Melting Characteristics of Snow Cover on Tidewater Glaciers in Hornsund Fjord, Svalbard

In recent years, the Svalbard area, especially its southern section, has been characterised by an exceptionally thin snow cover, which has a significant impact of the annual mass balance of glaciers. The objective of this study was to determine melting processes of the snow cover deposited on 11 glaciers that terminate into Hornsund Fjord during the melting period of 2014. The study included analyses of snow pits and snow cores, meteorological data collected from automatic weather stations and Polish Polar Station Hornsund, and supervised classification of six Landsat 8 images for assessing the progress of snow cover melting. The calculated Snow-Covered Area (SCA) varied from 98% at the beginning of the melting season to 43% at the end of August. The melting vertical gradient on Hansbreen was -0.34 m 100 m-1, leading to surface melting of -1.4 cm water equivalent (w.e.) day-1 in the ablation zone (c. 200 m a.s.l. (above sea level)) and -0.7 cm w.e. day-1 in the accumulation zone (c. 400 m a.s.l.). Furthermore, the study identified several observed features such as low snow depth in the accumulation zone of the Hornsund glaciers, a large proportion of the snow layers (12-27%) produced by rain-on-snow events, and a frequent occurrence of summer thermal inversions (80% annually), indicating that the area is experiencing intensive climate changes

Influence of snowpack internal structure on snow metamorphism and melting intensity on Hansbreen, Svalbard

This paper presents a detailed study of melting processes conducted on Hansbreen - a tidewater glacier terminating in the Hornsund fjord, Spitsbergen. The fieldwork was carried out from April to July 2010. The study included observations of meltwater distribution within snow profiles in different locations and determination of its penetration time to the glacier ice surface. In addition, the variability of the snow temperature and heat transfer within the snow cover were measured. The main objective concerns the impact of meltwater on the diversity of physical characteristics of the snow cover and its melting dynamics. The obtained results indicate a time delay between the beginning of the melting processes and meltwater reaching the ice surface. The time necessary for meltwater to percolate through the entire snowpack in both, the ablation zone and the equilibrium line zone amounted to c. 12 days, despite a much greater snow depth at the upper site. An elongated retention of meltwater in the lower part of the glacier was caused by a higher amount of icy layers (ice formations and melt-freeze crusts), resulting from winter thaws, which delayed water penetration. For this reason, a reconstruction of rain-on-snow events was carried out. Such results give new insight into the processes of the reactivation of the glacier drainage system and the release of freshwater into the sea after the winter period

Importance of snow as component of surface mass balance of Arctic glacier (Hansbreen, southern Spitsbergen)

Snowmelt is a very important component of freshwater resources in the polar environment. Seasonal fluctuations in the water supply to glacial drainage systems influence glacier dynamics and indirectly affect water circulation and stratification in fjords. Here, we present spatial distribution of the meltwater production from the snow cover on Hansbreen in southern Spitsbergen. We estimated the volume of freshwater coming from snow deposited over this glacier. As a case study, we used 2014 being one of the warmest season in the 21st century. The depth of snow cover was measured using a high frequency Ground Penetrating Radar close to the maximum stage of accumulation. Simultaneously, a series of studies were conducted to analyse the structure of the snowpack and its physical properties in three snow pits in different glacier elevation zones. These data were combined to construct a snow density model for the entire glacier, which together with snow depth distribution represents essential parameters to estimate glacier winter mass balance. A temperature index model was used to calculate snow ablation, applying an average temperature lapse rate and surface elevation changes. Applying variable with altitude degree day factor, we estimated an average daily rate of ablation between 0.023 m d-1 °C-1 (for the ablation zone) and 0.027 m d-1 °C-1 (in accumulation zone). This melting rate was further validated by direct ablation data at reference sites on the glacier. An average daily water production by snowmelt in 2014 ablation season was 0.0065 m w.e. (water equivalent) and 41.52·106 m3 of freshwater in total. This ablation concerned 85.5% of the total water accumulated during winter in snow cover. Extreme daily melting exceeded 0.020 m w.e. in June and September 2014 with a maximum on 6th July 2014 (0.027 m w.e.). The snow cover has completely disappeared at the end of ablation season on 75.8% of the surface of Hansbreen

The Role of Winter Rain in the Glacial System on Svalbard

Rapid Arctic warming results in increased winter rain frequencies, which may impact glacial systems. In this paper, we discuss climatology and precipitation form trends, followed by examining the influence of winter rainfall (Oct–May) on both the mass balance and dynamics of Hansbreen (Svalbard). We used data from the Hornsund meteorological station (01003 WMO), in addition to the original meteorological and glaciological data from three measurement points on Hansbreen. Precipitation phases were identified based on records of weather phenomena and used—along with information on lapse rate—to estimate the occurrence and altitudinal extent of winter rainfall over the glacier. We found an increase in the frequency of winter rain in Hornsund, and that these events impact both glacier mass balance and glacier dynamics. However, the latter varied depending on the degree of snow cover and drainage systems development. In early winter, given the initial, thin snow cover and an inefficient drainage system, rainfall increased glacier velocity. Full-season winter rainfall on well-developed snow was effectively stored in the glacier, contributing on average to 9% of the winter accumulation

The Second Cross-Lingual Challenge on Recognition, Normalization, Classification, and Linking of Named Entities across Slavic Languages

We describe the Second Multilingual Named Entity Challenge in Slavic languages. The task is recognizing mentions of named entities in Web documents, their normalization, and cross-lingual linking The Challenge was organized as part of the 7th Balto-Slavic Natural Language Processing Workshop, co-located with the ACL-2019 conference. Eight teams participated in the competition, which covered four languages and five entity types. Performance for the named entity recognition task reached 90% F-measure, much higher than reported in the first edition of the Challenge. Seven teams covered all four languages, and five teams participated in the cross-lingual entity linking task. Detailed evaluation information is available on the shared task web page.Non peer reviewe

The Second Cross-Lingual Challenge on Recognition, Normalization, Classification, and Linking of Named Entities across Slavic Languages

We describe the Second Multilingual Named Entity Challenge in Slavic languages. The task is recognizing mentions of named entities in Web documents, their normalization, and cross-lingual linking The Challenge was organized as part of the 7th Balto-Slavic Natural Language Processing Workshop, co-located with the ACL-2019 conference. Eight teams participated in the competition, which covered four languages and five entity types. Performance for the named entity recognition task reached 90% F-measure, much higher than reported in the first edition of the Challenge. Seven teams covered all four languages, and five teams participated in the cross-lingual entity linking task. Detailed evaluation information is available on the shared task web page.Non peer reviewe

Newly identified climatically and environmentally significant high-latitude dust sources

Dust particles from high latitudes have a potentially large local, regional, and global significance to climate and the environment as short-lived climate forcers, air pollutants, and nutrient sources. Identifying the locations of local dust sources and their emission, transport, and deposition processes is important for understanding the multiple impacts of high-latitude dust (HLD) on the Earth\u27s systems. Here, we identify, describe, and quantify the source intensity (SI) values, which show the potential of soil surfaces for dust emission scaled to values 0 to 1 concerning globally best productive sources, using the Global Sand and Dust Storms Source Base Map (G-SDS-SBM). This includes 64 HLD sources in our collection for the northern (Alaska, Canada, Denmark, Greenland, Iceland, Svalbard, Sweden, and Russia) and southern (Antarctica and Patagonia) high latitudes. Activity from most of these HLD sources shows seasonal character. It is estimated that high-latitude land areas with higher (SI ≥0.5), very high (SI ≥0.7), and the highest potential (SI ≥0.9) for dust emission cover >1 670 000 km$^{2}$, >560 000 km$^{2}$, and >240 000 km$^{2}$, respectively. In the Arctic HLD region (≥60$^{∘}$ N), land area with SI ≥0.5 is 5.5 % (1 035 059 km$^{2}$), area with SI ≥0.7 is 2.3 % (440 804 km$^{2}$), and area with SI ≥0.9 is 1.1 % (208 701 km$^{2}$). Minimum SI values in the northern HLD region are about 3 orders of magnitude smaller, indicating that the dust sources of this region greatly depend on weather conditions. Our spatial dust source distribution analysis modeling results showed evidence supporting a northern HLD belt, defined as the area north of 50$^{∘}$ N, with a “transitional HLD-source area” extending at latitudes 50–58∘ N in Eurasia and 50–55$^{∘}$ N in Canada and a “cold HLD-source area” including areas north of 60$^{∘}$ N in Eurasia and north of 58$^{∘}$ N in Canada, with currently “no dust source” area between the HLD and low-latitude dust (LLD) dust belt, except for British Columbia. Using the global atmospheric transport model SILAM, we estimated that 1.0 % of the global dust emission originated from the high-latitude regions. About 57 % of the dust deposition in snow- and ice-covered Arctic regions was from HLD sources. In the southern HLD region, soil surface conditions are favorable for dust emission during the whole year. Climate change can cause a decrease in the duration of snow cover, retreat of glaciers, and an increase in drought, heatwave intensity, and frequency, leading to the increasing frequency of topsoil conditions favorable for dust emission, which increases the probability of dust storms. Our study provides a step forward to improve the representation of HLD in models and to monitor, quantify, and assess the environmental and climate significance of HLD

Thermal Sensitivity of High Mountain Lakes: The Role of Morphometry and Topography (The Tatra Mts., Poland)

This study presents the results of a 5-year monitoring program of ice cover, water temperature, and local meteorological conditions carried out in three reference lakes in the periglacial zone of the Polish Tatra Mountains. On the basis of this information, the relationships between the weighted mean water temperature of each of these lakes and the air temperature, wind speed, precipitation, and ice–snow cover in the summer, spring, and autumn seasons, as well as year-round, were described, and the roles of the morphometry of lakes and the topography of their catchments were determined. It was found that the sensitivity of the lakes to climate warming increased with a decrease in their area/depth and shade, and with an increase in altitude and the share of wind-blown snow in the formation of the ice–snow cover. An increase in the mean annual air temperature does not necessarily translate into the warming of lakes, but, paradoxically, may result in their cooling. The current climate may not be best reflected by the most sensitive lakes, but rather by the largest ones located in the subalpine zone

Combined Use of Aerial Photogrammetry and Terrestrial Laser Scanning for Detecting Geomorphological Changes in Hornsund, Svalbard

The Arctic is a region undergoing continuous and significant changes in land relief due to different glaciological, geomorphological and hydrogeological processes. To study those phenomena, digital elevation models (DEMs) and highly accurate maps with high spatial resolution are of prime importance. In this work, we assess the accuracy of high-resolution photogrammetric DEMs and orthomosaics derived from aerial images captured in 2020 over Hornsund, Svalbard. Further, we demonstrate the accuracy of DEMs generated using point clouds acquired in 2021 with a Riegl VZ®-6000 terrestrial laser scanner (TLS). Aerial and terrestrial data were georeferenced and registered based on very reliable ground control points measured in the field. Both DEMs, however, had some data gaps due to insufficient overlaps in aerial images and limited sensing range of the TLS. Therefore, we compared and integrated the two techniques to create a continuous and gapless DEM for the scientific community in Svalbard. This approach also made it possible to identify geomorphological activity over a one-year period, such as the melting of ice cores at the periglacial zone, changes along the shoreline or snow thickness in gullies. The study highlights the potential for combining other techniques to represent the active processes in this region

Changes in the Structure of the Snow Cover of Hansbreen (S Spitsbergen) Derived from Repeated High-Frequency Radio-Echo Sounding

This paper explores the potential of ground-penetrating radar (GPR) monitoring for an advanced understanding of snow cover processes and structure. For this purpose, the study uses the Hansbreen (SW Spitsbergen) records that are among the longest and the most comprehensive snow-cover GPR monitoring records available on Svalbard. While snow depth (HS) is frequently the only feature derived from high-frequency radio-echo sounding (RES), this study also offers an analysis of the physical characteristics (grain shape, size, hardness, and density) of the snow cover structure. We demonstrate that, based on GPR data (800 MHz) and a single snow pit, it is possible to extrapolate the detailed features of snow cover to the accumulation area. Field studies (snow pits and RES) were conducted at the end of selected accumulation seasons in the period 2008–2019, under dry snow conditions and HS close to the maximum. The paper shows that although the snow cover structure varies in space and from season to season, a single snow pit site can represent the entire center line of the accumulation zone. Numerous hard layers (HLs) (up to 30% of the snow column) were observed that reflect progressive climate change, but there is no trend in quantity, thickness, or percentage contribution in total snow depth in the study period. HLs with strong crystal bonds create a “framework” in the snowpack, which reduces compaction and, consequently, the ice formation layers slow down the rate of snowpack metamorphosis. The extrapolation of snow pit data through radar profiling is a novel solution that can improve spatial recognition of snow cover characteristics and the accuracy of calculation of snow water equivalent (SWE)