Five-day backwards trajectories at one minute resolution along the flight tracks of the Polar 6 research aircraft during HALO-(AC)3@en

The HALO-(AC)3 Arctic airborne campaign took place in spring 2022. Among other aircraft, it involved the Polar 6 research aircraft stationed in Longyearbyen on Svalbard. Polar 6 was equipped with a wide range of in-situ instruments to measure meteorological and aerosol properties in the Arctic atmosphere around Svalbard and the Fram Strait. In order to understand the origin of air masses sampled by Polar 6, this dataset here was created as follows. For all research flights, every one minute along the flight track and at the coordinates and pressure altitude of Polar 6, one air mass was initialized using the the trajectory calculation tool Lagranto in conjunction with wind fields from the ERA5 reanalysis. Latter has an output resolution of around 30 km and one hour. The hourly data was bi-linearly interpolated to one minute resolution. Trajectories were then calculated five days backwards in one minute steps. Several parameters were traced along the trajectories, based on ERA5 output: Surface pressure, geopotential altitude, atmospheric boundary-layer height, air temperature, specific humidity, sea-ice concentration, and cloud liquid/ice/rain/snow water contents. Thus, it is possible to investigate the origin of the sampled air masses, as well as to estimate the relevant air-mass transformations and cloud processes they underwent during transport towards Polar 6.