What is OpenAirClim?

OpenAirClim is a model for simplified evaluation of the approximate chemistry-climate impact of air traffic emissions. The model represents the major responses of the atmosphere to emissions in terms of composition and climate change. Instead of applying time-consuming climate-chemistry models, a response model is developed and applied which reproduces the response of a climate-chemistry model without actually calculating ab initio all the physical and chemical effects. The responses are non-linear relations between localized emissions and Radiative Forcing and further climate indicators. These response surfaces are contained within look-up tables. OpenAirClim builds upon the previous AirClim framework. In comparison with AirClim, following new features are introduced:

  • Standardized formats for configuration file (user interface) and emission inventories (input) and program results (output)

  • Possibility of full 4D emission inventories (3D for several time steps)

  • Non-linear response functions for NOx including contribution approach (tagging) and dependency on background

  • Contrail formation also depending on fuels and overall efficiencies

  • Inclusion of different fuels

  • Choice of different CO2 response models

  • Choice of temperature models and sea-level rise

  • Uncertainty assessment and Robustness Metric based on Monte Carlo Simulations

  • Parametric scenarios as sensitivities, e.g. at post-processing level: climate optimized routings

Scientific Background

The impact of aviation on climate amounts to approximately 3.5% of the total anthropogenic climate warming [9]. A large part of the aviation’s impact arises from non-CO2 effects, especially contrails [1, 2] and nitrogen oxide emissions [12, 14]. Impact of non-CO2 effects depend in particular on the location and time of emissions [5, 10], hence a regional dependence of impacts exists. As impacts of individual non-CO2 effects show a different spatial dependence, the relationship between impacts and associated emissions can be best described in non-linear relationships, i.e. equations or algorithms based on look-up tables. Specifically, the climate impact of an aircraft depends on where (and when) an aircraft is operated. In addition, using different types of fuel generally changes the importance of the non-CO2 effects.

Layout

Overview of the OpenAirClim framework

Overview of the OpenAirClim framework

  • User interface for settings in the run control and outputs (grey)

  • Definition of background conditions, such as aviation scenarios, uncertainty ranges and aviation inventories (orange)

  • A link to a pre-processor for aviation inventories (blue)

  • Processor for a full 4D-emission inventory at multiple timesteps (magenta)

  • A framework for the application of non-linear response functions (red) to these emission inventories.

  • Response functions for CO2 and climate / temperature and sea-level changes

  • Parametric scenarios as sensitivities (yellow), e.g. at post-processing level: climate optimized routings

  • Output: Warnings, errors (log files), climate indicators and diagnostics (green), values of climate metrics and robustness metrics (grey)