Concentrations and radiative forcing of anthropogenic aerosols from 1750 to 2014 simulated with the Oslo CTM3 and CEDS emission inventory

We document the ability of the new-generation Oslo chemistry-transport model, Oslo CTM3, to accurately simulate present-day aerosol distributions. The model is then used with the new Community Emission Data System (CEDS) historical emission inventory to provide updated time series of anthropogenic aerosol concentrations and consequent direct radiative forcing (RFari) from 1750 to 2014.Overall, Oslo CTM3 performs well compared with measurements of surface concentrations and remotely sensed aerosol optical depth. Concentrations are underestimated in Asia, but the higher emissions in CEDS than previous inventories result in improvements compared to observations. The treatment of black carbon (BC) scavenging in Oslo CTM3 gives better agreement with observed vertical BC profiles relative to the predecessor Oslo CTM2. However, Arctic wintertime BC concentrations remain underestimated, and a range of sensitivity tests indicate that better physical understanding of processes associated with atmospheric BC processing is required to simultaneously reproduce both the observed features. Uncertainties in model input data, resolution, and scavenging affect the distribution of all aerosols species, especially at high latitudes and altitudes. However, we find no evidence of consistently better model performance across all observables and regions in the sensitivity tests than in the baseline configuration.Using CEDS, we estimate a net RFari in 2014 relative to 1750 of −0.17&thinsp;W&thinsp;m−2, significantly weaker than the IPCC AR5 2011–1750 estimate. Differences are attributable to several factors, including stronger absorption by organic aerosol, updated parameterization of BC absorption, and reduced sulfate cooling. The trend towards a weaker RFari over recent years is more pronounced than in the IPCC AR5, illustrating the importance of capturing recent regional emission changes.</p

Mitigation of Non-CO2 Aviation’s Climate Impact by Changing Cruise Altitudes

Aviation is seeking for ways to reduce its climate impact caused by CO2 emissions and non-CO2 effects. Operational measures which change overall flight altitude have the potential to reduce climate impact of individual effects, comprising CO2 but in particular non-CO2 effects. We study the impact of changes of flight altitude, specifically aircraft flying 2000 feet higher and lower, with a set of global models comprising chemistry-transport, chemistry-climate and general circulation models integrating distinct aviation emission inventories representing such alternative flight altitudes, estimating changes in climate impact of aviation by quantifying radiative forcing and induced temperature change. We find in our sensitivity study that flying lower leads to a reduction of radiative forcing of non-CO2 effects together with slightly increased CO2 emissions and impacts, when cruise speed is not modified. Flying higher increases radiative forcing of non-CO2 effects by about 10%, together with a slight decrease of CO2 emissions and impacts. Overall, flying lower decreases aviation-induced temperature change by about 20%, as a decrease of non-CO2 impacts by about 30% dominates over slightly increasing CO2 impacts assuming a sustained emissions scenario. Those estimates are connected with a large but unquantified uncertainty. To improve the understanding of mechanisms controlling the aviation climate impact, we study the geographical distributions of aviation-induced modifications in the atmosphere, together with changes in global radiative forcing and suggest further efforts in order to reduce long standing uncertainties

The use of QBO, ENSO, and NAO perturbations in the evaluation of GOME-2 MetOp A total ozone measurements

In this work we present evidence that quasi-cyclical perturbations in total ozone (quasi-biennial oscillation – QBO, El Niño–Southern Oscillation – ENSO, and North Atlantic Oscillation – NAO) can be used as independent proxies in evaluating Global Ozone Monitoring Experiment (GOME) 2 aboard MetOp A (GOME-2A) satellite total ozone data, using ground-based (GB) measurements, other satellite data, and chemical transport model calculations. The analysis is performed in the frame of the validation strategy on longer time scales within the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) Satellite Application Facility on Atmospheric Composition Monitoring (AC SAF) project, covering the period 2007–2016. Comparison of GOME-2A total ozone with ground observations shows mean differences of about -0.7±1.4&thinsp;% in the tropics (0–30∘), about +0.1±2.1&thinsp;% in the mid-latitudes (30–60∘), and about +2.5±3.2&thinsp;% and 0.0±4.3&thinsp;% over the northern and southern high latitudes (60–80∘), respectively. In general, we find that GOME-2A total ozone data depict the QBO–ENSO–NAO natural fluctuations in concurrence with the co-located solar backscatter ultraviolet radiometer (SBUV), GOME-type Total Ozone Essential Climate Variable (GTO-ECV; composed of total ozone observations from GOME, SCIAMACHY – SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY, GOME-2A, and OMI – ozone monitoring instrument, combined into one homogeneous time series), and ground-based observations. Total ozone from GOME-2A is well correlated with the QBO (highest correlation in the tropics of +0.8) in agreement with SBUV, GTO-ECV, and GB data which also give the highest correlation in the tropics. The differences between deseazonalized GOME-2A and GB total ozone in the tropics are within ±1&thinsp;%. These differences were tested further as to their correlations with the QBO. The differences had practically no QBO signal, providing an independent test of the stability of the long-term variability of the satellite data. Correlations between GOME-2A total ozone and the Southern Oscillation Index (SOI) were studied over the tropical Pacific Ocean after removing seasonal, QBO, and solar-cycle-related variability. Correlations between ozone and the SOI are on the order of +0.5, consistent with SBUV and GB observations. Differences between GOME-2A and GB measurements at the station of Samoa (American Samoa; 14.25∘&thinsp;S, 170.6∘&thinsp;W) are within ±1.9&thinsp;%. We also studied the impact of the NAO on total ozone in the northern mid-latitudes in winter. We find very good agreement between GOME-2A and GB observations over Canada and Europe as to their NAO-related variability, with mean differences reaching the ±1&thinsp;% levels. The agreement and small differences which were found between the independently produced total ozone datasets as to the influence of the QBO, ENSO, and NAO show the importance of these climatological proxies as additional tool for monitoring the long-term stability of satellite–ground-truth biases.</p

Liver and lymph node metastases of prostate cancer visualized on post-therapy imaging after treatment with Re-188-HEDP

Ezziddin, Samer/0000-0003-4110-3375WOS: 000330930200014PubMed: 23727275

Influence of weather situation on non-CO₂ aviation climate effects: the REACT4C climate change functions

Emissions of aviation include CO2, H2O, NOx, sulfur oxides, and soot. Many studies have investigated the annual mean climate impact of aviation emissions. While CO2 has a long atmospheric residence time and is almost uniformly distributed in the atmosphere, non-CO2 gases and particles and their products have short atmospheric residence times and are heterogeneously distributed. The climate impact of non-CO2 aviation emissions is known to vary with different meteorological background situations. The aim of this study is to systematically investigate the influence of characteristic weather situations on aviation climate effects over the North Atlantic region, to identify the most sensitive areas, and to potentially detect systematic weather-related similarities. If aircraft were re-routed to avoid climate-sensitive regions, the overall aviation climate impact might be reduced. Hence, the sensitivity of the atmosphere to local emissions provides a basis for the assessment of weather-related, climate-optimized flight trajectory planning. To determine the climate change contribution of an individual emission as a function of location, time, and weather situation, the radiative impact of local emissions of NOx and H2O to changes in O3, CH4, H2O and contrail cirrus was computed by means of the ECHAM5/MESSy Atmospheric Chemistry model. From this, 4-dimensional climate change functions (CCFs) were derived. Typical weather situations in the North Atlantic region were considered for winter and summer. Weather-related differences in O3, CH4, H2O, and contrail cirrus CCFs were investigated. The following characteristics were identified: enhanced climate impact of contrail cirrus was detected for emissions in areas with large-scale lifting, whereas low climate impact of contrail cirrus was found in the area of the jet stream. Northwards of 60∘ N, contrails usually cause climate warming in winter, independent of the weather situation. NOx emissions cause a high positive climate impact if released in the area of the jet stream or in high-pressure ridges, which induces a south- and downward transport of the emitted species, whereas NOx emissions at, or transported towards, high latitudes cause low or even negative climate impact. Independent of the weather situation, total NOx effects show a minimum at ∼250 hPa, increasing towards higher and lower altitudes, with generally higher positive impact in summer than in winter. H2O emissions induce a high climate impact when released in regions with lower tropopause height, whereas low climate impact occurs for emissions in areas with higher tropopause height. H2O CCFs generally increase with height and are larger in winter than in summer. The CCFs of all individual species can be combined, facilitating the assessment of total climate impact of aircraft trajectories considering CO2 and spatially and temporally varying non-CO2 effects. Furthermore, they allow for the optimization of aircraft trajectories with reduced overall climate impact. This also facilitates a fair evaluation of trade-offs between individual species. In most regions, NOx and contrail cirrus dominate the sensitivity to local aviation emissions. The findings of this study recommend considering weather-related differences for flight trajectory optimization in favour of reducing total climate impact

Influence of the actual weather situation on non-CO2 aviation climate effects: The REACT4C Climate Change Functions

The influence of different weather situations on non-CO2 aviation climate impact is investigated. The aim is to identify systematic weather related sensitivities. If aircraft trajectories avoid the most sensitive areas, the overall climate impact might be reduced. An enhanced significance of the position of emission release is identified in relation to high pressure systems, in relation to the jet stream, in relation to polar night, and in relation to the altitude of the tropopause. The results of this study represent a comprehensive dataset for studies aiming at weather dependent flight trajectory optimization reducing total climate impact

Assessing the climate impact of formation flights

Emissions of aviation include CO2, H2O, NOx and particles. While CO2 has a long atmospheric residence time and is uniformly distributed in the atmosphere, non-CO2 gases, particles and their products have short atmospheric residence times and are heterogeneously distributed. Their climate effects depend on chemical and meteorological background conditions during emission, which vary with geographic location, altitude, time, local insolation, actual weather, etc. This spatial and temporal variability can be utilized for aviation climate impact mitigation by identifying aircraft trajectories which avoid climate-sensitive regions. To determine the climate change contribution of individual emissions as function of 3-dimensional position, time and weather situation, contributions of local emissions to changes in O3, CH4, H2O and contrail-cirrus were computed by means of the ECHAM5/MESSy Atmospheric Chemistry model and four-dimensional climate change functions (CCFs) were derived thereof. Typical weather situations in the North Atlantic region were considered for winter and summer. For all non-CO2 species included in the study, we found distinct weather related differences with respect to their climate impact. Depending on the species, we found enhanced significance of the position of emission release in relation to high pressure systems, in relation to the jet stream, in relation to polar night and in relation to the tropopause altitude. The dominating parameters were found to be contrail-cirrus and total NOx. The results of this study represent a comprehensive basis for weather dependent flight trajectory optimization studies. Furthermore it constitutes the groundwork for the development of more generally applicable algorithmic CCFs.Aircraft Noise and Climate Effect

Exploring return to work barriers through the lens of model of human occupation. The NOW WHAT project

The challenges of returning to work after sickness absence demands a wide conceptual understanding of what hinders the employee’s work participation. Thus, there is a need to know more about self-perceived barriers for Return to Work (RTW). This study aimed to investigate RTW barriers experienced by employees on long-term sick leave, through the lens of the Model of Human Occupation (MOHO). The study was a large-scale qualitative interview study (n = 85) using semi-structured telephone interviews. Eligible participants had received sick leave benefits for between 6 months and 1.5 years. The data were analysed with quantitative and qualitative content analysis. A deductive approach using the MOHO concepts guided the analysis process. The study generated 941 coded meaning units describing barriers for RTW, of which we were able to code 895 within the framework of MOHO. In the person-specific concepts, performance capacity barriers were most often described (n = 303), followed by volitional barriers (n = 165) and barriers related to habituation (n = 66). Barriers related to the environmental components amounted to 361. Barriers in the occupational environment was dominant (n = 214). Experienced barriers related to both environmental components and person-specific concepts. The habituational and volitional perspective on barriers can contribute to the identification and communication of performance capacity-related barriers not previously identified.</p