Results of supervised classification of six Landsat 8 images acquired on: 25 May, 3 June, 22 June, 15 July, 4 August and 20 August 2014, covering glaciers in Hornsund fiord. Method of classification: Maximum Likelihood. The results show variability of snow cover areas in melting period of 2014 for glaciers located in Hornsund fiord and larger than 9 km2 (Körberbreen, Samarinbreen, Chomjakovbreen, Mendelejevbreen, Svalisbreen, Hornbreen, Storbreen, Kvalfangarbreen, Mühlbacherbreen, Paierlbreen and Hansbreen). For more information, please check: https://doi.org/10.3390/w9100804 Overview: Results of Maximum Likelihood classification of Landsat 8 images for analysed glaciers. Red - snow cover, yellow - glacier ice, black - debirs, grey - cloud cover.

The monitoring of the mass balance of the Werenskioldbreen (Wedel Jarlsberg Land, Spitsbergen, Svalbard) in the years 1999-2002 and 2009-2018. It is calculated on the base of 4 to 9 ablation stakes (depend on year). The mass balance is determined by conducting field surveys on floating calendar dates (floating-date system). Data have also been submitted to the World Glacier Monitoring Sevice (WGMS, https://wgms.ch)

• Data set of daily suspended sediment transport from the Breelva (glacier river), which drains the Werenskioldbreen (Southwestern Spitsbergen), for the period 2007–2012 (Appendix I). • Period of sampling, range of the suspended sediment concentration (SSC), total suspended sediment load (SSL), and the rate of mechanical denudation and also total annual runoff (Qtotal) from Werenskioldbreen catchment for the studied seasons (1972, 1986 and 2007–2012) (Appendix II). Detailed information can be found in: Pulina, M. Preliminary studies on denudation in SW Spitsbergen. Bull. Acad. Pol. Sci. Terre 1974, 22, 83–99. Krawczyk, W., Opołka-Gądek, J. Suspended sediment concentration in the Werenskiold Glacier drainage basin in 1986. In XXI Polar Symposium; Zalewski, M.S., Ed.; Institute of Geophysics Polish Academy of Sciences: Warszawa, Poland, 1994; pp. 215–224, ISBN 8385173374. Łepkowska E., Stachnik Ł., 2018. Which drivers control the suspended sediment flux in a High Arctic glacierized basin (Werenskioldbreen, Spitsbergen)? Water, 10, 1408. doi: https://doi.org/10.3390/w10101408

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

1. Two high-quality UAV movies taken in Hornsund fiord on 15th Sep 2016 with Phantom 3 Advanced usage. The movies are focused on Horyzont II ship during unloading goods to the Polish Polar Station Hornsund. Format file: .MOV. 2. Dataset consist six UAV movies taken in neighborhood of stake no. 4 of Hansbreen, one taken in the vicinty of stake no. 6 of Hansbreen and two on Tuvbreen. The movies from stake no. 4 show the ablation zone, crevasses, glaciers in the area and a team of University of Silesia scientists during maintanance of automatic weather station (AWS). The movie from stake no. 6 presents the surface of Hansbreen towards accumulation zone. The movies from Tuvbreen show the area around, surface of the glacier and University of Silesia team. UAV: Phantom 3 Advanced. Format file: .MOV. 3. One high-quality UAV movie taken from West morain of Paierbreen 22nd Aug 2016 with Phantom 3 Advanced usage. The movie is focused on the front of Paierlbreen. Format file: .MOV. 4. Two high-quality UAV movies taken on Silesiabreen 23nd Aug 2016 with Phantom 3 Advanced usage. The movie is focused on the snowline of Silesiabreen, University of Silesia scietists while fieldwork and neighbourhood. 5. UAV movie of Storbreen upper ablation area in 21st Aug 2016. 6. Three high-quality UAV movies taken from vicinity of Treskelen in Hornsund on 12 Sep 2016 with Phantom 3 Advanced usage. The movies are focused on the University of Silesia team during automatic weather station maintanance, sailing boat operated by scientists and Hornsund fiord. 7. A high-quality UAV movie taken from vicinity of Brateggbreen on 5 Sep 2016 with Phantom 3 Advanced usage. The movie is focused on Brateggbreen front and its proglacial lake. Format file: .MOV. 8. UAV movies of Werenskoildbreen front and morain in summer 2016

Dataset contains surface elevation along spring GPR profiles performed on Hansbreen and Werenskioldbreen. Fieldwork has been done with dGPS device in kinematic mode at the end of ablation season in 2013 and 2015 to compare it with spring GPR survey and calculate surface ablation. 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)

1. Dataset of UAV vertical aerial photos of front and ice melange in the north part of Tunabreen, obtained in spring 2017. Area covered: ~1600x~800m. Used UAV: Phantom 3 Advanced, flight height: 100m. Data obtained during fieldwork supported by Svalbard Science Forum, Arctic Field Grant 2017 with cooperation with University of Maine (USA) and the University Centre in Svalbard (Norway).

Dataset contains results of GPR survey performed with 800 MHz antennas for snow depth calculation. Fieldwork has been done during peak of accumulation, along repeated profiles on several glaciers in the region of Hornsund, Svalbard: Amundsenisen (2013) Werenskioldbreen (2013, 2014, 2015) Nannbreen (2013) Ariebreen (2014) Flatbreen (2018) Storbreen (2018) 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.,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

Meteorological data from Aavatsmark Glacier (Aavatsmarkbreen)

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