High-resolution orthomosaic derived from aerial images captured in 2020 over Hornsund, Svalbard by Dornier aircraft. The spatial resolution of the orthomosaic is 0.087 m. Aerial images for the area were provided by the SIOS through a dedicated call of proposals (https://sios-svalbard.org/AirborneRS). The dataset is the supplement to the paper: Błaszczyk, M.; Laska, M.; Sivertsen, A.; Jawak, S.D. Combined Use of Aerial Photogrammetry and Terrestrial Laser Scanning for Detecting Geomorphological Changes in Hornsund, Svalbard. Remote Sens. 2022, 14, 601. https://doi.org/10.3390/rs14030601

Downwelling longwave flux in air measurements from AWS located on the Werenskioldbreen. The sensors are installed on a mast that is mounted in the glacier ice. During the season, the distance between the glacier's surface and the sensors increases. The station is serviced at least once a year between March and April.

Permafrost monitoring System of thermistors (temperature strings with loggers) to monitor the ground thermal state Precise data on the thermal state of the frozen ground is one of the key missing components of the environmental monitoring at the research stations spread across Spitsbergen. The CRIOS project will allow us to equip the newly established borehole with precise temperature strings that will record ground thermal changes over the next couple of years. A system of temperature strings will be used in the monitoring of the thermal state of permafrost in drilled boreholes. Devices were tested in severe weather and are commonly used for permafrost monitoring by other research groups working in polar regions. Site Information The borehole near the UMK station in Kaffioyra was located at the existing meteorological garden, about 100 m from the shoreline. The drilling was carried out on 20-21.07.2023. The substrate is dominated by loose sandy-gravel beach sediments. A large amount of fine material and the formation of a core in a small part of the hole made it possible to reach a depth of 10.0 m below sea level. CRIOS – Cryosphere Integrated Observation Network on Svalbard Project financed from the EEA Financial Mechanism 2014-2021 operated by the National Science Centre in Poland Agreement no. UMO-2022/43/7/ST10/00001 to a predefined project no. 2022/43/7/ST10/00001 Project period: 08.09.2022 - 30.04.2024 (2029)

• Discharge measurements were conducted from May/June/July to September/October in the years 2007–2012. Direct observation periods were 62, 51, 61, 40, 121, and 35 days in the consecutive years. The data set was obtained from CTD-DIVER DI 261 or Mini-Diver (Van Essen Instruments, Delft, The Netherlands) logger with barometric compensation by BaroDiver (Schlumberger, Houston, TX, USA) with 10-min intervals and flow velocities were measured with a SEBA F1 current meter (SEBA Hydrometrie GmbH, Kaufbeuren, Germany). Mean daily discharge and total runoff in the hydrologically active season was calculated on the basis of the 24h running average of the water level and a rating curve (Appendix 1). More details have been reported by Majchrowska E., Ignatiuk D., Jania J., Marszałek H., Wąsik M., 2015: Seasonal and interannual variability in runoff from the Werenskioldbreen catchment, Spitsbergen. Polish Polar Research vol. 36, no. 3, pp. 197–224. doi: 10.1515/popore−2015−0014 • Hydrological data for Werenskioldbreen - archive of the University of Silesia. The base contain mean daily discharge in the years: 1972, 1973, 1974, 1979, 1980, 1983, 1985, 1986, 1988, 1998, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2017 (18 hydrologically active seasons) – Appendix 2

Time-lapse cameras In order to determine the state of coverage of the area, e.g. period of snow cover on a tundra, the extent of the glacier front, etc., it is necessary to perform photographic imaging at a specific time interval. This will allow for precise diagnosis of snow conditions. The camera is installed in the glacier catchment area at the hydrological station. CRIOS – Cryosphere Integrated Observation Network on Svalbard Project financed from the EEA Financial Mechanism 2014-2021 operated by the National Science Centre in Poland Agreement no. UMO-2022/43/7/ST10/00001 to a predefined project no. 2022/43/7/ST10/00001 Project period: 08.09.2022 - 30.04.2024 (2029)

Digital elevation model (DEM) with high spatial resolution derived from aerial images captured in 2020 over Hornsund, Svalbard by Dornier aircraft. The spatial resolution of the orthomosaic is 0.169 m. Aerial images for the area were provided by the SIOS through a dedicated call of proposals (https://sios-svalbard.org/AirborneRS). The dataset is the supplement to the paper: Błaszczyk, M.; Laska, M.; Sivertsen, A.; Jawak, S.D. Combined Use of Aerial Photogrammetry and Terrestrial Laser Scanning for Detecting Geomorphological Changes in Hornsund, Svalbard. Remote Sens. 2022, 14, 601. https://doi.org/10.3390/rs14030601

Englacial water pressure was recorded by placing HOBO 250-Foot Depth Water Level Data Loggers in the center of Crystal Cave (N77°02' E15°34', 174 m) channel system (Hansbreen glacier). Data loggers were set to record values every 30 minutes, resampled to daily in post-processing, and have a resolution of 2.55 kPa for a typical error of 3.8 cm water level. Water pressure was converted in water level. Sensor was placed in the cave by drilling anchor points into the ice above a vertical shaft, then hanging cables down in the center of conduit. Stabilization cables were used to keep sensors from attaching to and freezing into ice walls by manually rappelling down to the sensor and attaching it to three horizontal cables, anchored into the ice walls at about 120 degrees apart. Senor was installed in Crystal Cave at about 100 m total distance from the cave entrance, in ice about 74 m thick. The sensor was installed 28 m above the glacier bed and 46 m below the ice surface.

Relative humidity measurements from AWS located on the Werenskioldbreen. The sensors are installed on a mast that is mounted in the glacier ice. During the season, the distance between the glacier's surface and the sensors increases. The station is serviced at least once a year between March and April.

Inventory of tidewater and landbased glaciers delineated from archival satellite images (ASTER, Landsat) for Southern Spitsbergen. Tidewater glaciers are delineated based on satellite data from 2010. Landbased glacier are extracted from different satellite data (2005-2010). Shapefiles have basic information in the attribute table (name, ID, area, type of glaciers). Detailed description of the source data and accuracy data for glaciers from hydrological basin of Hornsund can be found in: Błaszczyk M., Jania J.A., Kolondra L., 2013: Fluctuations of tidewater glaciers in Hornsund Fiord (Southern Svalbard) since the beginning of the 20th century. Polish Polar Research, 34( 4): 327-352.http://journals.pan.pl/dlibra/publication/114504/edition/99557/content

The dataset includes point winter and summer mass balance measurements on ablation stakes in 2009-2020 and the calculated point annual mass balance. The dataset includes part of the results from the project “Hindcasting and projections of hydro-climatic conditions of Southern 350 Spitsbergen” (grant no. 2017/27/B/ST10/01269) financed by the Polish National Science Centre, “Arctic climate system study of ocean, sea ice, and glaciers interactions in Svalbard area”—AWAKE2 (Pol-Nor/198675/ 17/2013), supported by the National Centre for Research and Development within the Polish–Norwegian Research Cooperation Programme and the SvalGlac—Sensitivity of Svalbard glaciers to climate change, the ESF Project, the project Integrated Arctic 355 Observing System (INTAROS)- Horizon 2020, the ice2sea 7th FP projects. The studies were carried out as part of the scientific activity of the Centre for Polar Studies (University of Silesia in Katowice) with the use of research and logistic equipment of the Polar Laboratory of the University of Silesia in Katowice.