Assessing Climate Impact of Contrails
Insights from Japan’s High-Density Airspace and Meteorological Conditions
Katsuhiro Sekine (University of Tokyo, Research Center for Advanced Science and Technology)
Junzi Sun (TU Delft - Aerospace Engineering)
Tomoki Hasegawa (University of Tokyo)
Eri Itoh (University of Tokyo)
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Abstract
Persistent contrails significantly contribute to aviation’s climate impact through radiative forcing effects. Japanese airspace, characterized by high traffic density, prevalent short-haul flights, and diverse meteorological conditions, exhibits unique contrail formation patterns requiring tailored mitigation strategies. However, approaches such as altitude adjustments for contrail avoidance may lead to air traffic concentration at specific altitudes, raising aviation safety concerns. Therefore, this study identifies high-impact regions in Japanese airspace where contrail mitigation strategies can be effectively applied. Using the CoCiP model, CARATS Open Data, and ERA5 reanalysis, the analysis highlights critical seasonal and geographical patterns of contrail formation. Based on CARATS Open Data from 2019, which includes 399,541 flights across en route and oceanic airspace, April to June emerge as peak periods for contrail energy forcing (EF), driven by stable, humid atmospheric conditions. High-EF hotspots in southwestern, central, and northern Japan align with dense air traffic routes, with 1.71% of flights accounting for 80% of total contrail EF. A strong correlation between contrail altitude and persistence underscores the effectiveness of altitude adjustments for mitigation. Targeted strategies, such as nighttime altitude changes and interventions in high-EF sectors, could significantly reduce aviation’s climate impact. These findings establish a foundation for integrating contrail reduction measures into air traffic management systems in Japan, providing actionable insights for balancing climate benefits and operational safety.