Air traffic simulation in chemistry-climate model EMAC 2.41: AirTraf 1.0

Abstract

Abstract. Mobility is becoming more and more important to society and hence air transportation is expected to grow further over the next decades. Reducing anthropogenic climate impact from aviation emissions and building a climatefriendly air transportation system are required for a sustainable development of commercial aviation. A climate optimized routing, which avoids climate-sensitive regions by rerouting horizontally and vertically, is an important measure for climate impact reduction. The idea includes a number of different routing strategies (routing options) and shows a great potential for the reduction. To evaluate this, the impact of not only CO 2 but also non-CO 2 emissions must be considered. CO 2 is a long-lived gas, while non-CO 2 emissions are short-lived and are inhomogeneously distributed. This study introduces AirTraf (version 1.0) that performs global air traffic simulations, including effects of local weather conditions on the emissions. AirTraf was developed as a new submodel of the ECHAM5/MESSy Atmospheric Chemistry (EMAC) model. Air traffic information comprises Eurocontrol's Base of Aircraft Data (BADA Revision 3.9) and International Civil Aviation Organization (ICAO) engine performance data. Fuel use and emissions are calculated by the total energy model based on the BADA methodology and Deutsches Zentrum für Luft-und Raumfahrt (DLR) fuel flow method. The flight trajectory optimization is performed by a genetic algorithm (GA) with respect to a selected routing option. In the model development phase, benchmark tests were performed for the great circle and flight time routing options.The first test showed that the great circle calculations were accurate to −0.004 %, compared to those calculated by the Movable Type script. The second test showed that the optimal solution found by the algorithm sufficiently converged to the theoretical true-optimal solution. The difference in flight time between the two solutions is less than 0.01 %. The dependence of the optimal solutions on the initial set of solutions (called population) was analyzed and the influence was small (around 0.01 %). The trade-off between the accuracy of GA optimizations and computational costs is clarified and the appropriate population and generation (one iteration of GA) sizing is discussed. The results showed that a large reduction in the number of function evaluations of around 90 % can be achieved with only a small decrease in the accuracy of less than 0.1 %. Finally, AirTraf simulations are demonstrated with the great circle and the flight time routing options for a typical winter day. The 103 trans-Atlantic flight plans were used, assuming an Airbus A330-301 aircraft. The results confirmed that AirTraf simulates the air traffic properly for the two routing options. In addition, the GA successfully found the time-optimal flight trajectories for the 103 airport pairs, taking local weather conditions into account. The consistency check for the AirTraf simulations confirmed that calculated flight time, fuel consumption, NO ...

Mitigating the Climate Impact from Aviation: Achievements and Results of the DLR WeCare Project

“…The results show that the flights in the time-optimal case are spread over a larger area than in the great circle case. The total amount of fuel use decreases by −5.4% for the time-optimal case [73]. The difference in fuel use between the two routing options is clearly revealed and the options are directly assessed.…”

“…Starting from an optimization that uses optimal wind routes and avoids aviation obstacles like volcanic ash cloud regions, the optimization process is improved to calculate climate-optimal routes. AirTraf (for a complete description see [73]) was developed as a verification platform for climate optimized routing strategies. AirTraf is a new submodel of the EMAC model ( [47] see also Section 2.2) to simulate global air traffic (online) with respect to a selected routing strategy (routing option), such as optimal for wind, fuel, cost or climate, based on climate impact predictors.…”

A Concept for Multi-Criteria Environmental Assessment of Aircraft Trajectories

“…AirTraf is a module which has been integrated in a global climate-chemistry model working interactively during atmospheric calculations. AirTraf (version 1.0) [34,35]) was developed as a verification tool for climate optimised routing strategies by analysing individual routing options for given city pairs. AirTraf is a submodel of the ECHAM/MESSy Atmospheric Chemistry (EMAC) model [23,36] (ECHAM5 version 5.3.02, MESSy version 2.52) and simulates global air traffic (online) which is able to simulate aircraft trajectories under individual optimisation criteria.…”

Feasibility of climate-optimized air traffic routing for trans-Atlantic flights

“…To examine the relationship between changes in the climate impact and changes in costs for routing options, we apply a four step procedure. First, for each case study day, radiative forcings resulting from locally-confined unit emissions over the north Atlantic are calculated (section 2.2) by employing the detailed chemistry-climate model EMAC (Jöckel et al 2010(Jöckel et al , 2016 and then globally averaged. Second, the climate change induced by these emissions is calculated by applying emission metrics to these RF, resulting in climate-change functions (section 2.3, referred to in previous publications as climate-cost functions).…”

“…These algorithm-based CCFs and the climate impact reduction would need to be tested and verified. A feasible self-consistent way is to implement an air traffic simulator in an Earth-System Model and to optimize the climate reduction within this model (Yamashita et al 2016).…”