The prediction of Ice SuperSaturated Regions and persistent contrail formation using weather data and in-flight observations.

Aviation emissions contribute to climate change, one of the key contributors being contrail cirrus clouds. The importance of the impact is strongly dependent on their formation and persistence. A condensation trail - or contrail - is composed of ice crystals which form behind the aircraft engine exhaust at high altitudes when local weather conditions are favorable. The formation is also influenced by the engine technology and operating conditions, and by the fuel type. The contrail persists and evolves as long as it remains in an ice supersaturated region - or ISSR-, a local atmospheric air mass characterized by a low temperature and a humidity level that is saturated versus ice. Only persistent contrails are considered as having a climate effect. Weather forecast or reanalysis datasets were leveraged to understand if current data are sufficient to predict ISSRs and contrails, and to support the preparation of in-flight measurement campaigns. Statistics on ISSRs using multiple years of ERA5 ECMWF data will be presented for different months, and geographical areas. Results clearly help to identify geographical areas where the frequency of ISSRs is more important, as well as the seasonal, diurnal and vertical evolution of these frequencies. Using these results and incorporating information on annual meteorological changes, such as El Nio, a region and time of year was selected to conduct a contrail-related flight measurement campaign in Minnesota for two weeks of December 2023. During this period, NOAA GFS forecasts were used to identify ISSRs and plan aircraft flight paths. The forecast for a flight will be presented and compared to what was observed during this flight. The use of different resolutions to establish this forecast will also be discussed.