FAA Unveils Contrails Research Roadmap
A Summary of Said Roadmap and the Research it Entails
The importance of researching aviation contrails is undeniable. Therefore, gaining a better grasp of their climate effects and how to navigate those effects has become a priority throughout the aviation industry. The current understanding is that persistent contrails have a warming impact on the climate, though the magnitude is unknown. This uncertainty is driving additional research – to enhance scientific understanding, improve operational strategies, develop mitigation techniques, design better prediction capabilities, and implement governance policies. Thus far, Europe has led the way in both research and policy-making, with the European Commission’s EU Emissions Trading System MRV framework being the primary example.
The United States, equally wary of the influence contrails have on the environment, has formed an alliance of governmental agencies to address the knowledge gaps in contrail research and inform future policy decisions. This coalition is comprised of the Federal Aviation Administration (FAA), the National Aeronautics and Space Administration (NASA), and the National Oceanic and Atmospheric Administration (NOAA). These agencies have collaborated to create the Contrails Research Roadmap, a regularly updated document designed to identify high-level targets and research requirements.
Fields of Research
Within the broader framework of the roadmap, the research program will focus on four principal areas to inform prospective solutions for contrail management and future research activities:
1) Atmospheric Science
2) Weather Prediction
3) Cruise Emissions
4) Operational Management.
Each section describes specific research needs and milestones necessary “to achieve the long-term vision of effective, routine, system-wide contrail management that incorporates climate impacts and economic tradeoffs by 2050.” (pg. 3) Contrail management requires an in-depth understanding of atmospheric chemistry and physics, weather prediction, aircraft emissions, and operational management.
Building this knowledge base and developing effective mitigation solutions will require years to decades of research and involve further close collaboration between government agencies and the global aviation industry. Now, let’s dig deeper into these four fields of research.
Atmospheric Science – a complex field of study dealing with how aviation emissions interact with the Earth’s atmosphere and the radiative forcing that ensues. Contrail formation is dependent upon atmospheric conditions, so improving the understanding of the micro- and macrophysical processes that lead to persistent contrails and how they interact with natural cirrus is imperative to developing robust sensing tools and prediction models. The roadmap outlines a few key research goals into atmospheric science:
Characterization of atmospheric temperature, water vapor, and particles relevant for contrail cirrus and natural cirrus clouds – to understand the atmospheric features critical in the formation of contrails as well as the interaction of aircraft aerosol emissions with natural cirrus clouds.
Improved understanding of contrail cirrus persistence and evolution over time – to study the full life cycle of contrails as they become persistent contrail cirrus with satellite and ground-based sensors.
Improved predictability of the environmental impact from individual flights – to predict the factors that contribute to a flight’s warming impact whether on a per-flight or regional basis.
Linking ground-based and in-flight emissions measurements and understanding how emissions at cruise determine contrail microphysical properties – to consider and study the different impacts that flight emissions would have at altitude and the alternative particles, such as oil vapor, which may play a role in contrail formation.
Improved understanding of contrail effective radiative forcing and climate impact – to develop a more precise understanding of contrail climate effects and reduce the uncertainties surrounding effective radiative forcing for enhanced contrail management efforts.
Satellite observations for contrails –to improve contrail detection and validation and research the future of space-based remote sensing with advanced satellite resolution and retrieval algorithms.
Understanding the atmospheric impacts and trade space of non-CO2 versus CO2 emissions – to predict and clarify the impacts of an individual contrail against those of other aviation emissions such as CO2, NOx, etc. (pgs. 8-10)
Weather Prediction – another area vital to, not just the understanding and predicting of contrail formation, but the streamlining of planning for all flight routes. A better understanding of atmospheric variables that influence contrail formation, such as temperature, wind speed, humidity, and background radiation, will improve weather prediction models. This, in turn with new technologies, increased in situ data, enhanced remote-sensing, and more satellite observations will significantly reduce uncertainties, generate more informed in-flight routing decisions, and allow for “real-time management of contrails to reduce their environmental impact.” (pg. 10) The roadmap provides five objectives for weather prediction research:
Improved accuracy and timeliness of temperature and relative humidity at altitude – to assimilate numerical weather prediction models with thermal and moisture observations to develop better models of contrail formation and evolution.
Robust understanding of uncertainty and forecast levels of confidence – to characterize the degrees of uncertainty regarding forecasting to understand where improvements are needed and enhance mitigation strategies.
Improved characterization of background atmospheric radiation environment – to quantify the warming and cooling effects of contrails while increasing the accuracy of the predicted formation and lifetime of contrails.
Weather satellite launch and model prediction improvements – to demonstrate how best to utilize satellite observations to enhance estimates of atmospheric temperature and relative humidity profiles.
Aircraft atmospheric sensor technology development and implementation – to improve humidity and temperature sensors for better real-time contrail detection as well as the forecasting of regions which may induce persistent contrails. (pgs. 10-11)
Cruise Emissions – remnants of hot exhaust emissions produced by aircraft engines burning at high altitudes become cloud condensation nuclei and lead to the formation of contrails in cold regions with high humidity. Carbon dioxide (CO2), water vapor, sulfur oxides (SOx), nitrogen oxides (NOx), soot, and non-volatile particulate matter (nvPM) are the main emissions of conventional jet fuel which become cloud nuclei, condensing to create contrails. Research into engine technologies, alternative fuels, and exhaust measurements will be critical to decrease emissions and mitigate contrails. The targets mentioned in the roadmap include:
Understanding emissions characteristic variations from current propulsion systems with current fuels – to determine how pollutants at cruise altitude lead to the development of warming contrails by studying conventional and alternative fuels.
Explore and characterize future fuel emissions and impacts – to assess the potential of alternative propulsion systems such as hydrogen, liquid natural gas, and cryogenic fuels.
Advance and enable technologies that reduce the formation of persistent warming contrails – to discover and prioritize the production of emissions technologies which reduce the formation of persistent contrails by harnessing partnerships across the sector. (pg. 12)
Operational Management – the art of making adjustments pre- and mid-flight to avoid the formation of persistent contrails. Contrail avoidance, the colloquial term for operational management, is no easy task and requires, according to the roadmap, “decision support capabilities, concepts of operation (CONOPS), methods for verification of effectiveness, and protocols/mechanisms for contrail information connectivity across aviation systems.” (pg. 12) The roadmap highlights four research aims necessary to achieve effective and efficient contrail management:
Development of prototype decision support capabilities and initial CONOPS for contrail operational management – to engage operational stakeholders to evaluate plausible CONOPS and future operational measures to enhance the efficiency of contrail management methods and the systems required to make it a reality.
Test/demonstration of decision support capabilities and CONOPS and iterative refinement – to fine-tune the tools and protocols needed for contrail management through testing and identifying areas which require further research and modeling.
Large-scale test/demonstration of regionally integrated contrail management capability – to establish flight trials through large swathes of air space over an extended period of time run by a team from across the aviation industry to engage and understand the full scope of the process.
Full connectivity of contrail operational management information across relevant aviation systems and stakeholders – to link relevant contrail information to flight planning practices to ensure that all relevant operational personnel can be part of the implementation of contrail management by establishing protocols, safety plans, and training material. (pg. 12-13)
Expectations and Outcomes
The practices and processes highlighted in this roadmap can identify the near- and long-term challenges and opportunities in contrail management. It is a statement of intent from the FAA, NASA, and NOAA to take the required steps to eliminate the scientific uncertainties which prevent progress, while engaging in forward-thinking measures to develop a sustainable system for contrail research and action. Many of the outlined research activities intersect and interact to establish a broader understanding and build a more robust approach to the study of persistent warming contrails.
The vision for these efforts is to implement effective, routine, system-wide contrail management by 2050. This vision includes prospective tradeoffs and climate impacts while anticipating shifts in goals and procedures as more information is learned along the way. Earlier initiatives will enhance the development of tools and models which will ultimately support the more distant objective of scaled contrail management. The agencies involved will track the research, taking stock and addressing the roadmap where appropriate to ensure that is up-to-date with the relevant progress and latest scientific findings.
As the Contrails Research Roadmap is updated and the scientific understanding expands and evolves, Plane Sight News will update and evolve accordingly, so be sure to check in regularly.