272 research outputs found
Advancing national greenhouse gas inventories for agriculture in developing countries : improving activity data, emission factors and software technology
Peer reviewedPublisher PD
Agricultural climate change mitigation : Carbon calculators as a guide for decision making
This is an Accepted Manuscript of an article published by Taylor & Francis Group in International Journal of Agricultural Sustainability on 9 November 2017, available online: https://doi.org/10.1080/14735903.2017.1398628. Under embargo. Embargo end date: 9 November 2018.The dairy industry is receiving considerable attention in relation to both its significant greenhouse gas (GHG) emissions, and it’s potential for reducing those emissions, contributing towards meeting national targets and driving the industry towards sustainable intensification. However, the extent to which improvements can be made is dependent on the decision making processes of individual producers, so there has been a proliferation of carbon accounting tools seeking to influence those processes. This paper evaluates the suitability of such tools for driving environmental change by influencing on-farm management decisions. Seven tools suitable for the European dairy industry were identified, their characteristics evaluated, and used to process data relating to six scenario farms, emulating process undertaken in real farm management situations. As a result of the range of approaches taken by the tools, there was limited agreement between them as to GHG emissions magnitude, and no consistent pattern as to which tools resulted in the highest/lowest results. Despite this it is argued, that as there was agreement as to the farm activities responsible for the greatest emissions, the more complex tools were still capable of performing a ‘decision support’ role, and guiding management decisions, whilst others could merely focus attention on key issues.Peer reviewe
Evaluating the effects of bilingual traffic signs on driver performance and safety
Variable Message Signs (VMS) can provide immediate and relevant information to road users and bilingual VMS can provide great flexibility in countries where a significant proportion of the population speak an alternative language to the majority. The study reported here evaluates the effect of various bilingual VMS configurations on driver behaviour and safety. The aim of the study was to determine whether or not the visual distraction associated with bilingual VMS signs of different configurations (length, complexity) impacted on driving performance. A driving simulator was used to allow full control over the scenarios, road environment and sign configuration and both longitudinal and lateral driver performance was assessed. Drivers were able to read one and two-line monolingual signs and two-line bilingual signs without disruption to their driving behaviour. However, drivers significantly reduced their speed in order to read four-line monolingual and four-line bilingual signs, accompanied by an increase in headway to the vehicle in front. This implies that drivers are possibly reading the irrelevant text on the bilingual sign and various methods for reducing this effect are discussed
The DIRTY Model. I. Monte Carlo Radiative Transfer Through Dust
We present the DIRTY radiative transfer model in this paper and a companion
paper. This model computes the polarized radiative transfer of photons from
arbitrary distributions of stars through arbitrary distributions of dust using
Monte Carlo techniques. The dust re-emission is done self-consistently with the
dust absorption and scattering and includes all three important emission paths:
equilibrium thermal emission, non-equilibrium thermal emission, and the
aromatic features emission. The algorithm used for the radiative transfer
allows for the efficient computation of the appearance of a model system as
seen from any viewing direction. We present a simple method for computing an
upper limit on the output quantity uncertainties for Monte Carlo radiative
transfer models which use the weighted photon approach.Comment: 8 pages, 3 figures, accepted to the Ap
Characterizing the impact of urban emissions on regional aerosol particles: airborne measurements during the MEGAPOLI experiment
The MEGAPOLI (Megacities: Emissions, urban, regional and Global
Atmospheric POLlution and climate effects, and Integrated tools for
assessment and mitigation) experiment took place in July 2009. The aim of this campaign
was to study the aging and reactions of aerosol and gas-phase emissions in
the city of Paris. Three ground-based measurement sites and several mobile
platforms including instrument equipped vehicles and the ATR-42 aircraft
were involved. We present here the variations in particle- and gas-phase
species over the city of Paris, using a combination of high-time resolution
measurements aboard the ATR-42 aircraft. Particle chemical composition was
measured using a compact time-of-flight aerosol mass spectrometer (C-ToF-AMS), giving detailed information on the non-refractory submicron
aerosol species. The mass concentration of black carbon (BC), measured by a
particle absorption soot photometer (PSAP), was used as a marker to identify
the urban pollution plume boundaries. Aerosol mass concentrations and
composition were affected by air-mass history, with air masses that spent
longest time over land having highest fractions of organic aerosol and
higher total mass concentrations. The Paris plume is mainly composed of
organic aerosol (OA), BC, and nitrate aerosol, as well as high
concentrations of anthropogenic gas-phase species such as toluene, benzene,
and NO<sub>x</sub>. Using BC and CO as tracers for air-mass dilution, we observe
the ratio of ΔOA / ΔBC and ΔOA / ΔCO increase
with increasing photochemical age (−log(NO<sub>x</sub> / NO<sub>y</sub>)). Plotting the
equivalent ratios of different organic aerosol species (LV-OOA, SV-OOA, and
HOA) illustrate that the increase in OA is a result of secondary organic
aerosol (SOA) formation. Within Paris the changes in the ΔOA / ΔCO are similar to those observed during other studies in London, Mexico
City, and in New England, USA. Using the measured SOA volatile organic compounds (VOCs) species together
with organic aerosol formation yields, we were able to predict ~50% of
the measured organics. These airborne measurements during the MEGAPOLI
experiment show that urban emissions contribute to the formation of OA and
have an impact on aerosol composition on a regional scale
In situ, satellite measurement and model evidence on the dominant regional contribution to fine particulate matter levels in the Paris megacity
International audiencePublished by Copernicus Publications on behalf of the European Geosciences Union. 9578 M. Beekmann et al.: Evidence for a dominant regional contribution to fine particulate matter levels Abstract. A detailed characterization of air quality in the megacity of Paris (France) during two 1-month intensive campaigns and from additional 1-year observations revealed that about 70 % of the urban background fine particulate matter (PM) is transported on average into the megacity from upwind regions. This dominant influence of regional sources was confirmed by in situ measurements during short intensive and longer-term campaigns, aerosol optical depth (AOD) measurements from ENVISAT, and modeling results from PMCAMx and CHIMERE chemistry transport models. While advection of sulfate is well documented for other megacities, there was surprisingly high contribution from long-range transport for both nitrate and organic aerosol. The origin of organic PM was investigated by comprehensive analysis of aerosol mass spectrometer (AMS), radio-carbon and tracer measurements during two intensive campaigns. Primary fossil fuel combustion emissions constituted less than 20 % in winter and 40 % in summer of carbonaceous fine PM, unexpectedly small for a megacity. Cooking activities and, during winter, residential wood burning are the major primary organic PM sources. This analysis suggests that the major part of secondary organic aerosol is of modern origin , i.e., from biogenic precursors and from wood burning. Black carbon concentrations are on the lower end of values encountered in megacities worldwide, but still represent an issue for air quality. These comparatively low air pollution levels are due to a combination of low emissions per inhabitant , flat terrain, and a meteorology that is in general not conducive to local pollution build-up. This revised picture of a megacity only being partially responsible for its own average and peak PM levels has important implications for air pollution regulation policies
Maïdo observatory: a new high-altitude station facility at Reunion Island (21° S, 55° E) for long-term atmospheric remote sensing and in situ measurements
Since the nineties, atmospheric measurement systems have been deployed at Reunion Island, mainly for monitoring the atmospheric composition in the framework of NDSC/NDACC (Network for the Detection of <i>Stratospheric</i> Change/Network for the Detection of Atmospheric Composition Change). The location of Reunion Island presents a great interest because there are very few multi-instrumented stations in the tropics and particularly in the southern hemisphere. In 2012, a new observatory was commissioned in Maïdo at 2200 m above sea level: it hosts various instruments for atmospheric measurements, including lidar systems, spectro-radiometers and in situ gas and aerosol measurements. <br><br> This new high-altitude Maïdo station provides an opportunity:<br> 1. to improve the performance of the optical instruments above the marine boundary layer, and to open new perspectives on upper troposphere and lower stratosphere studies;<br> 2. to develop in situ measurements of the atmospheric composition for climate change surveys, in a reference site in the tropical/subtropical region of the southern hemisphere;<br> 3. to offer trans-national access to host experiments or measurement campaigns for focused process studies
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