Vock, Clarissa; Spyrakos, Evangelos; Jerosch, Kerstin: Georeferenced multispectral Unmanned Aerial Vehicle reflectance data of meltwater plumes at King George Island, Antarctica (ANT-Land-SIGMA-I, Jan - Mar 2023 and ANT-Land-SIGMA-II, Dec 2024 - Feb 2025) [dataset bundled publication]. PANGAEA, https://doi.pangaea.de/10.1594/PANGAEA.998036 (dataset in review)

This dataset contains georeferenced, aligned, distortion- and vignetting-corrected, and radiometrically adjusted multispectral Unmanned Aerial Vehicle (UAV)-based reflectance imagery from a DJI Phantom 4 Multispectral quadcopter UAV, coupled to a GNSS reference mobile station DJI D-RTK 2. The dataset was collected from January until March 2023 in Maxwell Bay (Potter Cove and Marian Cove), and Admiralty Bay (Ezcurra Inlet and Lussich Cove) in the ANT-Land-SIGMA-I campaign, and during the austral summer of 2024/25 in Admiralty Bay (Mackellar Inlet and Lussich Cove, December 2024), and Maxwell Bay, including Potter Cove (January, February 2025), Marian Cove (January 2025), and Collins Harbour (February 2025), as well as Stranger Point (February 2025) within the ANT-Land-SIGMA-II campaign. Flight planning and mission control were conducted using the DJI GS Pro App (V. 2.0.17), which automatically adjusts the flight path to minimize battery consumption and achieve the desired capture overlap of 30% or a front overlap of 90% and a side overlap of 60%. The captures were taken at an altitude of 100m when possible, but the altitude was chosen lower during unfavourable weather conditions. UAV flights were conducted regardless of cloud cover, which was accounted for by the incident light sensor at the top of the UAV, solar angle, and the tidal state, but only at wind speeds below 10 m/s. Image post-processing, i.e., band alignment, vignetting, distortion correction, radiometric adjustment, and direct georeferencing, was performed using the DroneWQ library (https://github.com/aewindle110/DroneWQ), which was specifically designed for multispectral mapping of aquatic surfaces. This was adapted to be compatible with DJI P4M metadata and to follow the DJI processing guide (DJI 2020). Ground calibration panels were unavailable during fieldwork. For practicality, the conversion factor ρ_NIR between the camera and the sunlight sensor signal values was assumed to be 1. The obtained reflectance is therefore only proportional to a physically meaningful reflectance. Data collected during the second campaign contained strong sensor noise. To mitigate salt noise, affected images were filtered using a localised median filter (11x11 kernel).