@article{abrahamsonPredictiveModelDevelopment2016,
  title = {Predictive {{Model Development}} for {{Aviation Black Carbon Mass Emissions}} from {{Alternative}} and {{Conventional Fuels}} at {{Ground}} and {{Cruise}}},
  author = {Abrahamson, Joseph P. and Zelina, Joseph and Andac, M. Gurhan and Vander Wal, Randy L.},
  year = {2016},
  month = nov,
  journal = {Environmental Science \& Technology},
  volume = {50},
  number = {21},
  pages = {12048--12055},
  publisher = {{American Chemical Society}},
  issn = {0013-936X},
  doi = {10.1021/acs.est.6b03749},
  urldate = {2022-03-21},
  abstract = {The first order approximation (FOA3) currently employed to estimate BC mass emissions underpredicts BC emissions due to inaccuracies in measuring low smoke numbers (SNs) produced by modern high bypass ratio engines. The recently developed Formation and Oxidation (FOX) method removes the need for and hence uncertainty associated with (SNs), instead relying upon engine conditions in order to predict BC mass. Using the true engine operating conditions from proprietary engine cycle data an improved FOX (ImFOX) predictive relation is developed. Still, the current methods are not optimized to estimate cruise emissions nor account for the use of alternative jet fuels with reduced aromatic content. Here improved correlations are developed to predict engine conditions and BC mass emissions at ground and cruise altitude. This new ImFOX is paired with a newly developed hydrogen relation to predict emissions from alternative fuels and fuel blends. The ImFOX is designed for rich-quench-lean style combustor technologies employed predominately in the current aviation fleet.}
}

@article{brauerAirborneMeasurementsContrail2021,
  title = {Airborne {{Measurements}} of {{Contrail Ice Properties}}\textemdash{{Dependence}} on {{Temperature}} and {{Humidity}}},
  author = {Br{\"a}uer, T. and Voigt, C. and Sauer, D. and Kaufmann, S. and Hahn, V. and Scheibe, M. and Schlager, H. and Diskin, G. S. and Nowak, J. B. and DiGangi, J. P. and Huber, F. and Moore, R. H. and Anderson, B. E.},
  year = {2021},
  month = apr,
  journal = {Geophysical Research Letters},
  volume = {48},
  number = {8},
  issn = {0094-8276, 1944-8007},
  doi = {10.1029/2020GL092166},
  urldate = {2022-02-21},
  abstract = {The largest share in the climate impact of aviation results from contrail cirrus clouds. Here, the dependence of microphysical contrail ice properties and extinction on temperature and humidity is investigated. Contrail measurements were performed at various altitudes during the 2018 ECLIF II/ NDMAX campaign with the NASA DC-8 chasing the DLR A320. Ice number concentrations and contrail extinction coefficients are largest at altitudes near 9.5 km, typical for short- and medium-range air traffic. At higher altitudes near 11.5 km, low ambient water vapor concentrations lead to smaller contrail particle sizes and lower extinction coefficients. In addition, contrails were detected below 8.2 km near the Schmidt-Appleman contrail formation threshold temperature. Here, only a small fraction ({$<$}15\%) of the emitted soot particles were activated into ice. Our observations enhance the understanding of contrail formation near the formation threshold and give a glimpse on the altitude dependence of climate-relevant contrail properties.},
  langid = {english}
}

@article{bremEffectsFuelAromatic2015,
  title = {Effects of {{Fuel Aromatic Content}} on {{Nonvolatile Particulate Emissions}} of an {{In-Production Aircraft Gas Turbine}}},
  author = {Brem, Benjamin T. and Durdina, Lukas and Siegerist, Frithjof and Beyerle, Peter and Bruderer, Kevin and Rindlisbacher, Theo and {Rocci-Denis}, Sara and Andac, M. Gurhan and Zelina, Joseph and Penanhoat, Olivier and Wang, Jing},
  year = {2015},
  month = nov,
  journal = {Environmental Science \& Technology},
  volume = {49},
  number = {22},
  pages = {13149--13157},
  issn = {0013-936X, 1520-5851},
  doi = {10.1021/acs.est.5b04167},
  urldate = {2022-04-29},
  langid = {english}
}

@misc{CalculateDistanceBearing,
  title = {Calculate Distance and Bearing between Two {{Latitude}}/{{Longitude}} Points Using Haversine Formula in {{JavaScript}}},
  urldate = {2023-04-12},
  howpublished = {https://www.movable-type.co.uk/scripts/latlong.html}
}

@article{celikel2001forecasting,
  title = {Forecasting Civil Aviation Fuel Burn and Emissions in {{Europe}}},
  author = {Celikel, A and Jelinek, F},
  year = {2001},
  journal = {EUROCONTROL Experimental Centre}
}

@book{cumpstyJetPropulsion2015,
  title = {Jet {{Propulsion}}},
  author = {Cumpsty, Nicholas and Heyes, Andrew},
  year = {2015},
  month = jul,
  publisher = {{Cambridge University Press}},
  abstract = {This book is a self-contained introduction to the aerodynamic and thermodynamic design of modern civil and military jet engine design. Through two engine design projects for a large passenger and a new fighter aircraft, the text explains modern engine design. Individual sections cover aircraft requirements, aerodynamics, principles of gas turbines and jet engines, elementary compressible fluid mechanics, bypass ratio selection, scaling and dimensional analysis, turbine and compressor design and characteristics, design optimization, and off-design performance. The civil aircraft, which was the core of the Part 1 of earlier editions, has now been in service for several years as the Airbus A380. Attention in the aircraft industry has now shifted to two-engine aircraft with a greater emphasis on reduction of fuel burn, so the model created for Part 1 is the new efficient aircraft, a twin aimed at high efficiency.},
  googlebooks = {YVsZCgAAQBAJ},
  isbn = {978-1-107-51122-4},
  langid = {english},
  keywords = {Science / Mechanics / Fluids,Technology \& Engineering / Aeronautics \& Astronautics,Technology \& Engineering / Drafting \& Mechanical Drawing,Technology \& Engineering / Engineering (General),Technology \& Engineering / Industrial Design / General,Technology \& Engineering / Mechanical}
}

@article{dastanpourObservationsCorrelationPrimary2014,
  title = {Observations of a {{Correlation Between Primary Particle}} and {{Aggregate Size}} for {{Soot Particles}}},
  author = {Dastanpour, Ramin and Rogak, Steven N.},
  year = {2014},
  month = oct,
  journal = {Aerosol Science and Technology},
  volume = {48},
  number = {10},
  pages = {1043--1049},
  publisher = {{Taylor \& Francis}},
  issn = {0278-6826},
  doi = {10.1080/02786826.2014.955565},
  urldate = {2022-03-21},
  abstract = {For decades, soot has been modeled as fractal-like aggregates of nearly equiaxed spherules. Cluster\textendash cluster aggregation simulations, starting from a population of primary particles, give rise to structures that closely match real aerosols of solid particles produced in flames. In such simulations, primary particle size is uncorrelated with aggregate size, as all aggregates contain primary particles drawn from the same population. Aerosol measurements have been interpreted with this geometric model. Examination of transmission electron micrographs of soot samples from various sources shows that primary particle sizes are not well mixed within an aerosol population. Larger aggregates tend to contain larger primary particles and the variation in size is much larger between aggregates than within aggregates. The soot sources considered here are all substantially not well-mixed (aircraft jet engine, inverted diffusion flame, gasoline direct injection engine, heavy-duty compression ignition engine). The observed variations in primary particle size can be explained if soot aggregates are formed and grew by coagulation in small zones of the combustion chamber, prior to dilution and transport (with minimal coagulation) to the sampling system.Copyright 2014 American Association for Aerosol Research}
}

@misc{dietmullerDlrpaClimaccfDataset2022,
  title = {Dlr-Pa/Climaccf: {{Dataset}} Update for {{GMDD}}},
  shorttitle = {Dlr-Pa/Climaccf},
  author = {Dietm{\"u}ller, Simone},
  year = {2022},
  month = sep,
  doi = {10.5281/zenodo.7074582},
  urldate = {2022-12-01},
  abstract = {Calculation of algorithmic climate change functions.},
  howpublished = {Zenodo}
}

@techreport{dietmullerPythonLibraryComputing2022,
  type = {Preprint},
  title = {A Python Library for Computing Individual and Merged Non-{{CO}}\&lt;Sub\&gt;2\&lt;/Sub\&gt; Algorithmic Climate Change Functions: {{CLIMaCCF V1}}.0},
  shorttitle = {A Python Library for Computing Individual and Merged Non-{{CO}}\&lt;Sub\&gt;2\&lt;/Sub\&gt; Algorithmic Climate Change Functions},
  author = {Dietm{\"u}ller, Simone and Matthes, Sigrun and Dahlmann, Katrin and Yamashita, Hiroshi and Simorgh, Abolfazl and Soler, Manuel and Linke, Florian and L{\"u}hrs, Benjamin and Meuser, Maximilian Mendiguchia and Weder, Christian and Grewe, Volker and Yin, Feijia and Castino, Federica},
  year = {2022},
  month = oct,
  institution = {{Atmospheric sciences}},
  doi = {10.5194/gmd-2022-203},
  urldate = {2022-11-02},
  abstract = {Aviation aims to reduce its climate impact by adopting trajectories, that avoid those regions of the atmosphere where aviation emissions have a large impact. To that end, prototype algorithmic climate change functions (aCCFs) can be used, which provide spatially and temporally resolved information on aviation's climate impact in terms of future near-surface temperature change. These aCCFs can be calculated with meteorological input data obtained from e.g. numerical weather 5 prediction models. We here present the open-source Python Library called CLIMaCCF, an easy to use and flexible tool which efficiently calculates both the individual aCCFs (i.e., water vapour, nitrogen oxide (NOx) induced ozone and methane, and contrail-cirrus aCCFs) and the merged non-CO2 aCCFs that combine all these individual contributions. These merged aCCFs can be only constructed with the technical specification of aircraft/engine parameters, i.e., NOx emission indices and flown distance per kg burnt fuel. These aircraft/engine specific values are provided within CLIMaCCF version V1.0 for a set of 10 aggregated aircraft/engine classes (i.e. regional, single-aisle, wide-body). Moreover, CLIMaCCF allows by a user-friendly configuration setting to choose between a set of different physical climate metrics (i.e. average temperature response for pulse or future scenario emissions over the time horizons of 20, 50 or 100 years). Finally, we demonstrate the abilities of CLIMaCCF by a series of example applications.},
  langid = {english}
}

@article{dopelheuerInfluenceEnginePerformance1998,
  title = {Influence of Engine Performance on Emission Characteristics},
  author = {Dopelheuer, A and Lecht, M},
  year = {1998},
  journal = {Gas Turbine Engine Combustion, Emissions and Alternative Fuels},
  pages = {12},
  langid = {english}
}

@article{duboisFuelFlowMethod22006,
  title = {"{{Fuel Flow Method2}}" for {{Estimating Aircraft Emissions}}},
  author = {DuBois, Doug and Paynter, Gerald C.},
  year = {2006},
  journal = {SAE Transactions},
  volume = {115},
  eprint = {44657657},
  eprinttype = {jstor},
  pages = {1--14},
  publisher = {{SAE International}},
  issn = {0096-736X},
  urldate = {2022-03-21},
  abstract = {In recent years there has been increasing interest in quantifying the emissions from aircraft in order to generate inventories of emissions for climate models, technology and scenario studies, and inventories of emissions for airline fleets typically presented in environmental reports. The preferred method for calculating aircraft engine emissions of NOx, HC, and CO is the proprietary "P3T3" method. This method relies on proprietary airplane and engine performance models along with proprietary engine emissions characterizations. In response and in order to provide a transparent method for calculating aircraft engine emissions non proprietary fuel flow based methods1,2,3 have been developed. This paper presents derivation, updates, and clarifications of the fuel flow method methodology known as "Fuel Flow Method 2" While not as rigorous as the P3T3 method used for emissions certification, fuel flow methods can give reasonable approximations of emissions on the order of {$\pm$} 10 to 15\% for NOx as compared to the P3T3 method. In depth studies of variation for HC and CO have not been undertaken, though a limited examination of the data indicates a much broader spread, with a range on the low end similar to NOx, while up to almost a factor of two on the high end, depending on engine and thrust rating.}
}

@book{duffieSolarEngineeringThermal1991,
  title = {Solar {{Engineering}} of {{Thermal Processes}}},
  author = {Duffie, John A. and Beckman, William A.},
  year = {1991},
  publisher = {{Wiley}},
  abstract = {Many of the newest developments in solar energy science and technology are covered in this Second Edition. There is a thorough up-to-date review of solar energy principles and the functioning, design and economics of solar thermal processes. Convection and radiation, properties of materials, components, systems and applications to active space and water heating are discussed. Includes examples and problems of tabulated radiation data and conversion factors.},
  googlebooks = {KEyFAAAACAAJ},
  isbn = {978-0-471-51056-7},
  langid = {english},
  keywords = {Science / Light,Technology \& Engineering / Manufacturing,Technology \& Engineering / Mechanical,Technology \& Engineering / Power Resources / General}
}

@article{eckelCalibratedProbabilisticQuantitative1998,
  title = {Calibrated {{Probabilistic Quantitative Precipitation Forecasts Based}} on {{theMRF Ensemble}}},
  author = {Eckel, F. Anthony and Walters, Michael K.},
  year = {1998},
  month = dec,
  journal = {Weather and Forecasting},
  volume = {13},
  number = {4},
  pages = {1132--1147},
  publisher = {{American Meteorological Society}},
  issn = {1520-0434, 0882-8156},
  doi = {10.1175/1520-0434(1998)013<1132:CPQPFB>2.0.CO;2},
  urldate = {2023-05-12},
  abstract = {Abstract Probabilistic quantitative precipitation forecasts (PQPFs) based on the National Centers for Environmental Prediction Medium-Range Forecast (MRF) ensemble currently perform below their full potential quality (i.e., accuracy and reliability). This unfulfilled potential is due to the MRF ensemble being adversely affected by systematic errors that arise from an imperfect forecast model and less than optimum ensemble initial perturbations. This research sought to construct a calibration to account for these systematic errors and thus produce higher quality PQPFs. The main tool of the calibration was the verification rank histogram, which can be used to interpret and adjust an ensemble forecast. Using a large training dataset, many histograms were created, each characterized by a different forecast lead time and level of ensemble variability. These results were processed into probability surfaces, providing detailed information on performance of the ensemble as part of the calibration scheme. Improvement of the calibrated PQPF over the current uncalibrated PQPF was examined using a separate, large forecasting dataset, with climatological PQPF as the baseline. While the calibration technique noticeably improved the quality of PQPF and extended predictability by about 1 day, its usefulness was bounded by the intrinsic predictability limits of cumulative precipitation. Predictability was found to be dependent upon the precipitation category. For significant levels of precipitation (high thresholds), the calibration designed in this research was found to be useful only for short-range PQPFs. For low precipitation thresholds, the calibrated PQPF did prove to be of value in the medium range.},
  chapter = {Weather and Forecasting},
  langid = {english}
}

@misc{eurocontrolUSERMANUALBASE2010,
  title = {{{USER MANUAL FOR THE BASE OF Aircraft DATA}} ({{BADA}}) {{REVISION}} 3.8},
  author = {Eurocontrol},
  year = {2010},
  month = apr,
  publisher = {{EUROCONTROL EXPERIMENTAL CENTRE}},
  doi = {10.1163/1570-6664_iyb_SIM_org_39214},
  urldate = {2023-02-15},
  abstract = {The Base of Aircraft Data (BADA) provides a set of ASCII files containing performance and operating procedure coefficients for 318 different aircraft types. The coefficients include those used to calculate thrust, drag and fuel flow and those used to specify nominal cruise, climb and descent speeds. User Manual for Revision 3.8 of BADA provides definitions of each of the coefficients and then explains the file formats. Instructions for remotely accessing the files via Internet are also given.},
  langid = {english}
}

@article{fritzRolePlumescaleProcesses2020,
  title = {The Role of Plume-Scale Processes in Long-Term Impacts of Aircraft Emissions},
  author = {Fritz, Thibaud M. and Eastham, Sebastian D. and Speth, Raymond L. and Barrett, Steven R. H.},
  year = {2020},
  month = may,
  journal = {Atmospheric Chemistry and Physics},
  volume = {20},
  number = {9},
  pages = {5697--5727},
  publisher = {{Copernicus GmbH}},
  issn = {1680-7316},
  doi = {10.5194/acp-20-5697-2020},
  urldate = {2022-02-15},
  abstract = {{$<$}p{$><$}strong class="journal-contentHeaderColor"{$>$}Abstract.{$<$}/strong{$>$} Emissions from aircraft engines contribute to atmospheric NO\textsubscript{\emph{x}}, 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.{$<$}/p{$>$} {$<$}p{$>$}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\textendash 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 long-term (24\&thinsp;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 {$\sim$}200\&thinsp;\% at cruise altitudes. Instant dilution of emissions also underestimates the fraction of remaining NO\textsubscript{\emph{x}}, 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\&thinsp;\% 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 {$\sim$}5\&thinsp;\% to 15\&thinsp;\% sooner and are 10\&thinsp;\% to 22\&thinsp;\% optically thinner. The conversion of emitted NO\textsubscript{\emph{x}} to HNO\textsubscript{3} and N\textsubscript{2}O\textsubscript{5} falls by 16\&thinsp;\% and 33\&thinsp;\%, 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.{$<$}/p{$>$}},
  langid = {english}
}

@article{holzapfelProbabilisticTwoPhaseWake2003,
  title = {Probabilistic {{Two-Phase Wake Vortex Decay}} and {{Transport Model}}},
  author = {Holz{\"a}pfel, Frank},
  year = {2003},
  month = mar,
  journal = {Journal of Aircraft},
  volume = {40},
  number = {2},
  pages = {323--331},
  publisher = {{American Institute of Aeronautics and Astronautics}},
  doi = {10.2514/2.3096},
  urldate = {2022-03-21},
  keywords = {Atmospheric Boundary Layer,Atmospheric Turbulence,Buoyancy Force,Dallas/Fort Worth International Airport,Large Eddy Simulation,LIDAR,Richardson Number,Shear Layers,Viscosity,Wake Vortex Measurements}
}

@article{jensenSpreadingGrowthContrails1998,
  title = {Spreading and Growth of Contrails in a Sheared Environment},
  author = {Jensen, Eric J. and Ackerman, Andrew S. and Stevens, David E. and Toon, {\relax Owen}. B. and Minnis, Patrick},
  year = {1998},
  journal = {Journal of Geophysical Research: Atmospheres},
  volume = {103},
  number = {D24},
  pages = {31557--31567},
  issn = {2156-2202},
  doi = {10.1029/98JD02594},
  urldate = {2023-03-24},
  abstract = {A case study of persistent contrail evolution in a sheared environment is simulated over time-scales of 15\textendash 180 min using a large-eddy simulation model with detailed microphysics. Model results are compared to satellite and in situ measurements of persistent contrails from the Subsonic Aircraft: Contrail and Cloud Effects Special Study (SUCCESS) experiment. In simulations with large ambient supersaturations and moderate wind shear, crystals with lengths {$>$} 200 {$\mu$}m are generated within 45 min by depositional growth. These crystals fall rapidly, and the contrail horizontal extent increases due to the wind shear. Strong radiative heating (with rates up to 10 K d-1) drives a local updraft and lofts the contrail core several hundred meters. The observed rate of contrail spreading and maintenance of optical depths larger than 0.05 can be approximately explained simply by growth and precipitation of ice crystals nucleated during the initial contrail formation if the environmental humidity is very high (relative humidity with respect to ice {$>$}125\%). This result is consistent with observed high humidities in regions where persistent contrails formed during SUCCESS.},
  langid = {english}
}

@article{khanEmissionsWaterVapour2022,
  title = {The {{Emissions}} of {{Water Vapour}} and {{NOx}} from {{Modelled Hydrogen-Fuelled Aircraft}} and the {{Impact}} of {{NOx Reduction}} on {{Climate Compared}} with {{Kerosene-Fuelled Aircraft}}},
  author = {Khan, M. Anwar H. and Brierley, Joel and Tait, Kieran N. and Bullock, Steve and Shallcross, Dudley E. and Lowenberg, Mark H.},
  year = {2022},
  month = oct,
  journal = {Atmosphere},
  volume = {13},
  number = {10},
  pages = {1660},
  publisher = {{Multidisciplinary Digital Publishing Institute}},
  issn = {2073-4433},
  doi = {10.3390/atmos13101660},
  urldate = {2023-03-24},
  abstract = {A kerosene fuelled aircraft was modelled within a performance tool and fuel burn and the emissions of nitrogen oxides (NOx) and water vapour at different stages of flight throughout the mission were estimated. Adaptions were made to engine and aircraft parameters within the performance tool to accommodate a liquid hydrogen fuel over the same given mission. Once an iterative design process had been completed to ensure the aircraft could perform the given mission, the performance tool was again used to calculate total fuel burn. Fuel burn results alongside predicted emission indices were used to estimate the emissions of NOx, water vapour from hydrogen-fuelled aircraft. The use of hydrogen fuel over kerosene fuel in the modelled aircraft resulted in the removal of carbon-based emission species alongside 86\% reduction in NOx and 4.3 times increase in water vapour emission. The climate impact of this switch with the reduction in NOx emission was assessed by a 3D global atmospheric chemistry and transport model, STOCHEM-CRI, which found a significant reduction in the concentration of a potent greenhouse gas, ozone, and an oxidizing agent, OH, by up to 6\% and 25\%, respectively. The reduction of OH levels could induce a positive radiative forcing effect as the lifetime of another important greenhouse gas, methane, is increased. However, the magnitude of this increase is very small (\textasciitilde 0.3\%), thus the overall impact of the reduction in NOx emissions is likely to have a net negative radiative forcing effect, improving aviation's impact on the environment. However, further work is warranted on effects of other emission species, specifically water vapour, particulate matter and unburned hydrogen.},
  copyright = {http://creativecommons.org/licenses/by/3.0/},
  langid = {english},
  keywords = {aviation industry,greenhouse gas,kerosene fuel,liquid hydrogen,radiative forcing}
}

@article{leeContributionGlobalAviation2021,
  title = {The Contribution of Global Aviation to Anthropogenic Climate Forcing for 2000 to 2018},
  author = {Lee, D.S. and Fahey, D.W. and Skowron, A. and Allen, M.R. and Burkhardt, U. and Chen, Q. and Doherty, S.J. and Freeman, S. and Forster, P.M. and Fuglestvedt, J. and Gettelman, A. and De Le{\'o}n, R.R. and Lim, L.L. and Lund, M.T. and Millar, R.J. and Owen, B. and Penner, J.E. and Pitari, G. and Prather, M.J. and Sausen, R. and Wilcox, L.J.},
  year = {2021},
  month = jan,
  journal = {Atmospheric Environment},
  volume = {244},
  pages = {117834},
  issn = {13522310},
  doi = {10.1016/j.atmosenv.2020.117834},
  urldate = {2021-03-22},
  langid = {english}
}

@misc{megginsonOpendataDownloadsOurAirports2023,
  title = {Open-Data Downloads for {{OurAirports}}},
  author = {Megginson, David},
  year = {2023},
  month = apr,
  urldate = {2023-04-12},
  abstract = {Open-data downloads for OurAirports.com},
  copyright = {Unlicense}
}

@misc{noaaSolarCalculationDetails,
  title = {Solar {{Calculation Details}}},
  author = {NOAA},
  urldate = {2023-02-15},
  abstract = {The Global Monitoring Laboratory conducts research on greenhouse gas and carbon cycle feedbacks, changes in clouds, aerosols, and surface radiation, and recovery of stratospheric ozone.},
  howpublished = {https://gml.noaa.gov/grad/solcalc/calcdetails.html},
  langid = {american}
}

@book{paltridgeRadiativeProcessesMeteorology1976,
  title = {Radiative {{Processes}} in {{Meteorology}} and {{Climatology}}},
  author = {Paltridge, G. W. and Platt, C. Martin R. and Platt, C. M. R.},
  year = {1976},
  publisher = {{Elsevier Scientific Publishing Company}},
  googlebooks = {sDBRAAAAMAAJ},
  isbn = {978-0-444-41444-1},
  langid = {english}
}

@article{parkMeasurementInherentMaterial2004,
  title = {Measurement of {{Inherent Material Density}} of {{Nanoparticle Agglomerates}}},
  author = {Park, Kihong and Kittelson, David B. and Zachariah, Michael R. and McMurry, Peter H.},
  year = {2004},
  month = jun,
  journal = {Journal of Nanoparticle Research},
  volume = {6},
  number = {2},
  pages = {267--272},
  issn = {1572-896X},
  doi = {10.1023/B:NANO.0000034657.71309.e6},
  urldate = {2022-03-21},
  abstract = {We describe a new technique to measure the size dependent inherent material density of chain agglomerate particles. Measurements were carried out for diesel soot and aluminum/alumina agglomerate particles in the nanometer size range. Transmission electron microscopy was used to measure the volumes of agglomerate particles that were preselected by mass using an aerosol particle mass analyzer. We found that the density of diesel exhaust particles increased from 1.27 to 1.78g/cm3 as particle mobility size increased from 50 to 220nm. When particles are preheated to remove volatile components, the density was 1.77{$\pm$}0.07g/cm3, independent of particle size. The densities measured after heating correspond to the inherent material density of diesel soot. Measurements with aluminum nanoparticles were made downstream of a furnace where aluminum (Al) was converted to alumina (Al2O3). From measurements of inherent material density we were able to infer the extent of reaction, which varied with furnace temperature.},
  langid = {english}
}

@article{ponaterContrailsComprehensiveGlobal2002,
  title = {Contrails in a Comprehensive Global Climate Model: {{Parameterization}} and Radiative Forcing Results},
  shorttitle = {Contrails in a Comprehensive Global Climate Model},
  author = {Ponater, Michael},
  year = {2002},
  journal = {Journal of Geophysical Research},
  volume = {107},
  number = {D13},
  pages = {4164},
  issn = {0148-0227},
  doi = {10.1029/2001JD000429},
  urldate = {2021-01-25},
  langid = {english}
}

@article{reutterIceSupersaturatedRegions2020,
  title = {Ice Supersaturated Regions: Properties and Validation of {{ERA-Interim}} Reanalysis with {{IAGOS}} in Situ Water Vapour Measurements},
  shorttitle = {Ice Supersaturated Regions},
  author = {Reutter, Philipp and Neis, Patrick and Rohs, Susanne and Sauvage, Bastien},
  year = {2020},
  month = jan,
  journal = {Atmospheric Chemistry and Physics},
  volume = {20},
  number = {2},
  pages = {787--804},
  issn = {1680-7324},
  doi = {10.5194/acp-20-787-2020},
  urldate = {2021-07-23},
  abstract = {Abstract. Cirrus clouds and their potential formation regions, so-called ice supersaturated regions (ISSRs), with values of relative humidity with respect to ice exceeding 100\,\%, occur frequently in the tropopause region. It is assumed that ISSRs and cirrus clouds can change the tropopause structure by diabatic processes, driven by latent heating due to phase transition and interaction with radiation. For many research questions, a three-dimensional picture including a sufficient temporal resolution of the water vapour fields in the tropopause region is required. This requirement is fulfilled nowadays by reanalysis products such as the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim reanalysis. However, for a meaningful investigation of water vapour in the tropopause region, a comparison of the reanalysis data with measurement is advisable, since it is difficult to measure water vapour and to assimilate meaningful measurements into reanalysis products. Here, we present an intercomparison of high-resolution in situ measurements aboard passenger aircraft within the European Research Infrastructure IAGOS (In-service Aircraft for a Global Observing System; http://www.iagos.org, last access: 15~January 2020) with ERA-Interim. Temperature and humidity data over the North Atlantic from 2000 to 2009 are compared relative to the dynamical tropopause. The comparison of the temperature shows good agreement between the measurement and ERA-Interim. While ERA-Interim also shows the main features of the water vapour measurements of IAGOS, the variability of the data is clearly smaller in the reanalysis data set. The combination of temperature and water vapour leads to the relative humidity with respect to ice (RHi). Here, ERA-Interim deviates from the measurements concerning values larger than RHi=100\,\%, both in number and strength of supersaturation. Also, pathlengths of ISSRs along flight tracks are investigated, representing macrophysical properties as linked to atmospheric flows. The comparison of ISSR pathlengths shows distinct differences, which can be traced back to the spatial resolution of both data sets. Also, the seasonal cycle and height dependence of pathlengths changes for the different data sets due to their spatial resolution. IAGOS shows a significantly greater amount of smaller ISSRs compared to ERA-Interim. Good agreement begins only at pathlengths on the order of the ERA-Interim spatial resolution and larger.},
  langid = {english}
}

@article{schrippAircraftEngineParticulate2022,
  title = {Aircraft Engine Particulate Matter Emissions from Sustainable Aviation Fuels: {{Results}} from Ground-Based Measurements during the {{NASA}}/{{DLR}} Campaign {{ECLIF2}}/{{ND-MAX}}},
  shorttitle = {Aircraft Engine Particulate Matter Emissions from Sustainable Aviation Fuels},
  author = {Schripp, Tobias and Anderson, Bruce E. and Bauder, Uwe and Rauch, Bastian and Corbin, Joel C. and Smallwood, Greg J. and Lobo, Prem and Crosbie, Ewan C. and Shook, Michael A. and {Miake-Lye}, Richard C. and Yu, Zhenhong and Freedman, Andrew and Whitefield, Philip D. and Robinson, Claire E. and Achterberg, Steven L. and K{\"o}hler, Markus and O{\ss}wald, Patrick and Grein, Tobias and Sauer, Daniel and Voigt, Christiane and Schlager, Hans and LeClercq, Patrick},
  year = {2022},
  month = oct,
  journal = {Fuel},
  volume = {325},
  pages = {124764},
  issn = {0016-2361},
  doi = {10.1016/j.fuel.2022.124764},
  urldate = {2023-03-24},
  abstract = {The use of alternative jet fuels by commercial aviation has increased substantially in recent years. Beside the reduction of carbon dioxide emission, the use of sustainable aviation fuels (SAF) may have a positive impact on the reduction of particulate emissions. This study summarizes the results from a ground-based measurement activity conducted in January 2018 as part of the ECLIF2/ND-MAX campaign in Ramstein, Germany. Two fossil reference kerosenes and three different blends with the renewable fuel component HEFA-SPK (Hydroprocessed Esters and Fatty Acids Synthetic Paraffinic Kerosene) were burned in an A320 with V2527-A5 engines to investigate the effect of fuel naphthalene/aromatic content and the corresponding fuel hydrogen content on non-volatile particle number and mass emissions. Reductions up to 70\% in non-volatile particle mass emission compared to the fossil reference fuel were observed at low power settings. The reduction trends to decrease with increasing power settings. The fuels showed a decrease in particle emission with increasing fuel hydrogen content. Consequently, a second fossil fuel with similar hydrogen content as one of the HEFA blends featured similar reduction factors in particle mass and number. Changes in the fuel naphthalene content had significant impact on the particle number emission. A comparison to in-flight emission data shows similar trends at cruise altitudes. The measurements highlight the importance of individual fuel components in regulating engine emissions, particularly at the low thrust settings typically employed during ground operations (e.g. during idle and taxi). Therefore, when selecting and mixing SAF blends to meet present fuel-certification standards, attention should be paid to minimizing complex aromatic content to achieve the greatest possible air quality and climate benefits.},
  langid = {english},
  keywords = {HEFA,SAF,Sustainability,Ultra-fine particles}
}

@article{schumannAirTrafficContrail2021,
  title = {Air Traffic and Contrail Changes over {{Europe}} during {{COVID-19}}: A Model Study},
  shorttitle = {Air Traffic and Contrail Changes over {{Europe}} during {{COVID-19}}},
  author = {Schumann, Ulrich and Poll, Ian and Teoh, Roger and Koelle, Rainer and Spinielli, Enrico and Molloy, Jarlath and Koudis, George S. and Baumann, Robert and Bugliaro, Luca and Stettler, Marc and Voigt, Christiane},
  year = {2021},
  month = may,
  journal = {Atmospheric Chemistry and Physics},
  volume = {21},
  number = {10},
  pages = {7429--7450},
  issn = {1680-7324},
  doi = {10.5194/acp-21-7429-2021},
  urldate = {2023-03-20},
  abstract = {Abstract. The strong reduction of air traffic during the COVID-19 pandemic provides a unique test case for the relationship between air traffic density, contrails, and their radiative forcing of climate change. Here, air traffic and contrail cirrus changes are quantified for a European domain for March to August 2020 and compared to the same period in 2019. Traffic data show a 72\,\% reduction in flight distance compared with 2019. This paper investigates the induced contrail changes in a model study. The contrail model results depend on various methodological details as discussed in parameter studies. In the reference case, the reduced traffic caused a reduction in contrail length. The reduction is slightly stronger than expected from the traffic change because the weather conditions in 2020 were less favorable for contrail formation than in 2019. Contrail coverage over Europe with an optical depth larger than 0.1 decreased from 4.6\,\% in 2019 to 1.4\,\% in 2020; the total cirrus cover amount changed by 28\,\% to 25\,\%. The reduced contrail coverage caused 70\,\% less longwave and 73\,\% less shortwave radiative forcing but, because of various nonlinearities, only 54\,\% less net forcing in this case. The methods include recently developed models for performance parameters and soot emissions. The overall propulsion efficiency of the aircraft is about 20\,\% smaller than estimated in earlier studies, resulting in 3\,\% fewer contrails. Considerable sensitivity to soot emissions is found, highlighting fuel and engine importance. The contrail model includes a new approximate method to account for water vapor exchange between contrails and background air and for radiative forcing changes due to contrail\textendash contrail overlap. The water vapor exchange reduces available ice supersaturation in the atmosphere, which is critical for contrail formation. Contrail\textendash contrail overlap changes the computed radiative forcing considerably. Comparisons to satellite observations are described and discussed in a parallel publication.},
  langid = {english}
}

@article{schumannAviationContrailCirrus2021,
  title = {Aviation {{Contrail Cirrus}} and {{Radiative Forcing Over Europe During}} 6 {{Months}} of {{COVID-19}}},
  author = {Schumann, U. and Bugliaro, L. and D{\"o}rnbrack, A. and Baumann, R. and Voigt, C.},
  year = {2021},
  journal = {Geophysical Research Letters},
  volume = {48},
  number = {8},
  pages = {e2021GL092771},
  issn = {1944-8007},
  doi = {10.1029/2021GL092771},
  urldate = {2023-01-19},
  abstract = {The COVID-19 pandemic led to a 72\% reduction of air traffic over Europe in March\textendash August 2020 compared to 2019. Modeled contrail cover declined similarly, and computed mean instantaneous radiative contrail forcing dropped regionally by up to 0.7 W m-2. Here, model predictions of cirrus optical thickness and the top-of-atmosphere outgoing longwave and reflected shortwave irradiances are tested by comparison to Meteosat-SEVIRI-derived data. The agreement between observations and modeled data is slightly better when modeled contrail cirrus contributions are included. The spatial distributions and diurnal cycles of the differences in these data between 2019 and 2020 are partially caused by differences in atmospheric and surface conditions, particularly for solar radiation in the spring of 2020. Aviation signals become discernible in the observed differences of these data between 2019 and 2020 when subtracting numerical weather prediction model results that approximate the atmosphere and surface conditions without contrails.},
  langid = {english},
  keywords = {aviation,cirrus,contrail,COVID-19,radiative forcing,satellite}
}

@article{schumannAviationinducedCirrusRadiation2013,
  title = {Aviation-Induced Cirrus and Radiation Changes at Diurnal Timescales},
  shorttitle = {Aviation-Induced Cirrus and Radiation Changes at Diurnal Timescales},
  author = {Schumann, Ulrich and Graf, Kaspar},
  year = {2013},
  month = mar,
  journal = {Journal of Geophysical Research: Atmospheres},
  volume = {118},
  number = {5},
  pages = {2404--2421},
  issn = {2169897X},
  doi = {10.1002/jgrd.50184},
  urldate = {2022-06-27},
  langid = {english}
}

@article{schumannConditionsContrailFormation1996,
  title = {On Conditions for Contrail Formation from Aircraft Exhausts ({{\"Uber Bedingungen}} Zur {{Bildung}} von {{Kondensstreifen}} Aus {{Flugzeugabgasen}})},
  author = {Schumann, Ulrich},
  year = {1996},
  month = mar,
  journal = {Meteorologische Zeitschrift},
  volume = {5},
  number = {1},
  pages = {4--23},
  issn = {0941-2948},
  doi = {10.1127/metz/5/1996/4},
  urldate = {2021-02-03},
  langid = {english}
}

@inproceedings{schumannContrailCirrusPrediction2010,
  title = {A Contrail Cirrus Prediction Tool},
  booktitle = {Proceedings of the 2nd {{International Conference}} on {{Transport}}, {{Atmosphere}} and {{Climate}} ({{TAC-2}})},
  author = {Schumann, Ulrich},
  editor = {Sausen, Robert and van Velthoven, Peter F. J. and Br{\"u}ning, Claus and Blum, Anja},
  year = {2010},
  volume = {2010--10},
  pages = {69--74},
  publisher = {{DLR}},
  address = {{Aachen, Germany and Maastricht, The Netherlands}},
  issn = {1434-8454},
  urldate = {2023-04-16},
  abstract = {An new ``Contrail Cirrus Prediction Tool'' (CoCiP) has been developed to simulate contrail cirrus resulting from a single flight as well as from a fleet of cruising aircraft, flight by flight, regionally or globally. The method predicts contrail cirrus for given air traffic and weather prediction data. The method describes the life cycle of each contrail individually using a Lagrangian Gaussian plume model with simple bulk contrail ice properties, without feedback to meteorology. Contrails are initiated when the Schmidt-Appleman criterion is satisfied and when the ambient atmosphere is humid enough to allow for contrail persistence. The initial plume properties reflect properties of the originating aircraft. The evolution of individual contrails of cruising aircraft is computed using wind, temperature, humidity, and ice water content from numerical weather prediction (NWP) output. The plume trajectory follows horizontal and vertical wind. The model simulates shear and turbulence driven spreading, ice water content as a function of ice supersaturation, and some ice particle loss processes (turbulent mixing, aggregation and sedimentation). Radiative cloud forcing is estimated for the sum of all contrails using radiative fluxes without contrails from NWP output. The tool is kept simple to allow for efficient contrail simulations. The method has been tested for case studies with some comparisons to observations. The most critical input parameter is the NWP humidity field. The results compare favourably with observations and support interpretations of insitu, satellite and lidar observed aviation impact on cirrus clouds. CoCiP can be used to predict and minimize the climate impact of contrails.},
  langid = {english}
}

@article{schumannContrailCirrusPrediction2012,
  title = {A Contrail Cirrus Prediction Model},
  author = {Schumann, U.},
  year = {2012},
  month = may,
  journal = {Geoscientific Model Development},
  volume = {5},
  number = {3},
  pages = {543--580},
  issn = {1991-9603},
  doi = {10.5194/gmd-5-543-2012},
  urldate = {2021-01-25},
  abstract = {A new model to simulate and predict the properties of a large ensemble of contrails as a function of given air traffic and meteorology is described. The model is designed for approximate prediction of contrail cirrus cover and analysis of contrail climate impact, e.g. within aviation system optimization processes. The model simulates the full contrail life-cycle. Contrail segments form between waypoints of individual aircraft tracks in sufficiently cold and humid air masses. The initial contrail properties depend on the aircraft. The advection and evolution of the contrails is followed with a Lagrangian Gaussian plume model. Mixing and bulk cloud processes are treated quasi analytically or with an effective numerical scheme. Contrails disappear when the bulk ice content is sublimating or precipitating. The model has been implemented in a ``Contrail Cirrus Prediction Tool'' (CoCiP). This paper describes the model assumptions, the equations for individual contrails, and the analysis-method for contrailcirrus cover derived from the optical depth of the ensemble of contrails and background cirrus. The model has been applied for a case study and compared to the results of other models and in-situ contrail measurements. The simple model reproduces a considerable part of observed contrail properties. Mid-aged contrails provide the largest contributions to the product of optical depth and contrail width, important for climate impact.},
  langid = {english}
}

@incollection{schumannContrailsVisibleAviation2012,
  title = {Contrails: {{Visible Aviation Induced Climate Impact}}},
  shorttitle = {Contrails},
  booktitle = {Atmospheric {{Physics}}},
  author = {Schumann, Ulrich and Graf, Kaspar and Mannstein, Hermann and Mayer, Bernhard},
  editor = {Schumann, Ulrich},
  year = {2012},
  pages = {239--257},
  publisher = {{Springer Berlin Heidelberg}},
  address = {{Berlin, Heidelberg}},
  doi = {10.1007/978-3-642-30183-4_15},
  urldate = {2022-06-04},
  abstract = {Contrails are aircraft induced linear ice particle clouds. In ice-supersaturated air masses, contrails persist and develop into contrail cirrus. Aviation changes cloudiness also by soot emissions and other aerosols. In the global mean, contrail cirrus warms the atmosphere. The local warming induced by a contrail varies strongly relative to the global mean, and may be positive or negative, depending on aircraft, route, solar and Earth-atmosphere parameters. Here we summarize present knowledge on contrails with respect to aviation and atmospheric research.},
  isbn = {978-3-642-30182-7 978-3-642-30183-4},
  langid = {english}
}

@article{schumannDehydrationEffectsContrails2015,
  title = {Dehydration Effects from Contrails in a Coupled Contrail\textendash Climate Model},
  author = {Schumann, U. and Penner, J. E. and Chen, Yibin and Zhou, Cheng and Graf, K.},
  year = {2015},
  month = oct,
  journal = {Atmospheric Chemistry and Physics},
  volume = {15},
  number = {19},
  pages = {11179--11199},
  issn = {1680-7324},
  doi = {10.5194/acp-15-11179-2015},
  urldate = {2021-08-09},
  abstract = {The uptake of water by contrails in icesupersaturated air and the release of water after ice particle advection and sedimentation dehydrates the atmosphere at flight levels and redistributes humidity mainly to lower levels. The dehydration is investigated by coupling a plumescale contrail model with a global aerosol\textendash climate model. The contrail model simulates all the individual contrails forming from global air traffic for meteorological conditions as defined by the climate model. The computed contrail cirrus properties compare reasonably with theoretical concepts and observations. The mass of water in aged contrails may exceed 106 times the mass of water emitted from aircraft. Many of the ice particles sediment and release water in the troposphere, on average 700 m below the mean flight levels. Simulations with and without coupling are compared. The drying at contrail levels causes thinner and longer-lived contrails with about 15 \% reduced contrail radiative forcing (RF). The reduced RF from contrails is on the order of 0.06 W m-2, slightly larger than estimated earlier because of higher soot emissions. For normal traffic, the RF from dehydration is small compared to interannual variability. A case with emissions increased by 100 times is used to overcome statistical uncertainty. The contrails impact the entire hydrological cycle in the atmosphere by reducing the total water column and the cover by high- and low-level clouds. For normal traffic, the dehydration changes contrail RF by positive shortwave and negative longwave contributions on the order of 0.04 W m-2, with a small negative net RF. The total net RF from contrails and dehydration remains within the range of previous estimates.},
  langid = {english}
}

@inproceedings{schumannDeterminationContrailsSatellite1990,
  title = {Determination of {{Contrails}} from {{Satellite Data}} and {{Observational Results}}},
  booktitle = {Air {{Traffic}} and the {{Environment}} \textemdash{} {{Background}}, {{Tendencies}} and {{Potential Global Atmospheric Effects}}},
  author = {Schumann, U. and Wendling, P.},
  editor = {Schumann, U.},
  year = {1990},
  series = {Lecture {{Notes}} in {{Engineering}}},
  pages = {138--153},
  publisher = {{Springer}},
  address = {{Berlin, Heidelberg}},
  doi = {10.1007/978-3-642-51686-3_9},
  abstract = {Condensation trails (contrails) from air traffic in the upper troposphere may have an effect on the earth's climate. We first discuss the state of knowledge. Then some results of radiation transfer calculations are reported which help to estimate the order of magnitude of the effects of cirrus clouds and water vapour in comparison to doubling of the concentration of CO2. The main part of the paper describes the analysis of contrails from satellite data. Based on NOAA-AVHRR data we present results for a specific case where contrails covered a few percent of a region including southern Germany and the Alps. Preliminary results are reported for 99 further cases. A pattern recognition method is described to identify contrails and the related cloud cover automatically. Laser observations reflect contrail cross-sections which are several km in width and about 700 m thick. The optical thickness reaches values up to 1.},
  isbn = {978-3-642-51686-3},
  langid = {english},
  keywords = {Advanced Very High Resolution Radiometer,Cloud Cover,Optical Thickness,Sunshine Duration}
}

@article{schumannEffectiveRadiusIce2011,
  title = {Effective {{Radius}} of {{Ice Particles}} in {{Cirrus}} and {{Contrails}}},
  author = {Schumann, U. and Mayer, B. and Gierens, K. and Unterstrasser, S. and Jessberger, P. and Petzold, A. and Voigt, C. and Gayet, J.-F.},
  year = {2011},
  month = feb,
  journal = {Journal of the Atmospheric Sciences},
  volume = {68},
  number = {2},
  pages = {300--321},
  publisher = {{American Meteorological Society}},
  issn = {0022-4928, 1520-0469},
  doi = {10.1175/2010JAS3562.1},
  urldate = {2022-02-21},
  abstract = {Abstract This paper discusses the ratio C between the volume mean radius and the effective radius of ice particles in cirrus and contrails. The volume mean radius is proportional to the third root of the ratio between ice water content and number of ice particles, and the effective radius measures the ratio between ice particle volume and projected cross-sectional area. For given ice water content and number concentration of ice particles, the optical depth scales linearly with C. Hence, C is an important input parameter for radiative forcing estimates. The ratio C in general depends strongly on the particle size distribution (PSD) and on the particle habits. For constant habits, C can be factored into a PSD and a habit factor. The PSD factor is generally less than one, while the habit factor is larger than one for convex or concave ice particles with random orientation. The value of C may get very small for power-law PSDs with exponent n between -4 and 0, which is often observed. For such PSDs, most of the particle volume is controlled by a few large particles, while most of the cross-sectional area is controlled by the many small particles. A new particle habit mix for contrail cirrus including small droxtal-shape particles is suggested. For measured cirrus and contrails, the dependence of C on volume mean particle radius, ambient humidity, and contrail age is determined. For cirrus, C varies typically between 0.4 and 1.1. In contrails, C = 0.7 {$\pm$} 0.3, with uncertainty ranges increasing with the volume radius and contrail age. For the small particles in young contrails, the extinction efficiency in the solar range deviates considerably from the geometric optics limit.},
  chapter = {Journal of the Atmospheric Sciences},
  langid = {english}
}

@article{schumannLifeCycleIndividual2017,
  title = {On the {{Life Cycle}} of {{Individual Contrails}} and {{Contrail Cirrus}}},
  author = {Schumann, Ulrich and Heymsfield, Andrew J.},
  year = {2017},
  month = jan,
  journal = {Meteorological Monographs},
  volume = {58},
  number = {1},
  pages = {3.1-3.24},
  publisher = {{American Meteorological Society}},
  doi = {10.1175/AMSMONOGRAPHS-D-16-0005.1},
  urldate = {2022-02-19},
  abstract = {Abstract The life cycle of individual (initially line shaped) contrails behind aircraft and of contrail cirrus (aged contrails mixed with other ice clouds) is described. The full contrail life cycle is covered, from ice formation for given water, heat, and particulate emissions; to changes in the jet, wake, and dispersion phases; through final sublimation or sedimentation. Contrail properties are deduced from various in situ, remote sensing, and model studies. Aerodynamically induced contrails and distrails are explained briefly. Contrails form both in clear air and inside cirrus. Young contrails consume most of the ambient ice supersaturation. Optical properties of contrails are age and humidity dependent. Contrail occurrence and radiative forcing depends on the ambient Earth\textendash atmosphere conditions. Contrail cirrus seems to be optically thicker than assessed previously and may not only increase cirrus coverage but also thicken existing cirrus. Some observational constraints for contrail cirrus occurrence and radiative forcing are derived. Key parameters controlling contrail properties\textemdash besides aircraft and fuel properties, ambient pressure, temperature, and humidity\textemdash are the number of ice particles per flight distance surviving the wake vortex phase, the contrail depth, and particle sedimentation, wind shear, turbulence, and vertical motions controlling contrail dispersion. The climate impact of contrails depends among other things on the ratio of shortwave to longwave radiative forcing (RF) and on the efficacy with which contrail RF contributes to surface warming. Several open issues are identified, including renucleation from residuals of sublimated contrail ice particles.},
  chapter = {Meteorological Monographs},
  langid = {english}
}

@article{schumannParametricRadiativeForcing2012,
  title = {A {{Parametric Radiative Forcing Model}} for {{Contrail Cirrus}}},
  author = {Schumann, U. and Mayer, B. and Graf, K. and Mannstein, H.},
  year = {2012},
  month = jul,
  journal = {Journal of Applied Meteorology and Climatology},
  volume = {51},
  number = {7},
  pages = {1391--1406},
  issn = {1558-8424, 1558-8432},
  doi = {10.1175/JAMC-D-11-0242.1},
  urldate = {2021-02-09},
  abstract = {A new parameterized analytical model is presented to compute the instantaneous radiative forcing (RF) at the top of the atmosphere (TOA) produced by an additional thin contrail cirrus layer (called ``contrail'' below). The model calculates the RF using as input the outgoing longwave radiation and reflected solar radiation values at TOA for a contrail-free atmosphere, so that the model is applicable for both cloud-free and cloudy ambient atmospheres. Additional input includes the contrail temperature, contrail optical depth (at 550 nm), effective particle radius, particle habit, solar zenith angle, and the optical depth of cirrus above the contrail layer. The model parameters (5 for longwave and 10 for shortwave) are determined from least squares fits to calculations from the ``libRadtran'' radiative transfer model over a wide range of atmospheric and surface conditions. The correlation coefficient between model and calculations is larger than 98\%. The analytical model is compared with published results, including a 1-yr simulation of global RF, and is found to agree well with previous studies. The fast analytical model is part of a larger modeling system to simulate contrail life cycles (``CoCiP'') and can allow for the rapid simulation of contrail cirrus RF over a wide range of meteorological conditions and for a given size-dependent habit mixture. Ambient clouds are shown to have large local impact on the net RF of contrails. Net RF of contrails may both increase and decrease and even change sign in the presence of higher-level cirrus, depending on solar zenith angle.},
  langid = {english}
}

@inproceedings{schumannPotentialReduceClimate2011,
  title = {Potential to Reduce the Climate Impact of Aviation by Flight Level Changes},
  booktitle = {3rd {{AIAA Atmospheric Space Environments Conference}}},
  author = {Schumann, Ulrich and Graf, Kaspar and Mannstein, Hermann},
  year = {2011},
  month = jun,
  publisher = {{American Institute of Aeronautics and Astronautics}},
  address = {{Honolulu, Hawaii}},
  doi = {10.2514/6.2011-3376},
  urldate = {2022-02-21},
  isbn = {978-1-62410-143-4},
  langid = {english}
}

@incollection{schumannPotentialReduceClimate2011a,
  title = {Potential to Reduce the Climate Impact of Aviation by Flight Level Changes},
  booktitle = {3rd {{AIAA Atmospheric Space Environments Conference}}},
  author = {Schumann, Ulrich and Graf, Kaspar and Mannstein, Hermann},
  year = {2011},
  month = jun,
  series = {Fluid {{Dynamics}} and {{Co-located Conferences}}},
  publisher = {{American Institute of Aeronautics and Astronautics}},
  doi = {10.2514/6.2011-3376},
  urldate = {2023-04-16},
  keywords = {Aviation,Base of Aircraft Data,Contrails,Cruise Altitude,Earth,Earth Atmosphere,Fuel Consumption,Greenhouse Effect,Numerical Weather Prediction,Optical Depth}
}

@article{schumannPropertiesIndividualContrails2017,
  title = {Properties of Individual Contrails: A Compilation of Observations and Some Comparisons},
  shorttitle = {Properties of Individual Contrails},
  author = {Schumann, Ulrich and Baumann, Robert and Baumgardner, Darrel and Bedka, Sarah T. and Duda, David P. and Freudenthaler, Volker and Gayet, Jean-Francois and Heymsfield, Andrew J. and Minnis, Patrick and Quante, Markus and Raschke, Ehrhard and Schlager, Hans and {V{\'a}zquez-Navarro}, Margarita and Voigt, Christiane and Wang, Zhien},
  year = {2017},
  month = jan,
  journal = {Atmospheric Chemistry and Physics},
  volume = {17},
  number = {1},
  pages = {403--438},
  issn = {1680-7324},
  doi = {10.5194/acp-17-403-2017},
  urldate = {2022-02-19},
  abstract = {Abstract. Mean properties of individual contrails are characterized for a wide range of jet aircraft as a function of age during their life cycle from seconds to 11.5\,h (7.4\textendash 18.7\,km altitude, -88 to -31\,\textdegree C ambient temperature), based on a compilation of about 230 previous in situ and remote sensing measurements. The airborne, satellite, and ground-based observations encompass exhaust contrails from jet aircraft from 1972 onwards, as well as a few older data for propeller aircraft. The contrails are characterized by mean ice particle sizes and concentrations, extinction, ice water content, optical depth, geometrical depth, and contrail width. Integral contrail properties include the cross-section area and total number of ice particles, total ice water content, and total extinction (area integral of extinction) per contrail length. When known, the contrail-causing aircraft and ambient conditions are characterized. The individual datasets are briefly described, including a few new analyses performed for this study, and compiled together to form a contrail library (COLI). The data are compared with results of the Contrail Cirrus Prediction (CoCiP) model. The observations confirm that the number of ice particles in contrails is controlled by the engine exhaust and the formation process in the jet phase, with some particle losses in the wake vortex phase, followed later by weak decreases with time. Contrail cross sections grow more quickly than expected from exhaust dilution. The cross-section-integrated extinction follows an algebraic approximation. The ratio of volume to effective mean radius decreases with time. The ice water content increases with increasing temperature, similar to non-contrail cirrus, while the equivalent relative humidity over ice saturation of the contrail ice mass increases at lower temperatures in the data. Several contrails were observed in warm air above the Schmidt\textendash Appleman threshold temperature. The emission index of ice particles, i.e., the number of ice particles formed in the young contrail per burnt fuel mass, is estimated from the measured concentrations for estimated dilution; maximum values exceed 1015\,kg-1. The dependence of the data on the observation methods is discussed. We find no obvious indication for significant contributions from spurious particles resulting from shattering of ice crystals on the microphysical probes.},
  langid = {english}
}

@inproceedings{schumannRadiativeHeatingContrail2010,
  title = {Radiative Heating in Contrail Cirrus},
  booktitle = {Geophysical {{Research Abstracts}}},
  author = {Schumann, Ulrich and Mayer, Bernhard and Hamann, Ulrich and Graf, Kaspar},
  year = {2010},
  volume = {12},
  pages = {1--2},
  publisher = {{EGU}},
  address = {{Wien}},
  urldate = {2023-03-24},
  abstract = {We developed an effective model (within our contrail cirrus prediction model, CoCiP) which computes the radiative heating rate in both the longwave and shortwave spectral ranges. The model parameterizes the impact of radiative heating on turbulent mixing and sublimation of ice particles in a thin cirrus layer.},
  langid = {english}
}

@article{sonntag1994,
  title = {Advancements in the Field of Hygrometry},
  author = {Sonntag, D.},
  year = {1994},
  month = may,
  journal = {Meteorologische Zeitschrift},
  volume = {3},
  number = {2},
  pages = {51--66},
  publisher = {{Schweizerbart Science Publishers}},
  address = {{Stuttgart, Germany}},
  doi = {10.1127/metz/3/1994/51}
}

@article{spichtingerModellingCirrusClouds2009,
  title = {Modelling of Cirrus Clouds \textendash{} {{Part}} 1a: {{Model}} Description and Validation},
  shorttitle = {Modelling of Cirrus Clouds \textendash{} {{Part}} 1a},
  author = {Spichtinger, P. and Gierens, K. M.},
  year = {2009},
  month = jan,
  journal = {Atmospheric Chemistry and Physics},
  volume = {9},
  number = {2},
  pages = {685--706},
  issn = {1680-7324},
  doi = {10.5194/acp-9-685-2009},
  urldate = {2022-07-26},
  abstract = {A double-moment bulk microphysics scheme for modelling cirrus clouds including explicit impact of aerosols on different types of nucleation mechanism is described. Process rates are formulated in terms of generalised moments of the underlying a priori size distributions in order to allow simple switching between various distribution types. The scheme has been implemented into a simple box model and into the anelastic non-hydrostatic model EULAG. The new microphysics is validated against simulations with detailed microphysics for idealised process studies and for a well documented case of arctic cirrostratus. Additionally, the formation of ice crystals with realistic background aerosol concentration is modelled and the effect of ambient pressure on homogeneous nucleation is investigated in the box model.},
  langid = {english}
}

@article{stettlerAirQualityPublic2011,
  title = {Air Quality and Public Health Impacts of {{UK}} Airports. {{Part I}}: {{Emissions}}},
  shorttitle = {Air Quality and Public Health Impacts of {{UK}} Airports. {{Part I}}},
  author = {Stettler, M. E. J. and Eastham, S. and Barrett, S. R. H.},
  year = {2011},
  month = oct,
  journal = {Atmospheric Environment},
  volume = {45},
  number = {31},
  pages = {5415--5424},
  issn = {1352-2310},
  doi = {10.1016/j.atmosenv.2011.07.012},
  urldate = {2023-03-24},
  abstract = {The potential adverse human health and climate impacts of emissions from UK airports have become a significant political issue, yet the emissions, air quality impacts and health impacts attributable to UK airports remain largely unstudied. We produce an inventory of UK airport emissions \textendash{} including aircraft landing and takeoff (LTO) operations and airside support equipment \textendash{} with uncertainties quantified. The airports studied account for more than 95\% of UK air passengers in 2005. We estimate that in 2005, UK airports emitted 10.2~Gg [-23 to~+29\%] of NOx, 0.73~Gg [-29 to~+32\%] of SO2, 11.7~Gg [-42 to~+77\%] of CO, 1.8~Gg [-59 to~+155\%] of HC, 2.4~Tg [-13 to~+12\%] of CO2, and 0.31~Gg [-36 to~+45\%] of PM2.5. This translates to 2.5~Tg [-12 to~+12\%] CO2-eq using Global Warming Potentials for a 100-year time horizon. Uncertainty estimates were based on analysis of data from aircraft emissions measurement campaigns and analyses of aircraft operations. The First-Order Approximation (FOA3) \textendash{} currently the standard approach used to estimate particulate matter emissions from aircraft \textendash{} is compared to measurements and it is shown that there are discrepancies greater than an order of magnitude for 40\% of cases for both organic carbon and black carbon emissions indices. Modified methods to approximate organic carbon emissions, arising from incomplete combustion and lubrication oil, and black carbon are proposed. These alterations lead to factor 8 and a 44\% increase in the annual emissions estimates of black and organic carbon particulate matter, respectively, leading to a factor 3.4 increase in total PM2.5 emissions compared to the current FOA3 methodology. Our~estimates of emissions are used in Part II to quantify the air quality and health impacts of UK airports, to assess mitigation options, and to estimate the impacts of a potential London airport expansion.},
  langid = {english},
  keywords = {Air quality,Airport,Aviation,Emissions,Particulate matter}
}

@article{stettlerGlobalCivilAviation2013,
  title = {Global {{Civil Aviation Black Carbon Emissions}}},
  author = {Stettler, Marc E. J. and Boies, Adam M. and Petzold, Andreas and Barrett, Steven R. H.},
  year = {2013},
  month = sep,
  journal = {Environmental Science \& Technology},
  volume = {47},
  number = {18},
  pages = {10397--10404},
  publisher = {{American Chemical Society}},
  issn = {0013-936X},
  doi = {10.1021/es401356v},
  urldate = {2022-03-21},
  abstract = {Aircraft black carbon (BC) emissions contribute to climate forcing, but few estimates of BC emitted by aircraft at cruise exist. For the majority of aircraft engines the only BC-related measurement available is smoke number (SN)\textemdash a filter based optical method designed to measure near-ground plume visibility, not mass. While the first order approximation (FOA3) technique has been developed to estimate BC mass emissions normalized by fuel burn [EI(BC)] from SN, it is shown that it underestimates EI(BC) by {$>$}90\% in 35\% of directly measured cases (R2 = -0.10). As there are no plans to measure BC emissions from all existing certified engines\textemdash which will be in service for several decades\textemdash it is necessary to estimate EI(BC) for existing aircraft on the ground and at cruise. An alternative method, called FOX, that is independent of the SN is developed to estimate BC emissions. Estimates of EI(BC) at ground level are significantly improved (R2 = 0.68), whereas estimates at cruise are within 30\% of measurements. Implementing this approach for global civil aviation estimated aircraft BC emissions are revised upward by a factor of {$\sim$}3. Direct radiative forcing (RF) due to aviation BC emissions is estimated to be {$\sim$}9.5 mW/m2, equivalent to {$\sim$}1/3 of the current RF due to aviation CO2 emissions.}
}

@article{sunParametrizationEffectiveSizes1999,
  title = {Parametrization of Effective Sizes of Cirrus-Cloud Particles and Its Verification against Observations: {{RADIATIVE FOR CING AND CLIMATE SENSITIVITY}}},
  shorttitle = {Parametrization of Effective Sizes of Cirrus-Cloud Particles and Its Verification against Observations},
  author = {Sun, Zhian and Rikus, Lawrie},
  year = {1999},
  month = oct,
  journal = {Quarterly Journal of the Royal Meteorological Society},
  volume = {125},
  number = {560},
  pages = {3037--3055},
  issn = {00359009},
  doi = {10.1002/qj.49712556012},
  urldate = {2022-03-23},
  abstract = {A simplified parametrization of effective sizes of cirrus-cloud particles is developed in terms of the ice-water content and the cloud temperature based on some earlier studies. The effective particle sizes of the cirrus clouds determined using the simplified parametrization are compared with the results determined from observations. The results are generally encouraging.},
  langid = {english}
}

@article{teohAviationContrailClimate2022,
  title = {Aviation Contrail Climate Effects in the {{North Atlantic}} from 2016 to 2021},
  author = {Teoh, Roger and Schumann, Ulrich and Gryspeerdt, Edward and Shapiro, Marc and Molloy, Jarlath and Koudis, George and Voigt, Christiane and Stettler, Marc E. J.},
  year = {2022},
  month = aug,
  journal = {Atmospheric Chemistry and Physics},
  volume = {22},
  number = {16},
  pages = {10919--10935},
  publisher = {{Copernicus GmbH}},
  issn = {1680-7316},
  doi = {10.5194/acp-22-10919-2022},
  urldate = {2023-03-06},
  abstract = {Around 5 \% of anthropogenic radiative forcing (RF) is attributed to aviation CO2 and non-CO2 impacts. This paper quantifies aviation emissions and contrail climate forcing in the North Atlantic, one of the world's busiest air traffic corridors, over 5 years. Between 2016 and 2019, growth in CO2 (+3.13 \% yr-1) and nitrogen oxide emissions (+4.5 \% yr-1) outpaced increases in flight distance (+3.05 \% yr-1). Over the same period, the annual mean contrail cirrus net RF (204\textendash 280 mW m-2) showed significant inter-annual variability caused by variations in meteorology. Responses to COVID-19 caused significant reductions in flight distance travelled (-66 \%), CO2 emissions (-71 \%) and the contrail net RF (-66 \%) compared with the prior 1-year period. Around 12 \% of all flights in this region cause 80 \% of the annual contrail energy forcing, and the factors associated with strongly warming/cooling contrails include seasonal changes in meteorology and radiation, time of day, background cloud fields, and engine-specific non-volatile particulate matter (nvPM) emissions. Strongly warming contrails in this region are generally formed in wintertime, close to the tropopause, between 15:00 and 04:00 UTC, and above low-level clouds. The most strongly cooling contrails occur in the spring, in the upper troposphere, between 06:00 and 15:00 UTC, and without lower-level clouds. Uncertainty in the contrail cirrus net RF (216\textendash 238 mW m-2) arising from meteorology in 2019 is smaller than the inter-annual variability. The contrail RF estimates are most sensitive to the humidity fields, followed by nvPM emissions and aircraft mass assumptions. This longitudinal evaluation of aviation contrail impacts contributes a quantified understanding of inter-annual variability and informs strategies for contrail mitigation.},
  langid = {english}
}

@article{teohMethodologyRelateBlack2019,
  title = {A Methodology to Relate Black Carbon Particle Number and Mass Emissions},
  author = {Teoh, Roger and Stettler, Marc E.J. and Majumdar, Arnab and Schumann, Ulrich and Graves, Brian and Boies, Adam M.},
  year = {2019},
  month = jun,
  journal = {Journal of Aerosol Science},
  volume = {132},
  pages = {44--59},
  issn = {00218502},
  doi = {10.1016/j.jaerosci.2019.03.006},
  urldate = {2020-12-21},
  abstract = {Black carbon (BC) particle number (PN) emissions from various sources contribute to the deterioration of air quality, adverse health effects, and anthropogenic climate change. This paper critically reviews different fractal aggregate theories to develop a new methodology that relates BC PN and mass concentrations (or emissions factors). The new methodology, named as the fractal aggregate (FA) model is validated with measurements from three different BC emission sources: an internal combustion engine, a soot generator, and two aircraft gas turbine engines at ground and cruise conditions. Validation results of the FA model show that R2 values range from 0.44 to 0.95, while the Normalised Mean Bias is between -27.7\% and +26.6\%. The model estimates for aircraft gas turbines represent a significant improvement compared to previous methodologies used to estimate aviation BC PN emissions, which relied on simplified assumptions. Uncertainty and sensitivity analyses show that the FA model estimates have an asymmetrical uncertainty bound (-54\%, +103\%) at a 95\% confidence interval for aircraft gas turbine engines and are most sensitive to uncertainties in the geometric standard deviation of the BC particle size distribution. Given the improved performance in estimating BC PN emissions from various sources, we recommend the implementation of the FA model in future health and climate assessments, where the impacts of PN are significant.},
  langid = {english}
}

@article{teohMitigatingClimateForcing2020,
  title = {Mitigating the {{Climate Forcing}} of {{Aircraft Contrails}} by {{Small-Scale Diversions}} and {{Technology Adoption}}},
  author = {Teoh, Roger and Schumann, Ulrich and Majumdar, Arnab and Stettler, Marc E. J.},
  year = {2020},
  month = mar,
  journal = {Environmental Science \& Technology},
  volume = {54},
  number = {5},
  pages = {2941--2950},
  issn = {0013-936X, 1520-5851},
  doi = {10.1021/acs.est.9b05608},
  urldate = {2020-12-16},
  abstract = {The climate forcing of contrails and induced-cirrus cloudiness is thought to be comparable to the cumulative impacts of aviation CO2 emissions. This paper estimates the impact of aviation contrails on climate forcing for flight track data in Japanese airspace and propagates uncertainties arising from meteorology and aircraft black carbon (BC) particle number emissions. Uncertainties in the contrail age, coverage, optical properties, radiative forcing, and energy forcing (EF) from individual flights can be 2 orders of magnitude larger than the fleet-average values. Only 2.2\% [2.0, 2.5\%] of flights contribute to 80\% of the contrail EF in this region. A small-scale strategy of selectively diverting 1.7\% of the fleet could reduce the contrail EF by up to 59.3\% [52.4, 65.6\%], with only a 0.014\% [0.010, 0.017\%] increase in total fuel consumption and CO2 emissions. A low-risk strategy of diverting flights only if there is no fuel penalty, thereby avoiding additional long-lived CO2 emissions, would reduce contrail EF by 20.0\% [17.4, 23.0\%]. In the longer term, widespread use of new engine combustor technology, which reduces BC particle emissions, could achieve a 68.8\% [45.2, 82.1\%] reduction in the contrail EF. A combination of both interventions could reduce the contrail EF by 91.8\% [88.6, 95.8\%].},
  langid = {english}
}

@article{teohTargetedUseSustainable2022,
  title = {Targeted {{Use}} of {{Sustainable Aviation Fuel}} to {{Maximize Climate Benefits}}},
  author = {Teoh, Roger and Schumann, Ulrich and Voigt, Christiane and Schripp, Tobias and Shapiro, Marc and Engberg, Zebediah and Molloy, Jarlath and Koudis, George and Stettler, Marc E. J.},
  year = {2022},
  month = nov,
  journal = {Environmental Science \& Technology},
  publisher = {{American Chemical Society}},
  issn = {0013-936X},
  doi = {10.1021/acs.est.2c05781},
  urldate = {2022-11-18},
  abstract = {Sustainable aviation fuel (SAF) can reduce aviation's CO2 and non-CO2 impacts. We quantify the change in contrail properties and climate forcing in the North Atlantic resulting from different blending ratios of SAF and demonstrate that intelligently allocating the limited SAF supply could multiply its overall climate benefit by factors of 9\textendash 15. A fleetwide adoption of 100\% SAF increases contrail occurrence (+5\%), but lower nonvolatile particle emissions (-52\%) reduce the annual mean contrail net radiative forcing (-44\%), adding to climate gains from reduced life cycle CO2 emissions. However, in the short term, SAF supply will be constrained. SAF blended at a 1\% ratio and uniformly distributed to all transatlantic flights would reduce both the annual contrail energy forcing (EFcontrail) and the total energy forcing (EFtotal, contrails + change in CO2 life cycle emissions) by {$\sim$}0.6\%. Instead, targeting the same quantity of SAF at a 50\% blend ratio to {$\sim$}2\% of flights responsible for the most highly warming contrails reduces EFcontrail and EFtotal by {$\sim$}10 and {$\sim$}6\%, respectively. Acknowledging forecasting uncertainties, SAF blended at lower ratios (10\%) and distributed to more flights ({$\sim$}9\%) still reduces EFcontrail ({$\sim$}5\%) and EFtotal ({$\sim$}3\%). Both strategies deploy SAF on flights with engine particle emissions exceeding 1012 m\textendash 1, at night-time, and in winter.}
}

@misc{uosolarradiationmonitoringlaboratoryUOSRMLSolar2022,
  title = {{{UO SRML}}: {{Solar}} Radiation Basics},
  author = {UO Solar Radiation Monitoring Laboratory},
  year = {2022},
  urldate = {2023-02-15},
  howpublished = {http://solardat.uoregon.edu/SolarRadiationBasics.html}
}

@article{voigtInsituObservationsYoung2010,
  title = {In-Situ Observations of Young Contrails \textendash{} Overview and Selected Results from the {{CONCERT}} Campaign},
  author = {Voigt, C. and Schumann, U. and Jurkat, T. and Sch{\"a}uble, D. and Schlager, H. and Petzold, A. and Gayet, J.-F. and Kr{\"a}mer, M. and Schneider, J. and Borrmann, S. and Schmale, J. and Jessberger, P. and Hamburger, T. and Lichtenstern, M. and Scheibe, M. and Gourbeyre, C. and Meyer, J. and K{\"u}bbeler, M. and Frey, W. and Kalesse, H. and Butler, T. and Lawrence, M. G. and Holz{\"a}pfel, F. and Arnold, F. and Wendisch, M. and D{\"o}pelheuer, A. and Gottschaldt, K. and Baumann, R. and Z{\"o}ger, M. and S{\"o}lch, I. and Rautenhaus, M. and D{\"o}rnbrack, A.},
  year = {2010},
  month = sep,
  journal = {Atmospheric Chemistry and Physics},
  volume = {10},
  number = {18},
  pages = {9039--9056},
  publisher = {{Copernicus GmbH}},
  issn = {1680-7316},
  doi = {10.5194/acp-10-9039-2010},
  urldate = {2023-04-16},
  abstract = {Lineshaped contrails were detected with the research aircraft Falcon during the CONCERT \textendash{} CONtrail and Cirrus ExpeRimenT \textendash{} campaign in October/November 2008. The Falcon was equipped with a set of instruments to measure the particle size distribution, shape, extinction and chemical composition as well as trace gas mixing ratios of sulfur dioxide (SO2), reactive nitrogen and halogen species (NO, NOy, HNO3, HONO, HCl), ozone (O3) and carbon monoxide (CO). During 12 mission flights over Europe, numerous contrails, cirrus clouds and a volcanic aerosol layer were probed at altitudes between 8.5 and 11.6 km and at temperatures above 213 K. 22 contrails from 11 different aircraft were observed near and below ice saturation. The observed NO mixing ratios, ice crystal and soot number densities are compared to a process based contrail model. On 19 November 2008 the contrail from a CRJ-2 aircraft was penetrated in 10.1 km altitude at a temperature of 221 K. The contrail had mean ice crystal number densities of 125 cm-3 with effective radii reff of 2.6 {$\mu$}m. The presence of particles with r{$>$}50 {$\mu$}m in the less than 2 min old contrail suggests that natural cirrus crystals were entrained in the contrail. Mean HONO/NO (HONO/NOy) ratios of 0.037 (0.024) and the fuel sulfur conversion efficiency to H2SO4 (\&epsilon;S{$\downarrow$}) of 2.9 \% observed in the CRJ-2 contrail are in the range of previous measurements in the gaseous aircraft exhaust. On 31 October 2010 aviation NO emissions could have contributed by more than 40\% to the regional scale NO levels in the mid-latitude lowest stratosphere. The CONCERT observations help to better quantify the climate impact from contrails and will be used to investigate the chemical processing of trace gases on contrails.},
  langid = {english}
}

@article{wasiukAircraftPerformanceModel2015,
  title = {An Aircraft Performance Model Implementation for the Estimation of Global and Regional Commercial Aviation Fuel Burn and Emissions},
  author = {Wasiuk, D. K. and Lowenberg, M. H. and Shallcross, D. E.},
  year = {2015},
  month = mar,
  journal = {Transportation Research Part D: Transport and Environment},
  volume = {35},
  pages = {142--159},
  issn = {1361-9209},
  doi = {10.1016/j.trd.2014.11.022},
  urldate = {2022-03-21},
  abstract = {Estimates of global aviation fuel burn and emissions are currently nearly 10years out of date. Here, the development of the Aircraft Performance Model Implementation (APMI) software which is used to update global commercial aviation fuel burn and emissions estimates is described. The results from APMI are compared with published estimates obtained using the US Federal Aviation Administration's System for Assessing Aviation's Global Emissions (SAGE) for the year 2006. The number of global departures modelled with the APMI software is 8\% lower compared with SAGE and reflects the difference between their commercial air traffic statistics data sources. The mission fuel burn, CO2 and H2O estimates from APMI are approximately 20\% lower than those predicted by SAGE for 2006 while the estimate for the total global aircraft SOx emissions is approximately 40\% lower. The estimates for the emissions of CO, HC and NOx are 10\%, 140\% and 30\% higher than those predicted by SAGE respectively. The reasons for these differences are discussed in detail.},
  langid = {english},
  keywords = {Global aviation emissions,Global aviation fuel burn}
}

@misc{wikipediacontributorsAzimuth2023,
  title = {Azimuth},
  author = {{Wikipedia contributors}},
  year = {2023},
  journal = {Wikipedia},
  urldate = {2023-04-05},
  abstract = {An azimuth ( (listen); from Arabic: اَلسُّمُوت, romanized: as-sum\=ut, lit.\,'the directions') is an angular measurement in a spherical coordinate system. More specifically, it is the horizontal angle from a cardinal direction, most commonly north.  Mathematically, the relative position vector from an observer (origin) to a point of interest is projected perpendicularly onto a reference plane (the horizontal plane); the angle between the projected vector and a reference vector on the reference plane is called the azimuth. When used as a celestial coordinate, the azimuth is the horizontal direction of a star or other astronomical object in the sky. The star is the point of interest, the reference plane is the local area (e.g. a circular area with a 5 km radius at sea level) around an observer on Earth's surface, and the reference vector points to true north. The azimuth is the angle between the north vector and the star's vector on the horizontal plane.Azimuth is usually measured in degrees (\textdegree ). The concept is used in navigation, astronomy, engineering, mapping, mining, and ballistics.},
  copyright = {Creative Commons Attribution-ShareAlike License},
  howpublished = {https://en.wikipedia.org/w/index.php?title=Azimuth\&oldid=1131548993},
  langid = {english},
  annotation = {Page Version ID: 1131548993}
}

@misc{wikipediacontributorsBarometricFormula2023,
  title = {Barometric Formula},
  author = {{Wikipedia contributors}},
  year = {2023},
  journal = {Wikipedia},
  urldate = {2023-03-15},
  abstract = {The barometric formula is a formula used to model how the pressure (or density) of the air changes with altitude.},
  copyright = {Creative Commons Attribution-ShareAlike License},
  howpublished = {https://en.wikipedia.org/w/index.php?title=Barometric\_formula\&oldid=1144039200},
  langid = {english},
  annotation = {Page Version ID: 1144039200}
}

@misc{wikipediacontributorsInternationalStandardAtmosphere2023,
  title = {International {{Standard Atmosphere}}},
  author = {{Wikipedia contributors}},
  year = {2023},
  journal = {Wikipedia},
  urldate = {2023-03-15},
  abstract = {The International Standard Atmosphere (ISA) is a static atmospheric model of how the pressure, temperature, density, and viscosity of the Earth's atmosphere change over a wide range of altitudes or elevations. It has been established to provide a common reference for temperature and pressure and consists of tables of values at various altitudes, plus some formulas by which those values were derived. The International Organization for Standardization (ISO) publishes the ISA as an international standard, ISO 2533:1975. Other standards organizations, such as the International Civil Aviation Organization (ICAO) and the United States Government, publish extensions or subsets of the same atmospheric model under their own standards-making authority.},
  copyright = {Creative Commons Attribution-ShareAlike License},
  howpublished = {https://en.wikipedia.org/w/index.php?title=International\_Standard\_Atmosphere\&oldid=1143858065\#ICAO\_Standard\_Atmosphere},
  langid = {english},
  annotation = {Page Version ID: 1143858065}
}

@misc{wikipediacontributorsSolarZenithAngle2023,
  title = {Solar Zenith Angle},
  author = {{Wikipedia contributors}},
  year = {2023},
  journal = {Wikipedia},
  urldate = {2023-03-29},
  abstract = {The solar zenith angle is the zenith angle of the sun, i.e., the angle between the sun's rays and the vertical direction. It is the complement to the solar altitude or solar elevation, which is the altitude angle or elevation angle between the sun's rays and a horizontal plane. At solar noon, the zenith angle is at a minimum and is equal to latitude minus solar declination angle. This is the basis by which ancient mariners navigated the oceans.},
  copyright = {Creative Commons Attribution-ShareAlike License},
  howpublished = {https://en.wikipedia.org/w/index.php?title=Solar\_zenith\_angle\&oldid=1141660912},
  langid = {english},
  annotation = {Page Version ID: 1141660912}
}

@article{wilkersonAnalysisEmissionData2010,
  title = {Analysis of Emission Data from Global Commercial Aviation: 2004 and 2006},
  shorttitle = {Analysis of Emission Data from Global Commercial Aviation},
  author = {Wilkerson, J. T. and Jacobson, M. Z. and Malwitz, A. and Balasubramanian, S. and Wayson, R. and Fleming, G. and Naiman, A. D. and Lele, S. K.},
  year = {2010},
  month = jul,
  journal = {Atmospheric Chemistry and Physics},
  volume = {10},
  number = {13},
  pages = {6391--6408},
  publisher = {{Copernicus GmbH}},
  issn = {1680-7316},
  doi = {10.5194/acp-10-6391-2010},
  urldate = {2022-03-21},
  abstract = {{$<$}p{$><$}strong class="journal-contentHeaderColor"{$>$}Abstract.{$<$}/strong{$>$} The global commercial aircraft fleet in 2006 flew 31.26 million flights, burned 188.20 million metric tons of fuel, and covered 38.68 billion kilometers. This activity emitted substantial amounts of fossil-fuel combustion products within the upper troposphere and lower stratosphere that affect atmospheric composition and climate. The emissions products, such as carbon monoxide, carbon dioxide, oxides of nitrogen, sulfur compounds, and particulate matter, are not emitted uniformly over the Earth, so understanding the temporal and spatial distributions is important for modeling aviation's climate impacts. Global commercial aircraft emission data for 2004 and 2006, provided by the Volpe National Transportation Systems Center, were computed using the Federal Aviation Administration's Aviation Environmental Design Tool (AEDT). Continuous improvement in methodologies, including changes in AEDT's horizontal track methodologies, and an increase in availability of data make some differences between the 2004 and 2006 inventories incomparable. Furthermore, the 2004 inventory contained a significant over-count due to an imperfect data merge and daylight savings error. As a result, the 2006 emissions inventory is considered more representative of actual flight activity. Here, we analyze both 2004 and 2006 emissions, focusing on the latter, and provide corrected totals for 2004. Analysis of 2006 flight data shows that 92.5\% of fuel was burned in the Northern Hemisphere, 69.0\% between 30N and 60N latitudes, and 74.6\% was burned above 7 km. This activity led to 162.25 Tg of carbon from CO\textsubscript{2} emitted globally in 2006, more than half over three regions: the United States (25.5\%), Europe (14.6), and East Asia (11.1). Despite receiving less than one percent of global emissions, the Arctic receives a uniformly dispersed concentration of emissions with 95.2\% released at altitude where they have longer residence time than surface emissions. Finally, 85.2\% of all flights by number in 2006 were short-haul missions, yet those flights were responsible for only 39.7\% of total carbon from CO\textsubscript{2}. The following is a summary of these data which illustrates the global and regional aviation emissions footprints for 2004 and 2006, and provides temporal and spatial distribution statistics.{$<$}/p{$>$}},
  langid = {english}
}
