Micro-physical modeling of aircraft exhaust plumes and condensation Trails

Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2018.Cataloged from PDF version of thesis.Includes bibliographical references (pages 63-68).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.by Thibaud M. Fritz.S.M

Plume to global-scale atmospheric impacts of aviation emissions

Commercial aircraft combustion emissions impact the atmospheric composition, alter the Earth’s climate by accounting for ~4% of anthropogenic radiative forcing [72, 49] and affect surface air quality, causing an estimated ~16,000 premature mortalities per year [7, 28]. These environmental impacts are driven by chemical, microphysical and transport processes that span different magnitudes of temporal and spatial scales, from near-field inplume chemistry that evolve over minutes and distances of ~100 m to global-scale phenomena taking place at the continental scale. To evaluate aviation’s environmental impacts, all temporal and spatial scales need to be captured. In this thesis I develop and evaluate numerical models that span all modeling scales. First, I quantify the role of plume-scale processes in the atmospheric impact of aviation emissions. Previous literature has indicated that current global-scale modeling of aircraft emissions overestimates aviation-attributable ozone by instantly diluting emissions at a coarse resolution [86]. To estimate the magnitude of the ozone discrepancy, I use a recently-developed aircraft plume model to calculate the nonlinear chemical conversions that occur in aircraft plumes. I then propagate the plume-scale results to the global atmospheric impact through the chemistry transport model (CTM) GEOS-Chem by embedding a plume-scale parameterization. After accounting for plumescale processes, I find a ~5% downward correction in the simulated aviation-attributable ozone response. 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. Finally, previous assessments of the environmental impact of aviation emissions using global climate models have found that coupled chemistry-climate feedback could have a magnifying effect on the response to commercial aircraft emissions. However, the aviation-induced environmental impact estimated with climate models have not been found to be consistent with CTMs [15]. To identify the cause of this discrepancy between climate models and CTMs and to evaluate the relevance of climate feedbacks in the assessment of the environmental response of aviation emissions, I develop a newly-coupled model for climate-chemistry simulations, CESM2-GC, coupling the climate model CESM2 to the model of atmospheric chemistry GEOS-Chem. I then validate CESM2-GC against atmospheric observations and results from the GEOS-Chem CTM and the “native” chemistry option in CESM2, CAM-Chem. Using CESM2-GC, I perform ensemble runs to evaluate the magnitude of the coupled chemistry-climate effects when evaluating aviation’s ozone and particulate matter response. I find that the ensemble mean provides an aviation-attributable population-weighted ozone and particulate matter perturbations of 0.56 ppbv and 0.08 µg/m3 , consistent with previous estimates using the GEOS-Chem CTM. Besides an increase of ~70 mK in tropical and Northern mid latitudes tropospheric temperatures, I observe no statistically significant response in upper-tropospheric meteorology that could indicate that coupled chemistry-climate feedback magnifies the aviation-attributable environmental response.Ph.D

The role of plume-scale processes in long-term impacts of aircraft emissions

Emissions from aircraft engines contribute to atmospheric NOx, driving changes in both the climate and in surface air quality. Existing atmospheric models typically assume instant dilution of emissions into large-scale grid cells, neglecting non-linear, small-scale processes occurring in aircraft wakes. They also do not explicitly simulate the formation of ice crystals, which could drive local chemical processing. This assumption may lead to errors in estimates of aircraft-attributable ozone production, and in turn to biased estimates of aviation's current impacts on the atmosphere and the effect of future changes in emissions. This includes black carbon emissions, on which contrail ice forms. These emissions are expected to reduce as biofuel usage increases, but their chemical effects are not well captured by existing models. To address this problem, we develop a Lagrangian model that explicitly models the chemical and microphysical evolution of an aircraft plume. It includes a unified tropospheric-stratospheric chemical mechanism that incorporates heterogeneous chemistry on background and aircraft-induced aerosols. Microphysical processes are also simulated, including the formation, persistence, and chemical influence of contrails. The plume model is used to quantify how the longterm (24 h) atmospheric chemical response to an aircraft plume varies in response to different environmental conditions, engine characteristics, and fuel properties. We find that an instant-dilution model consistently overestimates ozone production compared to the plume model, up to a maximum error of ~ 200 % at cruise altitudes. Instant dilution of emissions also underestimates the fraction of remaining NOx, although the magnitude and sign of the error vary with season, altitude, and latitude. We also quantify how changes in black carbon emissions affect plume behavior. Our results suggest that a 50 % reduction in black carbon emissions, as may be possible through blending with certain biofuels, may lead to thinner, shorter-lived contrails. For the cases that we modeled, these contrails sublimate ∼ 5 % to 15 % sooner and are 10 % to 22 % optically thinner. The conversion of emitted NOx to HNO3 and N2O5 falls by 16 % and 33 %, respectively, resulting in chemical feedbacks that are not resolved by instant-dilution approaches. The persistent discrepancies between results from the instant-dilution approach and from the aircraft plume model demonstrate that a parameterization of effective emission indices should be incorporated into 3-D atmospheric chemistry transport models.NASA Glenn Research Center (Grant NNX14AT22A

Targeting cell-derived markers to improve the detection of invisible biological traces for the purpose of genetic-based criminal identification

Abstract At a crime scene, investigators are faced with a multitude of traces. Among them, biological traces are of primary interest for the rapid genetic-based identification of individuals. “Touch DNA” consists of invisible biological traces left by the simple contact of a person’s skin with objects. To date, these traces remain undetectable with the current methods available in the field. This study proposes a proof-of-concept for the original detection of touch DNA by targeting cell-derived fragments in addition to DNA. More specifically, adhesive-structure proteins (laminin, keratin) as well as carbohydrate patterns (mannose, galactose) have been detected with keratinocyte cells derived from a skin and fingermark touch-DNA model over two months in outdoor conditions. Better still, this combinatory detection strategy is compatible with DNA profiling. This proof-of-concept work paves the way for the optimization of tools that can detect touch DNA, which remains a real challenge in helping investigators and the delivery of justice

A mobile DNA laboratory for forensic science adapted to coronavirusSARS-CoV-2 diagnosis

International audienceThe Forensic Science Institute of the French "Gendarmerie Nationale" (IRCGN™) developed in 2015 an ISO 17025 certified mobile DNA laboratory for genetic analyses. This Mobil'DNA laboratory is a fully autonomous and adaptable mobile laboratory to perform genetic analyses in the context of crime scenes, terrorism attacks or disasters.To support the hospital taskforce in Paris during the peak of the COVID-19 epidemic, we adapted this mobile genetic laboratory to perform high-throughput molecular screening for coronavirus SARS-CoV-2 by real-time PCR. We describe the adaptation of this Mobil'DNA lab to assist in Coronavirus SARS-CoV-2 diagnosis

Impacts of a near-future supersonic aircraft fleet on atmospheric composition and climate

Supersonic aircraft will have environmental impacts distinct from those of subsonic aviation, and are once again being developed and bought. Assessments of supersonic aircraft emissions impacts over the last decade have focused on the ozone and climate impacts of nitrogen oxides and water vapor, but assumed zero-sulfur fuel, zero black carbon emissions, and neglect likely design constraints on near-future engine technology. We assess the impacts on atmospheric composition and non-CO2climate forcing of a near-future supersonic aircraft fleet with current-generation engine technology burning fossil-based kerosene fuel with current-day sulfur content. Using vehicle performance modeling, market demand projection and global atmospheric chemistry-transport modeling, we find that a supersonic fleet flying at Mach 1.6 and 15–17 km altitude, burning 19 Tg of fuel each year and emitting 170 Gg of NOxwould cause a 0.046% reduction in global column ozone. We estimate the radiative forcing (climate impact) from changes in atmospheric concentrations of ozone (2.9 mW m−2), water vapor (1.3 mW m−2), carbonaceous and inorganic aerosols (−6.6 mW m−2), and methane (−0.65 mW m−2), resulting in a net non-CO2, non-contrail forcing of −3.5 mW m−2and varying from −3.0 to −3.9 mW per m2per year to year. We also show that the use of zero-sulfur fuel would halve net ozone depletion but increases the net non-CO2non-contrail forcing to +2.8 mW m−2due to the loss of a cooling effect from sulfate aerosols. A smaller fleet of Mach 2.2 aircraft flying at 18–20 km and burning 14 Tg of fuel but emitting twice as much NOxper unit of fuel results in 17 times as much net ozone depletion. The net radiative forcing for this fleet is of uncertain sign, averaging −0.15 mW m−2but varying between −3.2 and +2.0 mW per m2per year to year. Our results show that assessments of near-future supersonic aviation must consider the effects of fuel sulfur and black carbon alongside emissions of water vapor, NOx, and CO2, and that the net environmental impacts will be a trade-off between competing environmental concerns

Identifying the ozone-neutral aircraft cruise altitude

Depletion of stratospheric ozone, and the associated increase in population exposure to UV radiation, is an environmental consequence of high-altitude, supersonic aviation. Assessments of the impacts of emissions from subsonic aircraft – which fly at lower altitudes – have instead shown that they produce a net increase, rather than decrease, in global net ozone, suggesting the existence of an intermediate “column ozone neutral” cruise altitude. Knowing this altitude and its variation with factors such as latitude, season, and fuel composition could provide a pathway towards reducing the environmental impacts of aviation, but would require a prohibitive number of atmospheric simulations. We instead use the newly developed GEOS-Chem tropospheric-stratospheric adjoint to identify the location of the column ozone-neutral aircraft cruise altitude as a function of these factors. We show that, although the mean ozone neutral altitude is at 13.5 km globally, this varies from 14.6 km to 12.5 km between the equator and 60°N. This altitude varies by less than a kilometer between seasons, but the net depletion resulting from flying at greater altitudes varies by a factor of two. We also find that eliminating fuel sulfur would result in a neutral altitude 0.5–1.0 km greater than when conventional jet fuel is burned. Our results imply that a low Mach number supersonic aircraft burning low-sulfur fuel (e.g. biofuels) may be able to achieve net zero global ozone change. However, for a fleet to achieve ozone neutrality will require careful consideration of the non-linear variation in sensitivity with altitude and latitude.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Aircraft Noise and Climate Effect

geoschem/geos-chem: GEOS-Chem 13.2.0

<p>Release date: 07 Sep 2021</p> <p>This is a minor version release featuring the following updates:</p> <ul> <li>CEDS v2 emissions</li> <li>Updated Yuan/BNU MODIS LAI</li> <li>Blowing snow emissions</li> <li>Luo et al 2020 wetdep (option)</li> <li>Trace metal simulation</li> <li>Several fixes for minor issues</li> </ul> <p>See the <a href="http://wiki.seas.harvard.edu/geos-chem/index.php/GEOS-Chem_13.2.0">GEOS-Chem 13.2.0</a> page for a complete list of updates.</p> What's Changed <ul> <li>Update to CEDS v2 emissions by @msulprizio in <a href="https://github.com/geoschem/geos-chem/pull/766">https://github.com/geoschem/geos-chem/pull/766</a></li> <li>Trace metals simulation -- brought up to GEOS-Chem 13 by @yantosca in <a href="https://github.com/geoschem/geos-chem/pull/769">https://github.com/geoschem/geos-chem/pull/769</a></li> <li>Add lon & lat bounds to GEOS-Chem Classic HISTORY output by @yantosca in <a href="https://github.com/geoschem/geos-chem/pull/774">https://github.com/geoschem/geos-chem/pull/774</a></li> <li>Implement Luo et al 2020 wet deposition algorithm (supersedes PR #522) by @yantosca in <a href="https://github.com/geoschem/geos-chem/pull/779">https://github.com/geoschem/geos-chem/pull/779</a></li> <li>Blowing snow from sea salt aerosol by @lizziel in <a href="https://github.com/geoschem/geos-chem/pull/777">https://github.com/geoschem/geos-chem/pull/777</a></li> </ul> <p><strong>Full Changelog</strong>: <a href="https://github.com/geoschem/geos-chem/compare/13.1.2...13.2.0">https://github.com/geoschem/geos-chem/compare/13.1.2...13.2.0</a></p&gt