Download or read book Modeling Aircraft Contrails and Emission Plumes for Climate Impacts written by Alexander Dean Naiman and published by Stanford University. This book was released on 2011 with total page 201 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aircraft emissions lead to contrails and change cloud coverage in the upper troposphere/lower stratosphere, but their quantitative impact on climate is highly uncertain. As environmental policy turns toward regulating anthropogenic climate change components, it will be necessary to improve quantification of the climate impacts of aviation. Toward this end, we present two models of aircraft emissions. The first model is a large eddy simulation (LES) with three-dimensional, eddy-resolving flow physics and ice deposition/sublimation microphysics. Modeled ice properties, cloud optical depths, and contrail width growth rates are consistent with observational field studies. A series of sensitivity cases shows the effect of various parameters over twenty minutes of simulation time. The analysis focuses on properties such as contrail optical depth and cross-sectional width that are relevant to climate impacts. Vertical wind shear is found to have the strongest effect on these properties through the kinematic spreading of the contrail. In cases with no shear, optical depth is most sensitive to aircraft type and ambient humidity. One model parameter, the effective emission index of ice crystals, is also found to affect optical depth. A subset of the LES cases is run for two hours of simulation time to approach the scale of dynamical time steps modeled by global climate simulations. These cases use more realistic ice microphysics, including sedimentation, and forced ambient turbulence, both of which are processes that control contrail development at late times. The second model is a simple, low cost parameterization of aircraft plume dynamics, intended to be used as a subgrid plume model (SPM) within large scale atmospheric simulations. The SPM provides basic plume cross-section time advancement that has been used as a dilution model within a coupled global atmosphere-ocean climate simulation to study the effects of aviation on air quality and climate. Comparison to the twenty-minute and two-hour LES results demonstrates that the SPM captures important plume development characteristics under the effect of vertical shear and atmospheric turbulence.

Download or read book Modeling Aircraft Contrails and Emission Plumes for Climate Impacts written by Alexander Dean Naiman and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Aircraft emissions lead to contrails and change cloud coverage in the upper troposphere/lower stratosphere, but their quantitative impact on climate is highly uncertain. As environmental policy turns toward regulating anthropogenic climate change components, it will be necessary to improve quantification of the climate impacts of aviation. Toward this end, we present two models of aircraft emissions. The first model is a large eddy simulation (LES) with three-dimensional, eddy-resolving flow physics and ice deposition/sublimation microphysics. Modeled ice properties, cloud optical depths, and contrail width growth rates are consistent with observational field studies. A series of sensitivity cases shows the effect of various parameters over twenty minutes of simulation time. The analysis focuses on properties such as contrail optical depth and cross-sectional width that are relevant to climate impacts. Vertical wind shear is found to have the strongest effect on these properties through the kinematic spreading of the contrail. In cases with no shear, optical depth is most sensitive to aircraft type and ambient humidity. One model parameter, the effective emission index of ice crystals, is also found to affect optical depth. A subset of the LES cases is run for two hours of simulation time to approach the scale of dynamical time steps modeled by global climate simulations. These cases use more realistic ice microphysics, including sedimentation, and forced ambient turbulence, both of which are processes that control contrail development at late times. The second model is a simple, low cost parameterization of aircraft plume dynamics, intended to be used as a subgrid plume model (SPM) within large scale atmospheric simulations. The SPM provides basic plume cross-section time advancement that has been used as a dilution model within a coupled global atmosphere-ocean climate simulation to study the effects of aviation on air quality and climate. Comparison to the twenty-minute and two-hour LES results demonstrates that the SPM captures important plume development characteristics under the effect of vertical shear and atmospheric turbulence.

Download or read book Micro physical Modeling of Aircraft Exhaust Plumes and Condensation Trails written by Thibaud M. Fritz and published by . This book was released on 2018 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ability to quantitatively assess the environmental impacts of air transport operations is necessary to estimate their current and future impacts on the environment. Emissions from aircraft engines are a significant contributor to atmospheric NOx driving climate change, air quality impacts and other environmental concerns. To quantify these effects, global chemistry-transport models are frequently used. However, such models assume homogeneous and instant dilution into large-scale grid cells and therefore neglect micro-physical processes, such as contrail formation, occurring in aircraft wakes. This assumption leads to inaccurate estimates of NOy partitioning, and thus, an over-prediction of ozone production. To account for non-linear plume processes, a Lagrangian aircraft plume model has been implemented. It includes a unified tropospheric-stratospheric chemical mechanism that incorporates heterogeneous chemistry. Micro-physical processes are considered throughout the entire plume lifetime. The dynamics of the plume are solved simultaneously using an operator splitting method. The plume model is used to quantify how the in-plume chemical composition is affected in response to various environmental conditions and different engine and/or fuel characteristics. Results demonstrate that an instant dilution model overestimates ozone production and accelerates conversion of nitrogen oxides compared to the plume model. Sensitivities to the NOx emission index have been derived and the dependence of the plume treatment on the background atmosphere mixing ratios, pressure and latitude has been investigated for a future regional scale assessment of the aviation sector. The cumulative impact of successive flights has been estimated. Contrail micro-physical and chemical properties have been computed under different scenarios. This aircraft plume model has been extensively validated and enables an in-depth assessment of the impact of one or multiple flights on local atmospheric conditions.

Download or read book Quantifying and Reducing the Uncertainties in Global Contrail Radiative Forcing written by Akshat Agarwal (Scientist in aeronautics and astronautics) and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The number of BC particles emitted by an aircraft engine is required to estimate the number of crystals that form in a contrail. Decreasing the number of crystals that form by 80% could reduce the contrail RF by 50%. The first part of this thesis develops an approach to estimate the number of particles emitted by an engine. Using two complementary datasets, I relate smoke number measurements to the BC mass concentration, quantify losses in the measurement system, and connect mass emissions to particle number emissions. The method is applied to existing BC measurements achieving an R2 of 0.80 and 0.82, respectively. Global BC emissions for all operations in 2015 were estimated to be 2.0 Gg/year (95% CI = 1.7 - 2.3) and 2.42 × 1026 particles/year (95% CI = 1.58 - 3.81 × 1026).

Download or read book Aviation and the Global Atmosphere written by Joyce E. Penner and published by Cambridge University Press. This book was released on 1999-06-28 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Intergovernmental Panel on Climate Change Special Report is the most comprehensive assessment available on the effects of aviation on the global atmosphere. The report considers all the gases and particles emitted by aircraft that modify the chemical properties of the atmosphere, leading to changes in radiative properties and climate change, and modification of the ozone layer, leading to changes in ultraviolet radiation reaching the Earth. This volume provides accurate, unbiased, policy-relevant information and is designed to serve the aviation industry and the expert and policymaking communities.

Download or read book A Review of NASA s Atmospheric Effects of Stratospheric Aircraft Project written by National Research Council and published by National Academies Press. This book was released on 1999-10-05 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: The NRC Panel on the Atmospheric Effects of Aviation (PAEAN) was established to provide guidance to NASA's Atmospheric Effects of Aviation Program (AEAP) by evaluating the appropriateness of the program's research plan, appraising the project-sponsored results relative to the current state of scientific knowledge, identifying key scientific uncertainties, and suggesting research activities likely to reduce those uncertainties. Over the last few years, the panel has written periodic reviews of both the subsonic aviation (Subsonic Assessment-SASS) and the supersonic aviation (Atmospheric Effects of Stratospheric Aircraft-AESA) components of AEAP, including: An Interim Review of the Subsonic Assessment Project (1997); An Interim Assessment of AEAP's Emissions Characterization and Near-Field Interactions Elements (1997); An Interim Review of the AESA Project: Science and Progress (1998); Atmospheric Effects of Aviation: A Review of NASA's Subsonic Assessment Project (1998). This report constitutes the final review of AESA and will be the last report written by this panel. The primary audience for these reports is the program managers and scientists affiliated with AEAP, although in some cases the topics discussed are of interest to a wider audience.

Download or read book Constraining Climate Impact Uncertainties from Future Aviation written by Inés Sanz-Morère and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Environmental impacts from the aviation sector are in continuous growth. The total sector contribution to anthropogenic climate forcing is approximately 3.5%, representing up to 9% of US greenhouse gas emissions from transportation in 2018. Despite the COVID-19 crisis, it is also expected to grow at a global rate of approximately 4% per year in the next 20 years, and a full sector recovery is expected by 2024. The total impacts of aviation emissions on the climate, however, are still uncertain. This is due to factors including (i) the uncertainty regarding the radiative effects of short- and long-term climate forcers; (ii) the difficulty of validating modeling tools e.g. contrail formation and persistence or stratospheric chemical response to emissions; and (iii) the growing interest in new air transportation technologies such as unmanned aerial vehicles, supersonic aviation, or hydrogen and alternative fuels. These factors together require a persistent effort to improve the available tools assessing aviation environmental footprint. The objective of this thesis is to provide additional insights into aviation climate impacts, by improving current modeling capabilities. Specially, I aim to resolve elements that will be of increasing interest as the sector evolves. The work is divided into two parts. The first part focuses on improving climate impact estimates from contrails, ice clouds which form behind aircraft. Those are estimated to cause approximately half of the total climate forcing from aviation. The second part focuses on developing modeling tools for assessing climate impacts from future commercially viable supersonic fleets, as multiple companies are currently designing projects of that type (Aerion, Boom, Spike Aerospace, NASA, Lockheed Martin, etc.). In the first part, I develop a new contrail radiative forcing model with a new parameterization to model exchanges of radiation when multiple cloud layers overlap occur. My parameterization also reduces current uncertainties related to uncertainties in contrail microphysical structure. I find that, assuming maximum possible overlap, cloud-contrail overlap in 2015 increased the net radiative forcing from contrails. This effect was greatest in the North-Atlantic corridor. For 2015, contrail-contrail overlap results in a 3% net reduction in the estimated radiative forcing. Finally, using "in situ" measurements to constrain contrail microphysical evolution pathways, I find that the global net radiative forcing due to contrails in 2015 is between 8.6 and 10.7 mW/m2. Relative to the mid-point, this uncertainty range is less than one quarter of that previously reported in the literature. In the second part, I estimate the sensitivity of the global supersonic market and its climate impacts to factors such as design choice, regulations and economic assumptions. For this, I develop a detailed supersonic aircraft design model providing robust information on cruise altitude, fuel burn and emissions variation with aircraft design choice. I also, in order to address overland restrictions, develop a high-resolution routing algorithm, capable of assessing optimal routing for multiple regulatory options. I obtain that, in the absence of flight path restrictions, a fleet of 130-870 supersonic aircraft can be feasible, operating up to 2.5% of the seat-kilometers in the global aviation market. This will result in a net increase of fuel burn from commercial passenger aviation of up to 7%. However, between 78% and 100% of the global unrestricted market potentials cannot be addressed when supersonic flight is restricted over land or over areas with a population density of more than 50 inhabitants per square kilometer. When evaluating environmental impacts, aircraft design choice can change the sign of supersonic aviation impact on non-CO2 aviation climate forcing. In general, implementing supersonic aviation results in a global warming effect. However, if reducing fleet average NOx emission index by 58%, through an increase in fuel burn of 7%, climate forcing can change from positive (increase) to negative (reduction). Designs aiming to address high-value demand, at the upper bound of supersonic speeds (cruise Mach number = 2.2), are the most environmentally harmful because of their higher cruise altitude and fuel burn. While based on my results, we shouldn't expect any significant viable market from them, a 10% fleet substitution would be responsible of a doubling in global non-CO2 radiative forcing impact.

Download or read book Climate Change and Aviation written by Stefan Gössling and published by Earthscan. This book was released on 2009 with total page 409 pages. Available in PDF, EPUB and Kindle. Book excerpt: First Published in 2009. Routledge is an imprint of Taylor & Francis, an informa company.

Download or read book Aviation and the Global Atmospheric Environment written by and published by . This book was released on 2004 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Based essentially on the Special Report on Aviation and Global Atmosphere, this booklet summarises the authoritative assessments of the effects of aviation emissions on the environment."--Forward.

Download or read book Plume scale and Regional scale Modeling Studies of Uncertainties Associated with Calculated Impacts of Aircraft Emissions on Upper Tropospheric O3 written by Fujung Tsai and published by . This book was released on 1999 with total page 191 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Aircraft Design for Reduced Climate Impact written by Emily Dallara and published by Stanford University. This book was released on 2011 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aircraft affect global climate through emissions of greenhouse gases and their precursors and by altering cirrus cloudiness. Changes in operations and design of future aircraft may be necessary to meet goals for limiting climate change. One method for reducing climate impacts involves designing aircraft to fly at altitudes where the impacts of NOx emissions are less severe and persistent contrail formation is less likely. By considering these altitude effects and additionally applying climate mitigation technologies, impacts can be reduced by 45-70% with simultaneous savings in total operating costs. Uncertainty is assessed, demonstrating that relative climate impact savings can be expected despite large scientific uncertainties. Strategies for improving climate performance of existing aircraft are also explored, revealing potential climate impact savings of 20-40%, traded for a 2% increase in total operating costs and reduced maximum range.

Download or read book Plume to Global scale Atmospheric Impacts of Aviation Emissions written by Thibaud Matthieu Martin Fritz and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: High-altitude emissions from current subsonic aviation or from potentially future supersonic aircraft modify the total column ozone, thus leading to either increases in tropospheric ozone or a decrease in stratospheric ozone, with the latter causing larger UV flux at the ground. Both changes affect human health and, in this thesis, I identify a column ozone-neutral altitude for subsonic and supersonic aviation. Adjoint models of CTMs have been developed to quantify receptor-oriented sensitivities of environmental metrics (e.g. population-weighted ozone exposure) to emissions. Adjoint modeling overcomes the numerical cost of source-oriented sensitivity analysis, as performed by forward models. However, adjoint models of atmospheric chemistry have historically been limited to the troposphere. In this thesis, I build upon previous work and extend the GEOS-Chem Adjoint to further include stratospheric processes, and then validate the sensitivities with multi-year scenarios. I then present adjoint-derived sensitivities to identify column ozone-neutral altitudes for subsonic and supersonic aviation, based on their respective emission characteristics. I find that the 12 - 15 km altitude band is approximately column ozone-neutral for aviation emissions. Neglecting the effects of plume-scale processes introduces a positive bias in the column ozone-neutral altitude that varies between 0.3 up to 1 km.

Download or read book Evaluating Fuel climate Tradeoffs in Contrail Avoidance written by Jad A. Elmourad and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Contrails, the line-shaped clouds that can form behind airplanes, have been estimated to be a major contributor to aviation-induced climate change. Operational contrail avoidance via flight re-routing may be an effective and efficient mitigation approach due to the geometry of contrail-forming regions. Contrail avoidance strategies will result in fuel burn penalties and, consequently, additional climate warming from carbon dioxide emissions; therefore, the climate benefit from avoiding contrails must be evaluated against the carbon dioxide penalties. Prior work has estimated the fuel burn and climate tradeoffs associated with contrail avoidance by focusing on a small set of routes or weather conditions, targeting only specific regions of the world, focusing on minimizing contrail length without quantifying the contrail impact, limiting deviations to horizontal or fixed altitude changes, or not using a fuel-optimal baseline for comparison. In this work, we evaluated the fuel-climate tradeoffs on a large scale by considering global coverage of flights with a full-year simulation accounting for daily and seasonal variation in meteorological conditions. We applied full altitude optimization of flight trajectories, focusing mainly on two contrail avoidance strategies: avoiding only nighttime or avoiding all contrails. The net climate impact of these strategies was evaluated by simulating individual contrail plumes and their radiative forcing impact, comparing trajectories to a fuel-optimal baseline in order to properly isolate the additional fuel requirements of contrail avoidance. We found that nearly 100% of contrail length can be avoided using vertical re-routing exclusively for a fuel burn penalty of 1.3-1.4% on the flights that perform maximum contrail avoidance. However, since only a fraction of the flights need to perform contrail avoidance, the fuel burn penalty averaged over the entire fleet was found to be 0.5% to avoid all contrails and 0.16% to avoid just the nighttime ones. A 5% limit on the fuel burn penalty per flight reduced the avoided contrail length to 97%, whereas limiting the per-flight fuel burn penalty to the mean value of 1.4% limited the reduction in contrail length to 70%. Regarding the climate impact of contrail avoidance strategies, we found that on the flights that applied contrail avoidance, the net climate impact was reduced by 93% for the sample avoiding all contrails and 92% for the sample avoiding only nighttime contrails. We found that on flights that formed contrails the energy forcing of contrails was an order of magnitude larger than that of carbon dioxide for a time horizon of 100 years. In terms of the overall net climate impact across the fleet, i.e., including flights without contrail avoidance, we found that by avoiding all contrails on flights that form them, the entire fleet's net climate impact was reduced by 80%. On the other hand, by avoiding only nighttime contrails, the entire fleet's net climate impact was reduced by 28%. Therefore, it is best to avoid all contrails unless avoidance decisions can be made on a per-contrail basis. The flight-by-flight distribution and the seasonal variation of the fuel-climate tradeoffs were also analyzed.

Download or read book The Impact from Emitted NOx and VOC in an Aircraft Plume written by Karin Pleijel and published by . This book was released on 1998 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Federal Aviation Administration s R D Budget Priorities for Fiscal Year 2008 written by United States. Congress. House. Committee on Science and Technology (2007). Subcommittee on Space and Aeronautics and published by . This book was released on 2007 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book For Greener Skies written by National Research Council and published by National Academies Press. This book was released on 2002-05-24 with total page 71 pages. Available in PDF, EPUB and Kindle. Book excerpt: Each new generation of commercial aircraft produces less noise and fewer emissions per passenger-kilometer (or ton-kilometer of cargo) than the previous generation. However, the demand for air transportation services grows so quickly that total aircraft noise and emissions continue to increase. Meanwhile, federal, state, and local noise and air quality standards in the United States and overseas have become more stringent. It is becoming more difficult to reconcile public demand for inexpensive, easily accessible air transportation services with concurrent desires to reduce noise, improve local air quality, and protect the global environment against climate change and depletion of stratospheric ozone. This situation calls for federal leadership and strong action from industry and government. U.S. government, industry, and universities conduct research and develop technology that could help reduce aircraft noise and emissions-but only if the results are used to improve operational systems or standards. For example, the (now terminated) Advanced Subsonic Technology Program of the National Aeronautics and Space Administration (NASA) generally brought new technology only to the point where a system, subsystem model, or prototype was demonstrated or could be validated in a relevant environment. Completing the maturation process-by fielding affordable, proven, commercially available systems for installation on new or modified aircraft-was left to industry and generally took place only if industry had an economic or regulatory incentive to make the necessary investment. In response to this situation, the Federal Aviation Administration, NASA, and the Environmental Protection Agency, asked the Aeronautics and Space Engineering Board of the National Research Council to recommend research strategies and approaches that would further efforts to mitigate the environmental effects (i.e., noise and emissions) of aviation. The statement of task required the Committee on Aeronautics Research and Technology for Environmental Compatibility to assess whether existing research policies and programs are likely to foster the technological improvements needed to ensure that environmental constraints do not become a significant barrier to growth of the aviation sector.

Download or read book Green Aviation written by Ramesh Agarwal and published by John Wiley & Sons. This book was released on 2016-09-20 with total page 536 pages. Available in PDF, EPUB and Kindle. Book excerpt: Green Aviation is the first authoritative overview of both engineering and operational measures to mitigate the environmental impact of aviation. It addresses the current status of measures to reduce the environmental impact of air travel. The chapters cover such items as: Engineering and technology-related subjects (aerodynamics, engines, fuels, structures, etc.), Operations (air traffic management and infrastructure) Policy and regulatory aspects regarding atmospheric and noise pollution. With contributions from leading experts, this volume is intended to be a valuable addition, and useful resource, for aerospace manufacturers and suppliers, governmental and industrial aerospace research establishments, airline and aviation industries, university engineering and science departments, and industry analysts, consultants, and researchers.