558 research outputs found

    Field demonstration of simultaneous wind and temperaturemeasurements from 5to50 km with a Na double-edge magneto-optic filter in a multi-frequency Doppler lidar

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    We report the first (to our knowledge) field demonstration of simultaneous wind and temperature measurements with a Na double-edge magneto-optic filter implemented in the receiver of a three-frequency Na Doppler lidar. Reliable winds and temperatures were obtained in the altitude range of 10-45 km with 1 km resolution and 60 min integration under the conditions of 0.4 W lidar power and 75 cm telescope aperture. This edge filter with a multi-frequency lidar concept can be applied to other direct-detection Doppler lidars for profiling both wind and temperature simultaneously from the lower to the upper atmosphere

    Plastic ingestion is an underestimated cause of death for southern hemisphere albatrosses

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    Albatrosses are among the world’s most imperiled vertebrates, with 73% ofspecies threatenedwith extinction. Ingestion of plastic is awell-recognized threatamong threeNorth Pacific species, but lesser known in the southern hemisphere,where it is considered a minor threat. As plastic entering the ocean is increasingwhile albatross populations decline, the threat of ocean plastic to albatrosspopulations may be underestimated. We present case studies of 107 beach-castalbatrosses of twelve species, received by wildlife hospitals in Australia and NewZealand, and estimate plastic ingestion and mortality rates for albatrosses in thesouthern hemisphere. Ingested plastic was present in 5.6% of individuals, andthe cause of death in half of these cases. We estimate ingestion of plastic maycause 3.4–17.5% of nearshoremortalities and is worth consideration as a substantialthreat to albatross populations. We provide clinical findings and “checklist”methodologies for identifying potential cases of foreign-body gastrointestinalobstruction. We suggest practical policy responses, empowering decision makersto reduce albatross mortality from anthropogenic sources

    Overview of the Second Texas Air Quality Study (TexAQS II) and the Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS)

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    The Second Texas Air Quality Study (TexAQS II) was conducted in eastern Texas during 2005 and 2006. This 2-year study included an intensive field campaign, TexAQS 2006/Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS), conducted in August–October 2006. The results reported in this special journal section are based on observations collected on four aircraft, one research vessel, networks of ground-based air quality and meteorological (surface and radar wind profiler) sites in eastern Texas, a balloon-borne ozonesonde-radiosonde network (part of Intercontinental Transport Experiment Ozonesonde Network Study (IONS-06)), and satellites. This overview paper provides operational and logistical information for those platforms and sites, summarizes the principal findings and conclusions that have thus far been drawn from the results, and directs readers to appropriate papers for the full analysis. Two of these findings deserve particular emphasis. First, despite decreases in actual emissions of highly reactive volatile organic compounds (HRVOC) and some improvements in inventory estimates since the TexAQS 2000 study, the current Houston area emission inventories still underestimate HRVOC emissions by approximately 1 order of magnitude. Second, the background ozone in eastern Texas, which represents the minimum ozone concentration that is likely achievable through only local controls, can approach or exceed the current National Ambient Air Quality Standard of 75 ppbv for an 8-h average. These findings have broad implications for air quality control strategies in eastern Texas

    The Indianapolis Flux Experiment (INFLUX): A test-bed for developing urban greenhouse gas emission measurements

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    The objective of the Indianapolis Flux Experiment (INFLUX) is to develop, evaluate and improve methods for measuring greenhouse gas (GHG) emissions from cities. INFLUX’s scientific objectives are to quantify CO2 and CH4 emission rates at 1 km2 resolution with a 10% or better accuracy and precision, to determine whole-city emissions with similar skill, and to achieve high (weekly or finer) temporal resolution at both spatial resolutions. The experiment employs atmospheric GHG measurements from both towers and aircraft, atmospheric transport observations and models, and activity-based inventory products to quantify urban GHG emissions. Multiple, independent methods for estimating urban emissions are a central facet of our experimental design. INFLUX was initiated in 2010 and measurements and analyses are ongoing. To date we have quantified urban atmospheric GHG enhancements using aircraft and towers with measurements collected over multiple years, and have estimated whole-city CO2 and CH4 emissions using aircraft and tower GHG measurements, and inventory methods. Significant differences exist across methods; these differences have not yet been resolved; research to reduce uncertainties and reconcile these differences is underway. Sectorally- and spatially-resolved flux estimates, and detection of changes of fluxes over time, are also active research topics. Major challenges include developing methods for distinguishing anthropogenic from biogenic CO2 fluxes, improving our ability to interpret atmospheric GHG measurements close to urban GHG sources and across a broader range of atmospheric stability conditions, and quantifying uncertainties in inventory data products. INFLUX data and tools are intended to serve as an open resource and test bed for future investigations. Well-documented, public archival of data and methods is under development in support of this objective

    Assessing the optimized precision of the aircraft mass balance method for measurement of urban greenhouse gas emission rates through averaging

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    To effectively address climate change, aggressive mitigation policies need to be implemented to reduce greenhouse gas emissions. Anthropogenic carbon emissions are mostly generated from urban environments, where human activities are spatially concentrated. Improvements in uncertainty determinations and precision of measurement techniques are critical to permit accurate and precise tracking of emissions changes relative to the reduction targets. As part of the INFLUX project, we quantified carbon dioxide (CO2), carbon monoxide (CO) and methane (CH4) emission rates for the city of Indianapolis by averaging results from nine aircraft-based mass balance experiments performed in November-December 2014. Our goal was to assess the achievable precision of the aircraft-based mass balance method through averaging, assuming constant CO2, CH4 and CO emissions during a three-week field campaign in late fall. The averaging method leads to an emission rate of 14,600 mol/s for CO2, assumed to be largely fossil-derived for this period of the year, and 108 mol/s for CO. The relative standard error of the mean is 17% and 16%, for CO2 and CO, respectively, at the 95% confidence level (CL), i.e. a more than 2-fold improvement from the previous estimate of ~40% for single-flight measurements for Indianapolis. For CH4, the averaged emission rate is 67 mol/s, while the standard error of the mean at 95% CL is large, i.e. ±60%. Given the results for CO2 and CO for the same flight data, we conclude that this much larger scatter in the observed CH4 emission rate is most likely due to variability of CH4 emissions, suggesting that the assumption of constant daily emissions is not correct for CH4 sources. This work shows that repeated measurements using aircraft-based mass balance methods can yield sufficient precision of the mean to inform emissions reduction efforts by detecting changes over time in urban emissions

    From Providers to PHOs: an institutional analysis of nonprofit primary health care governance in New Zealand

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    Policy reforms to primary health care delivery in New Zealand required government-funded firms overseeing care delivery to be constituted as nonprofit entities with governance shared between consumer and producers. This paper examines the consumer and producer interests in the allocation of ownership and control of New Zealand firms delivering primary health care utilising theories of competition in the markets for ownership and control of firms. Consistent with pre-reform patterns of ownership and control provider interests appear to have exerted effective control over the formation and governance of the new entities in all but a few cases where community (consumer) control was already established. Their ability to do so is implied from the absence of a defined ownership stake via which the balance of governance control could shift as a consequence of changes to incentives facing the different stakeholding groups. It appears that the pre-existing patterns will prevail and further intervention will be required if policymakers are to achieve their underlying aims
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