Quasi-Lagrangian air mass matches during HALO-(AC)3: Matches occuring on the same day

• Main Authors: Kirbus, Benjamin, Ehrlich, André, Schäfer, Michael, Wendisch, Manfred
• Format: Dataset
• Language: English
• Published: PANGAEA 2024
• Subjects: AC; AC3; Aircraft; Arctic; Arctic Amplification; Date/Time of event; Event label; HALO; HALO_220312a; HALO_220313a; HALO_220314a; HALO_220315a; HALO_220316a; HALO_220320a; HALO_220321a; HALO_220328a; HALO_220329a; HALO_220330a; HALO_220401a; HALO_220404a; HALO_220407a; HALO_220408a; HALO_220410a; HALO_220411a; HALO_220412a; HALO_AC3; HALO-(AC)³; Image; Lagrangian data; Optional event label; RF02; RF03; RF04; RF05; RF06; RF07; RF08; RF09; RF10; RF11; RF12; RF13; RF14; RF15; RF16; RF17; RF18; Text file; trajectories
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.967143; https://doi.org/10.1594/PANGAEA.967143

One of the main goals of the HALO-(AC)3 Arctic airborne campaign conducted in spring 2022 was a quasi-Lagrangian sampling of air masses. This means that the same air masses were to be sampled twice. Such a measurement strategy allows for concrete observations of air mass transformations, which can for example be used to benchmark weather models. After finishing the campaign, trajectory calculations were conducted for all flights of the HALO aircraft to check whether the flight strategy was a success. For this, the trajectory calculation tool Lagranto was used 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. Air masses were initialized temporally every one minute along the flight track of HALO, and vertically every 5 hPa between 250 hPa and 10 hPa above the ground level. Horizontally, air masses were started within a 30 km radius circle centered around the location of HALO. In each circle, 30 air masses were initialized evenly spaced approximately every 10 km, allowing for a better statistical analysis. Trajectories were then calculated in one-minute steps up to 10 hours forward in time. At typical HALO flight times of up to 10 hours, around 2.7 million trajectories were calculated per research flight. A quasi-Lagrangian match is registered if the same air mass is seen again below HALO at a later time of the same day and within the same 30 km radius. In order to allow air masses to evolve, a minimum temporal threshold of one hour was applied between matches.