Snow depth data series contain records obtained by high frequency GPR on selected glaciers of Hornsund area (S Svalbard) since 2008. Currently the largest collection regards Hansbreen. Data for other glaciers are successively appended. The GPR survey on Hansbreen is regularly carried out approximately along the same tracks. Due to dynamically changing glacier surface topography influencing different survey abilities the some parts of profiles are modified in consecutive seasons. The total distance of Hansbreen profiles are as follows (Fig.1): 63.9 km (2008), 117,5 km (2011), 105,1 km (2013), 103,9 km (2014), 98,5 km (2015), 91,1 km (2016), 101,0 km (2017) and 108,4 km (2018).

Dataset contains detailed measurements of physical features of seasonal snow cover, according to International Classification of Seasonal Snow on the Ground (Fierz et al. 2009). Fieldwork has been done during peak of accumulation on several glaciers in the region of Hornsund, Svalbard: Amundsenisen (2013) Hansbreen (three sites; 2010, 2012, 2013, 2014, 2015, 2017, 2018) Werenskioldbreen (two sites; 2013, 2015) Nannbreen (2013) Ariebreen (2014) Acknowledgements: Research Council of Norway, Arctic Field Grant 2013: Spatial distribution of snow cover and drainage systems on the glaciers on Wedel Jarlsberg Land (RiS ID: 6158); the National Science Centre PRELUDIUM 4: Role of meltwater from snow cover for supplying drainage systems of the Spitsbergen glaciers (2012/07/N/ST10/03784) References: Laska M., Luks B., Budzik T., 2016. Influence of snowpack internal structure on snow metamorphism and melting intensity on Hansbreen, Svalbard. Polish Polar Research, 37(2): 193–218. doi:10.1515/popore-2016-0012 Laska M., Grabiec M., Ignatiuk D., Budzik T., 2017. Snow deposition patterns on southern Spitsbergen glaciers, Svalbard, in relation to recent meteorological conditions and local topography. Geografiska Annaler, Series A: Physical Geography, 99(3): 262–287 doi:10.1080/04353676.2017.1327321 Laska M., Barzycka B., Luks B., 2017. Melting Characteristics of Snow Cover on Tidewater Glaciers in Hornsund Fjord, Svalbard. Water, 9(10), 804. doi:10.3390/w9100804

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. On the coastal section selected for drilling at Calypsobyen, the bedrock contains siltstone and sandstone forming relict abrasion platforms, which are currently covered by loose sand and gravel beach sediments. The borehole was located near the mouth of the Scott River (right bank), at a distance of about 75 m from the shoreline and 900 m from the station. After stopping the drilling progress again at 5 m below sea level, a decision was made to install a string in the third hole. 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)

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.

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)

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)

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. 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)

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. The hole in the vicinity of the UAM station in Petuniabukta was delineated at a distance of about 50 m from the shoreline, in the zone between the Polish and Czech stations. The drilling was carried out on 22-23.07.2023. The bedrock is built up by siltstone and sandstone. At the drilling site, they are covered by thick-bedded beach sediments. During the drilling, a depth of 7 meters below sea level was reached, and with no further drilling progress, a decision was made to install a string to the depth obtained. 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)

Dataset contains evolution of the snow temperature within seasonal snowpack on Hansbreen. Fieldwork has been performed with several thermistors located at different levels (from snow surface to the bottom, on glacier ice) from April to July 2010 (during period of early and intensive surface melting). Study has been repeated in 2015, at the same location. Acknowledgements: Research Council of Norway, Arctic Field Grant 2013: Spatial distribution of snow cover and drainage systems on the glaciers on Wedel Jarlsberg Land (RiS ID: 6158); the National Science Centre PRELUDIUM 4: Role of meltwater from snow cover for supplying drainage systems of the Spitsbergen glaciers (2012/07/N/ST10/03784) References: Laska M., Luks B., Budzik T., 2016. Influence of snowpack internal structure on snow metamorphism and melting intensity on Hansbreen, Svalbard. Polish Polar Research, 37(2): 193–218. doi:10.1515/popore-2016-0012

In the years 2009-2019, 49 samplings (shallow drilling or snowpits) were made on the glacier during the spring measurement campaigns in order to determine the bulk snow density and SWE. The average density of snow cover ranges from 386 to 447 kg/m3. 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.