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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]

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 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]

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]

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]

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]

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]

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 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 article focuses on the usefulness of a firm's disclosure when there are multiple users with different agendas. This is complicated by the firm's control over disclosure content. The authors model the interactions among three hypothetical parties: an Incumbent, which represents a public firm, an Entrant, and a representative stockholder. They conclude that disclosure information is often deliberately misleading and advocate a greater role for the U.S. Securities and Exchange Commission to monitor the truthfulness of disclosures.

The author comments on the article "An Explanation for Accounting Income Smoothing," concerning the use of income smoothing to shift creditor beliefs that a business is a low-variance type of business. The author suggests that the ability to smooth is a function of company-specific characteristics such as the choice of a last in, first out or a first in, first out accounting choice. He raises concerns about the exogenous and ad hoc nature of restrictions placed on managerial, debt holder, and shareholder strategies. He suggests that if managers have the flexibility to determine how much income is reported, then problems arise in determining equilibrium strategies.

Abstract: A series of well‐defined copper(I) complexes bearing ring‐expanded N‐heterocyclic carbene (NHC) ligands has been applied to the azide–alkyne cycloaddition reaction. The obtained results notably showed that the six‐membered NHC ligands outperform well‐established five‐membered ones. [CuI(Mes‐6)] displayed a remarkable catalytic activity while respecting the strict criteria for click reactions. [ABSTRACT FROM AUTHOR]

Abstract: The relative impacts of greenhouse gas (GHG) increase and stratospheric ozone depletion on stratospheric mean age of air in the 1960–2010 period are quantified using the Goddard Earth Observing System Chemistry‐Climate Model. The experiment compares controlled simulations using a coupled atmosphere‐ocean version of the Goddard Earth Observing System Chemistry‐Climate Model, in which either GHGs or ozone depleting substances, or both factors evolve over time. The model results show that GHGs and ozone depleting substances have about equal contributions to the simulated mean age decrease, but GHG increases account for about two thirds of the enhanced strength of the lower stratospheric residual circulation. It is also found that both the acceleration of the diabatic circulation and the decrease of the mean age difference between downwelling and upwelling regions are mainly caused by GHG forcing. The results show that ozone depletion causes an increase in the mean age of air in the Antarctic summer lower stratosphere through two processes: (1) a seasonal delay in the Antarctic polar vortex breakup that inhibits young midlatitude air from mixing with the older air inside the vortex, and (2) enhanced Antarctic downwelling that brings older air from middle and upper stratosphere into the lower stratosphere. [ABSTRACT FROM AUTHOR]

An accurate estimate of global hydroxyl radical (OH) abundance is important for projections of air quality, climate, and stratospheric ozone recovery. As the atmospheric mixing ratios of methyl chloroform (CH3CCl3) (MCF), the commonly used OH reference gas, approaches zero, it is important to find alternative approaches to infer atmospheric OH abundance and variability. The lack of global bottom-up emission inventories is the primary obstacle in choosing a MCF alternative. We illustrate that global emissions of long-lived trace gases can be inferred from their observed mixing ratio differences between the Northern Hemisphere (NH) and Southern Hemisphere (SH), given realistic estimates of their NH-SH exchange time, the emission partitioning between the two hemispheres, and the NH versus SH OH abundance ratio. Using the observed long-term trend and emissions derived from the measured hemispheric gradient, the combination of HFC-32 (CH2F2), HFC-134a (CH2FCF3, HFC-152a (CH3CHF2), and HCFC-22 (CHClF2), instead of a single gas, will be useful as a MCF alternative to infer global and hemispheric OH abundance and trace gas lifetimes. The primary assumption on which this multispecies approach relies is that the OH lifetimes can be estimated by scaling the thermal reaction rates of a reference gas at 272 K on global and hemispheric scales. Thus, the derived hemispheric and global OH estimates are forced to reconcile the observed trends and gradient for all four compounds simultaneously. However, currently, observations of these gases from the surface networks do not provide more accurate OH abundance estimate than that from MCF. [ABSTRACT FROM AUTHOR]

This document describes the MOOS-IvP autonomy software for unmanned marine vehicles and its use in largescale ocean sensing systems. MOOS-IvP is composed of two open-source software projects funded by the Office of Naval Research. MOOS provides a core autonomy middleware capability, and the MOOS project additionally provides a set of ubiquitous infrastructure utilities. The IvP Helm is the primary component of an additional set of capabilities implemented to form a full marine autonomy suite known as MOOS-IvP. This software and architecture are platform and mission agnostic and allow for a scalable nesting of unmanned vehicle nodes to form large-scale, long-endurance ocean sensing systems composed of heterogeneous platform types with varying degrees of communications connectivity, bandwidth, and latency. [ABSTRACT FROM AUTHOR]

This paper is concerned with the in-field autonomous operation of unmanned marine vehicles in accordance with convention for safe and proper collision avoidance as prescribed by the Coast Guard Collision Regulations (COLREGS). These rules are written to train and guide safe human operation of marine vehicles and are heavily dependent on human common sense in determining rule applicability as well as rule execution, especially when multiple rules apply simultaneously. To capture, the flexibility exploited by humans, this work applies a novel method of multiobjective optimization, interval programming, in a behavior-based control framework for representing the navigation rules, as well as task behaviors, in a way that achieves simultaneous optimal satisfaction. We present experimental validation of this approach using multiple autonomous surface craft. This work represents the first in-field demonstration of multiobjective optimization applied to autonomous COLREGS-based marine vehicle navigation. © 2006 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

An 83-year-old woman presented with primary multifocal cutaneous B-cell lymphoma, presenting as discrete nodules on the right pinna and nail-bed of the left middle finger, diffuse swelling and erythema of several other nail-beds of the fingers and toes, with associated pincer nail deformity and rhinophyma. Because of the involvement of several sites not amenable to radiotherapy, she was treated with oral cyclical chlorambucil with good result. [ABSTRACT FROM AUTHOR]

A 55-year-old woman with severe, chronic, treatment-resistant ulcerating necrobiosis lipoidica of the shins was commenced on oral cyclosporin at a dose of 2.5 mg/kg/day. Improvement started within 1 week of commencing treatment, and the lesions healed completely over 8 months. Further ulceration occurred 3 months after discontinuing cyclosporin, with improvement on reintroduction of cyclosporin. There have been four previous case reports of healing of treatment-resistant ulcerating necrobiosis lipoidica with cyclosporin. [ABSTRACT FROM AUTHOR]