozone depleting substances as controlled under the Montreal Protocol and its amendments, the stratospheric ozone layer is projected to recover to the pre‐ozone hole levels in this century. Stratospheric ozone recovery can influence temperature and circulation in the atmosphere and ocean. Here we study how stratospheric ozone recovery affects Southern Ocean temperature and heat content using a coupled atmosphere‐ocean‐chemistry model. The strong surface westerlies over the Southern Ocean play a crucial role in ocean circulation and climate. We find that ozone recovery influences Southern Ocean through its impact on the surface westerlies. Our model results show that ozone recovery causes a weakening and equatorward shift of the strong westerlies over the Southern Ocean. As a result, the ocean circulation in the Southern Ocean weakens, leading to a weaker poleward heat transport from the lower latitude into the Southern Ocean. A weaker heat transport results in Southern Ocean cooling and a decrease of the Southern OHC. Key Points: The decrease of ozone depleting substances in the 21st century causes a decrease of the Southern Ocean heatThe ozone‐induced Southern Ocean heat decrease is driven by weakened poleward ocean heat transport (OHT)The weakened poleward OHT is driven by the equatorward shift of the surface winds and meridional overturning circulation [ABSTRACT FROM AUTHOR]

The interaction of stratospheric chemistry with a changing climate from an abrupt CO2 quadrupling is assessed using the coupled atmosphere–ocean Goddard Earth Observing System Chemistry-Climate Model (GEOSCCM). Two abrupt 4 × CO2 experiments were performed, one with interactive stratospheric chemistry and the other with a prescribed stratospheric chemistry that does not simulate stratospheric ozone response to 4 × CO2. The interactive and prescribed chemistry experiments simulate similar global mean surface temperature change. Nevertheless, interactive chemistry is critical to capture the Southern Hemisphere tropospheric midlatitude jet response to 4 × CO2. When stratospheric ozone response to 4 × CO2 is neglected, GEOSCCM overestimates Southern Hemisphere tropospheric circulation change. This stratospheric chemistry-induced climate impact has large seasonal variability. During the austral spring season September–October–November (SON), prescribed chemistry yields a stronger poleward shift and intensification of the Southern Hemisphere midlatitude tropospheric jet, surface wind stress, and the Southern Ocean meridional overturning circulation than occurs with interactive chemistry. In other seasons interactive and prescribed chemistry have similar effects on the Southern Hemisphere circulation. The seasonality of stratospheric chemistry-induced climate impact is related to the seasonality of Antarctic lower stratospheric ozone response to 4 × CO2. In contrast to this stratospheric ozone response to 4 × CO2, stratospheric ozone recovery from decline of the ozone depleting substances has its largest impact on the Southern Hemisphere tropospheric circulation in austral summer (December–January–February), but no effects in SON. It is found that the different seasonality for these two stratospheric ozone layer change scenarios is related to the different seasonality of tropopause meridional temperature gradient response. [ABSTRACT FROM AUTHOR]

In this paper, we present a method for solving the localisation of a ground lidar using overhead imagery only. Public overhead imagery such as Google satellite images are readily available resources. They can be used as the map proxy for robot localisation, relaxing the requirement for a prior traversal for mapping as in traditional approaches. While prior approaches have focused on the metric localisation between range sensors and overhead imagery, our method is the first to learn both place recognition and metric localisation of a ground lidar using overhead imagery, and also outperforms prior methods on metric localisation with large initial pose offsets. To bridge the drastic domain gap between lidar data and overhead imagery, our method learns to transform an overhead image into a collection of 2D points, emulating the resulting point-cloud scanned by a lidar sensor situated near the centre of the overhead image. After both modalities are expressed as point sets, point-based machine learning methods for localisation are applied. [ABSTRACT FROM AUTHOR]

The quasi-biennial oscillation (QBO) was unexpectedly disrupted for only the second time in the historical record during the 2019/20 boreal winter. As the dominant mode of atmospheric variability in the tropical stratosphere, and a significant source of seasonal predictability globally, understanding the drivers behind this unusual behaviour is very important. Here, novel data from Aeolus, the first Doppler wind lidar in space, is used to observe the 2019/20 QBO disruption. Aeolus is the first satellite able to observe winds at high resolution on a global scale, and is therefore a uniquely capable platform for studying the evolution of the disruption and the broader circulation changes triggered by it. This study therefore contains the first direct wind observations of the QBO from space, and exploits measurements from a special Aeolus scanning mode, implemented to observe this disruption as it happened. Aeolus observes easterly winds of up to 20 ms-1 in the core of the disruption jet during July 2020. By co-locating with radiosonde measurements from Singapore and ERA5 reanalysis, like-for-like comparisons of the observed wind structures in the tropical stratosphere are produced, showing equatorial Kelvin wave activity and key parts of the Walker Circulation during the disruption period. The onset of the disruption easterly jet occurs 5 days earlier in Aeolus observations compared with the reanalysis. This analysis highlights how Aeolus and future Doppler wind lidar satellites can deepen our understanding of the QBO, its disruptions, and the tropical upper-troposphere lower-stratosphere region more generally. [ABSTRACT FROM AUTHOR]

The quasi-biennial oscillation (QBO) was unexpectedly disrupted for only the second time in the historical record during the 2019/20 boreal winter. As the dominant mode of atmospheric variability in the tropical stratosphere, and a significant source of seasonal predictability globally, understanding the drivers behind this unusual behaviour is very important. Here, novel data from Aeolus, the first Doppler wind lidar in space, is used to observe the 2019/20 QBO disruption. Aeolus is the first satellite able to observe winds at high resolution on a global scale, and is therefore a uniquely capable platform for studying the evolution of the disruption and the broader circulation changes triggered by it. This study therefore contains the first direct wind observations of the QBO from space, and exploits measurements from a special Aeolus scanning mode, implemented to observe this disruption as it happened. Aeolus observes easterly winds of up to 20 ms−1 in the core of the disruption jet during July 2020. By co-locating with radiosonde measurements from Singapore and ERA5 reanalysis, like-for-like comparisons of the observed wind structures in the tropical stratosphere are produced, showing equatorial Kelvin wave activity and key parts of the Walker Circulation during the disruption period. The onset of the disruption easterly jet occurs 5 days earlier in Aeolus observations compared with the reanalysis. This analysis highlights how Aeolus and future Doppler wind lidar satellites can deepen our understanding of the QBO, its disruptions, and the tropical upper-troposphere lower-stratosphere region more generally. [ABSTRACT FROM AUTHOR]

Deep convection associated with tropical cyclones leads to stratosphere‐troposphere exchange (STE), which affects the upper‐tropospheric ozone concentrations in the vicinity of the cyclones. This study estimates the ozone enhancements over India due to the North Indian Ocean (NIO) cyclones‐driven STE. Indicators such as stratospheric fraction and potential vorticity calculated using the reanalysis data sets suggest that roughly 70% of the cyclones show anomalously high stratospheric intrusions. Aircraft observations over different locations across India also show elevated ozone concentrations in the mid‐to‐upper troposphere on cyclone days. Further, ozone and stratospheric ozone tracer concentrations from Goddard Earth Observing System‐Chemistry simulations and the Copernicus Atmosphere Monitoring Service reanalysis data sets show up to 40 ppb of excess upper tropospheric ozone over India, of which stratospheric ozone accounts for roughly 60%. Stratospheric intrusion due to the Bay of Bengal and the Arabian Sea cyclones affected the upper tropospheric ozone amounts over North and South India, respectively. The stratospheric ozone was observed to propagate downwards into the troposphere, often reaching ∼600 hPa and, in some cases, even the surface. Plain Language Summary: This study estimates the increase in the amount of ozone in the upper half of the lower atmosphere ("upper troposphere") during the North Indian Ocean (NIO) cyclones. Ozone in the upper atmosphere ("stratosphere") protects the Earth from harmful ultraviolet radiation but affects human and ecosystem health when present in the lower atmosphere ("troposphere"). Generally, the ozone in the lower atmosphere occurs due to chemical reactions of gases and sometimes due to the transport from the ozone‐rich upper atmosphere. However, there is a barrier between the upper and the lower atmospheres, also known as the tropopause. Using observations and atmospheric models, we study the penetration of ozone from the upper atmosphere to the lower atmosphere, during the NIO cyclones which disturb the separation barrier. We studied 20 cyclones and found that they disturb the barrier between the upper and the lower atmosphere significantly over India and a large amount of ozone moves between them, so much so that it almost doubles the ozone concentration in the upper half of the lower atmosphere. A warmer world in the future could lead to more cyclones which could increase ozone in the lower atmosphere. Key Points: Stratosphere‐troposphere exchange (STE) over India due to the North Indian Ocean cyclones is studied using reanalysis data and model outputEnhanced stratospheric airmass (∼20%) and ozone (∼40 ppb) were evident in the upper troposphere and lower stratosphereSTE due to the Bay of Bengal and Arabian Sea cyclones influence ozone amplification over northern and southern India, respectively [ABSTRACT FROM AUTHOR]

The Asian summer monsoon (ASM) as a chemical transport system is investigated using a suite of models in preparation for an airborne field campaign over the Western Pacific. Results show that the dynamical process of anticyclone eddy shedding in the upper troposphere rapidly transports convectively uplifted Asian boundary layer air masses to the upper troposphere and lower stratosphere over the Western Pacific. The models show that the transported air masses contain significantly enhanced aerosol loading and a complex chemical mixture of trace gases that are relevant to ozone chemistry. The chemical forecast models consistently predict the occurrence of the shedding events, but the predicted concentrations of transported trace gases and aerosols often differ between models. The airborne measurements to be obtained in the field campaign are expected to help reduce the model uncertainties. Furthermore, the large‐scale seasonal chemical structure of the monsoon system is obtained from modeled carbon monoxide, a tracer of the convective transport of pollutants, which provides a new perspective of the ASM circulation, complementing the dynamical characterization of the monsoon. Plain Language Summary: The Asian summer monsoon has been known as a weather system for centuries, but only in the recent decades has the system been recognized for its importance in atmospheric composition. Monsoon deep convection lofts near surface air to 15–17 km altitudes thus altering the chemical composition of the tropopause layer. The process also sends aerosols and chemically active trace gas species into the stratosphere where they affect climate through their impacts on ozone and aerosol radiative forcing. To understand the monsoon transport process and its impacts on climate system, a large airborne field campaign, the Asian summer monsoon Chemical and Climate Impact Project, was planned. This paper presents a set of results from precampaign model studies. These results serve as the hypotheses for the field investigation and provide guidance for its operational planning. Key Points: This model study is conducted in preparation for an airborne field campaign investigating the Asian monsoon transportResult shows that eastward eddy shedding of the anticyclone significantly alters upper tropospheric composition over the Western PacificCO seasonal distribution provides a chemical perspective of the monsoon system and sheds new light on monsoon dynamics and circulation [ABSTRACT FROM AUTHOR]

This paper is about acoustic event detection and sound source localisation in urban scenarios. Specifically, we are interested in detecting and localising horns and sirens of emergency vehicles. Urban scenarios, though, can be characterised by copious, unstructured and unpredictable traffic noise, which can severely compromise the performance and effectiveness of traditional filtering techniques. By analysing the spectrograms of incoming stereo signals as images, we can leverage image processing techniques and obtain a demonstrably robust system. Indeed, image processing methods, such as convolutional neural networks, which do not operate locally, offer interesting mechanisms for background foreground separation. When applied to spectrograms, those mechanisms allow using the entire context of the soundscape to discover and learn correlations both in the time and frequency domains, de facto implementing noise detection through semantic segmentation. In a multi-task learning scheme, together with signal denoising, we perform acoustic event classification to identify the nature of the alerting sound. Lastly, we use the denoised signals to localise the acoustic source on the ground plane, by regressing the direction of arrival of the sound. Our experimental evaluation shows an average classification rate of 94%, and a median absolute error on the localisation of 7.5° when operating on audio frames of 0.5 s, and of 2.5° when operating on frames of 2.5 s. The system offers excellent performance in particularly challenging scenarios, where the noise level is remarkably high. [ABSTRACT FROM AUTHOR]

Phil Jaggar - known in northern Nigeria as I Malam Bala i - was a leading Hausaist of his generation. In addition to his major focus on Hausa, Jaggar also conducted research on Guruntum, a small West Chadic language that was the mother tongue of Andrew Haruna, his PhD student at the time. Jaggar was not only interested in the Hausa language, he also had a serious interest in the history of Hausa studies. [Extracted from the article]

We provide the theory and the system needed to create large-scale dense reconstructions for mobile-robotics applications: this stands in contrast to the object-centric reconstructions dominant in the literature. Our BOR2G system fuses data from multiple sensor modalities (cameras, lidars, or both) and regularizes the resulting 3D model. We use a compressed 3D data structure, which allows us to operate over a large scale. In addition, because of the paucity of surface observations by the camera and lidar sensors, we regularize over both two (camera depth maps) and three dimensions (voxel grid) to provide a local contextual prior for the reconstruction. Our regularizer reduces the median error between 27% and 36% in 7.3 km of dense reconstructions with a median accuracy between 4 and 8 cm. Our pipeline does not end with regularization. We take the unusual step to apply a learned correction mechanism that takes the global context of the reconstruction and adjusts the constructed mesh, addressing errors that are pathological to the first-pass camera-derived reconstruction. We evaluate our system using the Stanford Burghers of Calais, Imperial College ICL-NUIM, Oxford Broad Street (released with this paper), and the KITTI datasets. These latter datasets see us operating at a combined scale and accuracy not seen in the literature. We provide statistics for the metric errors in all surfaces created compared with those measured with 3D lidar as ground truth. We demonstrate our system in practice by reconstructing the inside of the EUROfusion Joint European Torus (JET) fusion reactor, located at the Culham Centre for Fusion Energy (UK Atomic Energy Authority) in Oxfordshire. [ABSTRACT FROM AUTHOR]

This article provides an overview of the NASA Atmospheric Tomography (ATom) mission and a summary of selected scientific findings to date. ATom was an airborne measurements and modeling campaign aimed at characterizing the composition and chemistry of the troposphere over the most remote regions of the Pacific, Southern, Atlantic, and Arctic Oceans, and examining the impact of anthropogenic and natural emissions on a global scale. These remote regions dominate global chemical reactivity and are exceptionally important for global air quality and climate. ATom data provide the in situ measurements needed to understand the range of chemical species and their reactions, and to test satellite remote sensing observations and global models over large regions of the remote atmosphere. Lack of data in these regions, particularly over the oceans, has limited our understanding of how atmospheric composition is changing in response to shifting anthropogenic emissions and physical climate change. ATom was designed as a global-scale tomographic sampling mission with extensive geographic and seasonal coverage, tropospheric vertical profiling, and detailed speciation of reactive compounds and pollution tracers. ATom flew the NASA DC-8 research aircraft over four seasons to collect a comprehensive suite of measurements of gases, aerosols, and radical species from the remote troposphere and lower stratosphere on four global circuits from 2016 to 2018. Flights maintained near-continuous vertical profiling of 0.15–13-km altitudes on long meridional transects of the Pacific and Atlantic Ocean basins. Analysis and modeling of ATom data have led to the significant early findings highlighted here. [ABSTRACT FROM AUTHOR]

Building good 3D maps is a challenging and expensive task, which requires high-quality sensors and careful, time-consuming scanning. We seek to reduce the cost of building good reconstructions by correcting views of existing low-quality ones in a post-hoc fashion using learnt priors over surfaces and appearance. We train a convolutional neural network model to predict the difference in inverse-depth from varying viewpoints of two meshes — one of low-quality that we wish to correct, and one of high-quality that we use as a reference. Our full model runs at 11.3 Hz when aggregating four input views. In contrast to previous work, we pay attention to the problem of excessive smoothing in corrected meshes. We address this with a suitable network architecture, and introduce a loss-weighting mechanism that emphasizes edges in the prediction. Furthermore, smooth predictions result in geometrical inconsistencies. To deal with this issue, we present a loss function which penalizes re-projection differences that are not due to occlusions. Future applications of this work will incorporate semantic scene understanding in a multi-task learning setting. We explore the efficacy of the proposed system in terms of gross error correction and generalization capability by showing its performance in practice on a subset of the Kitti Odometry dataset, complete with a component-wise ablation study. We evaluate correctness and completeness measures of surface reconstruction across viewpoints and show that the proposed system is introspective in regions lacking sufficient high-quality supervision — indeed, models trained with geometric consistency loss create a lot more surface in areas that were not supervised, in one case filling in 67.97% or 8010 m2 of an unlabeled input region. Finally, we assess the practical applicability of our method at large-scale by experiments over the full scope of the Kitti Odometry dataset. Broadly, as a measure of effectiveness, our model reduces gross errors by 45.3–77.5%, up to five times more than previous work. We also assess the practical applicability of our method to 3D reconstruction at large scales and find that compared to the baseline our model shows better stability in correctness when improving completeness of surfaces, and is effective in reducing median total error by up to 21.8 cm. [ABSTRACT FROM AUTHOR]

Highly diastereoselective coordination of unsymmetrical cationic 2,2′-bipyridine ligands bearing a chiral amidinium substituent to [Re(CO)3Cl] and [Ir(PhPy)2]+ cores is reported. Binding strength and stereoselectivity have been correlated with the position of the amidinium group on the bipy. The 4-, 5- and 6-substituted ligands all produce C-[Re(CO)3(LH)Cl]X selectively, while only the 4-derivative gives preferred formation of Δ-[Ir(Phpy)2(4-LH)](BF4)2. [ABSTRACT FROM AUTHOR]

Traditional approaches to outdoor vehicle localization assume a reliable, prior map is available, typically built using the same sensor suite as the on-board sensors used during localization. This work makes a different assumption. It assumes that an overhead image of the workspace is available and utilizes that as a map for use for range-based sensor localization by a vehicle. Here, range-based sensors are radars and lidars. Our motivation is simple, off-the-shelf, publicly available overhead imagery such as Google satellite images can be a ubiquitous, cheap, and powerful tool for vehicle localization when a usable prior sensor map is unavailable, inconvenient, or expensive. The challenge to be addressed is that overhead images are clearly not directly comparable to data from ground range sensors because of their starkly different modalities. We present a learned metric localization method that not only handles the modality difference, but is also cheap to train, learning in a self-supervised fashion without requiring metrically accurate ground truth. By evaluating across multiple real-world datasets, we demonstrate the robustness and versatility of our method for various sensor configurations in cross-modality localization, achieving localization errors on-par with a prior supervised approach while requiring no pixel-wise aligned ground truth for supervision at training. We pay particular attention to the use of millimeter-wave radar, which, owing to its complex interaction with the scene and its immunity to weather and lighting conditions, makes for a compelling and valuable use case. [ABSTRACT FROM AUTHOR]

The 21 June 2019 eruption of the Raikoke volcano (Kuril Islands, Russia; 48 ∘ N, 153 ∘ E) produced significant amounts of volcanic aerosols (sulfate and ash) and sulfur dioxide (SO2) gas that penetrated into the lower stratosphere. The dispersed SO2 and sulfate aerosols in the stratosphere were still detectable by multiple satellite sensors for many months after the eruption. For this study of SO2 and aerosol clouds we use data obtained from two of the Ozone Mapping and Profiler Suite sensors on the Suomi National Polar-orbiting Partnership satellite: total column SO2 from the Nadir Mapper and aerosol extinction profiles from the Limb Profiler as well as other satellite data sets. We evaluated the limb viewing geometry effect (the "arch effect") in the retrieval of the LP standard aerosol extinction product at 674 nm. It was shown that the amount of SO2 decreases with a characteristic period of 8–18 d and the peak of stratospheric aerosol optical depth recorded at a wavelength of 674 nm lags the initial peak of SO2 mass by 1.5 months. Using satellite observations and a trajectory model, we examined the dynamics of an unusual atmospheric feature that was observed, a stratospheric coherent circular cloud of SO2 and aerosol from 18 July to 22 September 2019. [ABSTRACT FROM AUTHOR]

INTRODUCTION: Military aeromedical evaluations are common, but specialized neuropsychological norms for aviation personnel are sparse, resulting in a need to rely on norms from the general population. Little has been published regarding aviation subpopulations and how their neuropsychological profiles may differ from general population normative data. This study investigated neuropsychological test results of aeromedical service members to evaluate consistency with general population norms, and to delineate differences between aviation subpopulations. METHODS: A nalyses were conducted on demographic variables and test scores of military aviators (N = 26) and nonaviator crewmembers (N = 36) referred for evaluation due to a clinical problem requiring a waiver for flight status. Performance differences between subsamples were investigated with general linear modeling. Base rates for low scores were described. RESULTS: Mean test scores in both subsamples were 0 to 1 standard deviation (SD) above the general population's means, with the largest discrepancies being found on measures of visuospatial ability (crewmembers) and verbal learning (aviators). Modeling revealed a significant difference between aviators and crewmembers on Trail Making Test Part B, after accounting for education. Aviators produced fewer low scores than crewmembers, even when using education adjusted normative data. DISCUSSION: Results suggest the cognitive profile of aviators is uniquely strong in specific domains, with fewer low scores. The development of aviator-specific norms may enhance sensitivity to cognitive decrements in this population. Future studies might separately assess crewmember roles to further assess cognitive performance standards across specialties. [ABSTRACT FROM AUTHOR]

The control of the production of ozone-depleting substances through the Montreal Protocol means that the stratospheric ozone layer is recovering1 and that consequent increases in harmful surface ultraviolet radiation are being avoided2,3. The Montreal Protocol has co-benefits for climate change mitigation, because ozone-depleting substances are potent greenhouse gases4–7. The avoided ultraviolet radiation and climate change also have co-benefits for plants and their capacity to store carbon through photosynthesis8, but this has not previously been investigated. Here, using a modelling framework that couples ozone depletion, climate change, damage to plants by ultraviolet radiation and the carbon cycle, we explore the benefits of avoided increases in ultraviolet radiation and changes in climate on the terrestrial biosphere and its capacity as a carbon sink. Considering a range of strengths for the effect of ultraviolet radiation on plant growth8–12, we estimate that there could have been 325–690 billion tonnes less carbon held in plants and soils by the end of this century (2080–2099) without the Montreal Protocol (as compared to climate projections with controls on ozone-depleting substances). This change could have resulted in an additional 115–235 parts per million of atmospheric carbon dioxide, which might have led to additional warming of global-mean surface temperature by 0.50–1.0 degrees. Our findings suggest that the Montreal Protocol may also be helping to mitigate climate change through avoided decreases in the land carbon sink.Modelling suggests that the Montreal Protocol may be mitigating climate change by protecting the land carbon sink, as well as by protecting the ozone layer and reducing greenhouse gas emissions. [ABSTRACT FROM AUTHOR]

The quasi‐biennial oscillation (QBO) of tropical stratospheric winds was disrupted during the 2019/20 Northern Hemisphere winter. We show that this latest disruption to the regular QBO cycling was similar in many respects to that seen in 2016, but initiated by horizontal momentum transport from the Southern Hemisphere. The predictable signal associated with the QBO's quasi‐regular phase progression is lost during disruptions and the oscillation reemerges after a few months significantly shifted in phase from what would be expected if it had progressed uninterrupted. We infer from an increased wave‐momentum flux into equatorial latitudes seen in climate model projections that disruptions to the QBO are likely to become more common in future. Consequently, it is possible that in the future, the QBO could be a less reliable source of predictability on lead times extending out to several years than it currently is. Plain Language Summary: The quasi‐biennial oscillation (QBO) consists of a regular switching between eastward and westward winds in the tropical stratosphere. The oscillation has persisted at least since its discovery in the 1960s, over which time its period averages about 28 months with some variability from cycle to cycle. Recently, during the Northern Hemisphere winters of 2015/16 and 2019/20, remarkable departures from this regular behavior occurred that have no precedent in the observational record. Both the 2015/16 and 2019/20 QBO disruptions occurred when large horizontal fluxes of momentum intruded into the tropics from higher latitudes. Using climate model projections, we find these horizontal fluxes are likely to increase in future, suggesting an increased future likelihood of QBO disruptions and a concomitant loss in QBO predictability. Key Points: A second recent disruption of the quasi‐biennial oscillation (QBO) has occurredLarge momentum fluxes from the Southern Hemisphere made a substantial contribution to the 2019/20 disruptionIncreased equatorward momentum flux in climate model projections suggests QBO disruptions may become more likely in future [ABSTRACT FROM AUTHOR]

In the wake of the first murder of an Indian by two Pennsylvania colonists in 1722, the Delaware (Lenape), Shawnee, Conoy (Piscataway), and Conestoga (Susquehannock/Mingo) Indians engineered a confederated diplomatic and political identity to defend their homeland. They styled themselves the "Four Nations of Indians upon the Susquehanna" to counteract the "Covenant Chain" devised by the Iroquois and colonial governments. Anthropologists have identified "ethno-genesis" wherein peoples from multiple Indian cultures wracked by epidemics intertwined to form wholly new cultures and nations. This, however, is a story of "politico-genesis." These four nations retained their individual languages and governing structures while living in multinational or adjacent towns and joined together to present a single diplomatic voice to the English government and the Iroquois League who sought to control them. This was an early and significant attempt at political and diplomatic confederation that Indian peoples would employ in centuries to follow. [ABSTRACT FROM AUTHOR]

This study offers an overview of the low-frequency (i.e., monthly to seasonal) evolution, dynamics, predictability, and surface impacts of a rare Southern Hemisphere (SH) stratospheric warming that occurred in austral spring 2019. Between late August and mid-September 2019, the stratospheric circumpolar westerly jet weakened rapidly, and Antarctic stratospheric temperatures rose dramatically. The deceleration of the vortex at 10 hPa was as drastic as that of the first-ever-observed major sudden stratospheric warming in the SH during 2002, while the mean Antarctic warming over the course of spring 2019 broke the previous record of 2002 by ∼50% in the midstratosphere. This event was preceded by a poleward shift of the SH polar night jet in the uppermost stratosphere in early winter, which was then followed by record-strong planetary wave-1 activity propagating upward from the troposphere in August that acted to dramatically weaken the polar vortex throughout the depth of the stratosphere. The weakened vortex winds and elevated temperatures moved downward to the surface from mid-October to December, promoting a record strong swing of the southern annular mode (SAM) to its negative phase. This record-negative SAM appeared to be a primary driver of the extreme hot and dry conditions over subtropical eastern Australia that accompanied the severe wildfires that occurred in late spring 2019. State-of-the-art dynamical seasonal forecast systems skillfully predicted the significant vortex weakening of spring 2019 and subsequent development of negative SAM from as early as late July. [ABSTRACT FROM AUTHOR]

Trichlorofluoromethane (CFC‐11, CFCl3) is a major anthropogenic ozone‐depleting substance and greenhouse gas, and its production and consumption are controlled under the Montreal Protocol. However, recent studies show that CFC‐11 emissions increased during 2014–2017 relative to 2008–2012. In this study, we use a chemistry‐climate model to investigate the stratospheric impacts of potential CFC‐11 emissions continuing into the future. As a sensitivity test, we use a high CFC‐11 scenario in which the inferred 2013–2016 average emissions of 72.5 Gg/yr is sustained to year 2100. This increases equivalent effective stratospheric chlorine by 15% in 2100, relative to the WMO (2018) baseline scenario in which future emissions decay with a bank release rate of 6.4%/year. Consistent with recent studies, the resulting ozone response has a linear dependence on the accumulated CFC‐11 emissions, yielding global and Antarctic spring total ozone sensitivity per 1,000 Gg of −0.37 and −3.9 DU, respectively, averaged over 2017–2100. The deepened ozone hole reduces UV heating, causing a colder Antarctic lower stratosphere in spring/early summer. Through thermal wind balance, this accelerates the circumpolar jet which in turn alters planetary and gravity wave propagation through the Southern Hemisphere stratosphere, and modifies the Brewer‐Dobson circulation. Age of air in the high scenario is slightly younger than the baseline in the lower stratosphere globally during 2090–2099, with a maximum change of −0.1 years. Coupled atmosphere‐ocean model simulations show that the resulting greenhouse gas impact of CFC‐11 is small and not statistically significant throughout the troposphere and stratosphere. Key Points: Continuing trichlorofluoromethane (CFC‐11) emissions will cause additional future stratospheric ozone depletionLargest statistically significant ozone depletion occurs in the global and Antarctic spring total column, and global upper stratosphereAdditional ozone depletion due to continuing CFC‐11 emissions will cause small changes in stratospheric temperature and circulation [ABSTRACT FROM AUTHOR]

The June 21, 2019 eruption of the Raikoke volcano (Kuril Islands, Russia, 48°N, 153°E) produced significant amounts of volcanic aerosols (sulfate and ash) and sulfur dioxide (SO2) gas that penetrated into the lower stratosphere. The dispersed SO2 and sulfate aerosols in the stratosphere were still detectable by multiple satellite sensors for three months after the eruption. For this study of SO2 and aerosol clouds we use data obtained from two of the Ozone Mapping Profiler Suite (OMPS) sensors on the Suomi National Polar-orbiting Partnership (SNPP) satellite: total column SO2 from the Nadir Mapper (NM) and aerosol extinction profiles from the Limb Profiler (LP) as well as other satellite data sets. The LP standard aerosol extinction product at 674 nm has been re-processed with an adjustment correcting for limb viewing geometry effects. It was shown that the amount of SO2 decreases with a characteristic period of 8-18 days and the peak of sulfate aerosol recorded at a wavelength of 674 nm lags the initial peak of SO2 by 1.5 months. Using satellite observations and a trajectory model, we examined the dynamics of unusual atmospheric feature that was observed, a stratospheric coherent circular cloud (CCC) of SO2 and aerosol from July 18 to September 22, 2019. [ABSTRACT FROM AUTHOR]

The Northern Hemisphere (NH) polar winter stratosphere of 2019/2020 featured an exceptionally strong and cold stratospheric polar vortex. Wave activity from the troposphere during December–February was unusually low, which allowed the polar vortex to remain relatively undisturbed. Several transient wave pulses nonetheless served to help create a reflective configuration of the stratospheric circulation by disturbing the vortex in the upper stratosphere. Subsequently, multiple downward wave coupling events took place, which aided in dynamically cooling and strengthening the polar vortex. The persistent strength of the stratospheric polar vortex was accompanied by an unprecedentedly positive phase of the Arctic Oscillation in the troposphere during January–March, which was consistent with large portions of observed surface temperature and precipitation anomalies during the season. Similarly, conditions within the strong polar vortex were ripe for allowing substantial ozone loss: The undisturbed vortex was a strong transport barrier, and temperatures were low enough to form polar stratospheric clouds for over 4 months into late March. Total column ozone amounts in the NH polar cap decreased and were the lowest ever observed in the February–April period. The unique confluence of conditions and multiple broken records makes the 2019/2020 winter and early spring a particularly extreme example of two‐way coupling between the troposphere and stratosphere. Plain Language Summary: Wintertime westerly winds in the polar stratosphere (from ∼15–50 km), known as the stratospheric polar vortex, were extraordinarily strong during the Northern Hemisphere winter of 2019/2020. The exceptional strength of the stratospheric polar vortex had consequences for winter and early spring weather near the surface and for stratospheric ozone depletion. Typically atmospheric waves generated in the troposphere spread outward and upward into the stratosphere where they can disturb and weaken the polar vortex, but tropospheric wave activity was unusually weak during the 2019/2020 winter. In addition, an unusual configuration of the stratospheric polar vortex developed that reflected waves traveling upward from the troposphere back downward. These unique conditions allowed the vortex to remain strong and cold for several months. During January–March 2020, the strong stratospheric polar vortex was closely linked to a near‐surface circulation pattern that resembles the positive phase of the so‐called "Arctic Oscillation" (AO). This positive AO pattern was also of record strength and influenced the regional distributions of temperatures and precipitation during the late winter and early spring. Cold and stable conditions within the polar vortex also allowed strong ozone depletion to take place, leading to lower ozone levels than ever before seen above the Arctic in spring. Key Points: The Arctic stratospheric polar vortex during the 2019/2020 winter was the strongest and most persistently cold in over 40 yearsLow tropospheric planetary wave driving and a wave‐reflecting configuration of the stratosphere supported the strong and cold polar vortexSeasonal records in the Arctic Oscillation and stratospheric ozone loss were related to the strong polar vortex [ABSTRACT FROM AUTHOR]

The stratospheric water vapor feedbacks on climate for abrupt CO2 quadrupling are investigated with the coupled atmosphere–ocean Goddard Earth Observing System Chemistry-Climate model. A feedback suppression method is used to quantify the stratospheric water vapor climate feedback parameter and the impacts of stratospheric water vapor increases on temperature and circulation. It is found that increases in stratospheric water vapor change the model's net climate feedback parameter by 0.11 W m−2 K−1, contributing to 0.5 K, or 10%, of the global-mean surface warming under abrupt CO2 quadrupling. Stratospheric water vapor increases lead to significant impacts on stratospheric temperature and dynamics. The increases induce stratospheric dynamical changes that strongly modify stratospheric cooling patterns. About 30% of the acceleration of the stratospheric Brewer-Dobson circulation under 4 × CO2 is attributed to the stratospheric water vapor increases. In the troposphere, the stratospheric water vapor feedback plays a role in Arctic amplification and is responsible for 14% of the Arctic warming. It also affects tropospheric circulation, causing greater poleward shift of the northern hemisphere tropospheric midlatitude jet. [ABSTRACT FROM AUTHOR]

We report DFT calculations on potential intramolecular, enantioselective hydrogenation catalysts based around borenium-carbenes based on a camphor scaffold. Using the M06-2X meta-hybrid functional, we find frustrated Lewis pair (FLP) behavior with suitably chosen linkers that prevent association of Lewis bases with the borenium center. These intramolecular FLPs are predicted to be able to heterolytically dissociate H2. Barriers to dissociation and the endo/exoergic nature of the reaction can be tuned by the nature of the base and substituent on B. The reactivity of the hydrogenated FLP catalyst with olefin and carbonyl substrates is then explored: we predict concerted reactions for all substrates considered with relatively low barriers and large exoergic character. Hydrogenation of both faces of a prochiral substrate is also examined, indicating a small but significant variation in reaction barrier in favor of the Si-face, ascribed to stronger interactions with the aromatic π -system in the TS compared to the Re-face. Frustrated Lewis Pairs (FLPs) created by utilizing borenium-carbenes based on a camphor scaffolds may present themselves as possible chiral hydrogenation catalysts. M06-2X meta-hybrid functional has been used to provide an insight into the mechanism of hydrogenation of olefin and carbonyl substrates. Studies on a prochiral substrate (acetophenone) suggests promise as enantioselective catalysts. [ABSTRACT FROM AUTHOR]

The ability of alkali metal complexes featuring functionalized BINOL-derived ligands to catalyze ketone hydroboration reactions was explored. The reduced products were formed in excellent yields and with variable enantioselectivities dependent upon the nature of the ligand and the alkali metal cation. [ABSTRACT FROM AUTHOR]

Plug gaps to measure ozone-destroying chemicals and greenhouse gases and verify compliance with Paris and Montreal treaties. [ABSTRACT FROM AUTHOR]

Benjamin Franklin "retired" from printing in 1747 but retained ownership of his press and a close working relationship with his printer, and Pennsylvania Gazette Editor David Hall. From King George's War in 1747 through the French and Indian War, Assemblyman Franklin used his press and the Gazette to forward his political objective of militarizing the Quaker Colony. During the French and Indian War, the Gazette pioneered standards of accurate reporting relying on eyewitness accounts, multiple sourcing, and networks of information that other presses imitated. This reporting provides vivid detail of the Allegheny Indians' successful strategy of using terror to influence Pennsylvania to sue for peace on Indian terms in 1758. At the same time, Franklin, Hall, and the Gazette moved beyond the reporting of fact and sensationalized Indian violence—not to sell papers but to militarize the colony for self-defense with fortifications, an army, and scalp bounties. The Allegheny Indians and the Gazette's tactics both achieved their intended goals, but also carried the unintended consequence of the ethnic cleansing of Pennsylvania. [ABSTRACT FROM AUTHOR]