A Parrot Sequoia+ multispectral camera on a Parrot Bluegrass drone registered in four spectral bands (green, red, red edge (RE), and near-infrared (NIR)) to identify glacial outflow zones and determined the meltwater turbidity values in waters in front of the following Antarctic glaciers: Ecology, Dera Icefall, Zalewski, and Krak on King George Island, Southern Shetlands was used. This process was supported by a Red-Green-Blue (RGB) colour model from a Zenmuse X5 camera on an Inspire 2 quadcopter drone. Additional surface water turbidity measurements were carried out using a Yellow Springs Instruments (YSI) sonde EXO2. From this research, it was apparent that for mapping low-turbidity and medium-turbidity waters (<70 formazinenephelometricunits (FNU)), a red spectral band should be used, since it is insensitive to possible surface ice phenomena and registers the presence of both red and white sediments. High-turbidity plumes with elevated FNU values should be identified through the NIR band. Strong correlation coefficients between the reflectance at particular bands and FNU readings (RGreen = 0.85, RRed = 0.85, REdge = 0.84, and RNIR = 0.83) are shown that multispectral mapping using Unmanned Aerial Vehicles (UAVs) can be successfully usedeven in the unfavourable weather conditions and harsh climate of Antarctica. Lastly, the movement of water masses in Admiralty Bay is briefly discussed and supported by the results from EXO2 measurements.

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Abstract. During the 38 months between December 2018 and January 2022, multiparameter hydrographic measurements were taken at 31 sites within Admiralty Bay, King George Island, Antarctica. These records consisted of water column measurements (down to 100 m) of temperature, conductivity, turbidity, and pH as well as the dissolved oxygen, dissolved organic matter, chlorophyll-a and phycoerythrin contents. The sites were chosen due to their variable distances from glacial fronts and open ocean waters. Fifteen sites were localized within smaller glacial coves, with waters highly impacted by glacial infusions; seven sites were located in the open waters of the main body of Admiralty Bay; and nine sites were located in the intermediate conditions of the Ezcurra Inlet. The final dataset consists of measurements carried out over 142 separate days, with an average of 3.74 measurements per month. However, data were not collected regularly throughout the year and were collected less frequently during winter, although data were gathered for all but 2 winter months. On average, each site was investigated 98.2 times. Due to calibration issues, absolute values of optically measured properties occasionally show unrealistic negative values, but the relative distributions of these values remain valid. Variabilities in the measured properties each season and throughout the whole duration of the project reveal regular oscillations as well as possible long-term trends. The described dataset is freely available at PANGAEA: https://doi.org/10.1594/PANGAEA.947909 (Osińska et al., 2022).

This study enabled us to determine the sources of sediment for glacial catchments and investigate the differences in properties, i.e., suspended sediment concentration (SSC), turbidity measured in the laboratory (TLAB) and in the field (TF), mean particle diameter (MPD) and chemical composition, between two different-colored sediments that flowed from the glacier terminus. Additionally, the relationship between these properties for two types of suspensions and remote sensing reflectance (RRS) was tested, and the factor with the greatest impact on the value of RRS was determined. The results showed that within one catchment area, there were 4 sediment sources that provide white (S.1) and red (S.2) sediment. Chemical analysis showed that the differences in sediment color may be influenced by the increased content of carbonates in the white sediment (S.1). The S.2 sediment is characterized by mean TLAB, TF, and SSC values higher than 26.6 formazine nephelometric units (FNU), 13.5 FNU, and 50 mg/L, respectively, and the mean MPD was 4.25 lower than that of the S.1 sediment. However, the red sediment had on average 0.1 lower RRS than the white sediment. In addition, the properties of S.1 correlated better with reflectance, reaching a maximum correlation of 0.69 (SSC/RRS 770-810 nm), while S.2 exhibited a negative correlation in 7 out of 12 cases, reaching a maximum correlation of 0.16 (TLAB/SSC/RRS 730-740 nm) and a negative correlation of -0.37 (SSC/RRS 530-570 nm). This result indicated that sediment color may be a key factor in the dependence of glacial suspension properties and spectral reflectance.