Fast Ice Formation Research Articles

The impact of snow on fast ice formation in the area of the Bolshevik Island (Severnaya Zemlya Archipelago)

The impact of snow on fast ice formation in the area of the Bolshevik Island (Severnaya Zemlya Archipelago)

A study of sea ice regime in the Obskaya guba Bay using modern satellite data in 2007–2017

The Obskay guba Bay is a region of rapidly developing oil and gas exploration. Knowing the current sea ice conditions including dangerous phenomena e. g. ridges and stamukhas is important for the safety of coastal and underwater construction as well as for ecological risk assessment. With this study, we aim to obtain new data on sea ice seasonal cycle in the southern and central part of the Obskay guba Bay for 10 years (from 2007 to 2017) and to demonstrate the capacity of satellite data in obtaining varying sea ice characteristics in the region. Analyzing daily visual MODIS and available Sentinel-1 SAR imagery, we derived dates of sea ice and fast ice formation, fast ice breakup and melt onset and the onset of ice-free period. For this purpose the satellite data were analyzed manually by sea ice expert. In addition, of sea ice ridges were derived and the sea ice drift data wea automatically processed in order to locate motionless sea ice features — stamukhas. The distribution of sea ice floes and field size in the region was derived from MODIS data. The analysis showed that there is a tendency towards a shorter ice covered period based on the data from 2007 to 2017. Overall, the formation of sea ice starts 9 days later and fast ice breakup occurs 16 days earlier compared to the long-term mean (1947–2010). The majority of ridges were located in the central part of the region and directed along the coast. The analysis confirmed absence of large stamuhas visible to be applied method (with a horizontal size of 100 m). The predominant sea ice field size range lies 500–1500 m. The study shows that a combination of images obtained in the optical range of the survey with radar data makes it possible to supplement the classical visual assessments with the results of automatic methods for detecting fast ice, detecting stamukha, as well as ice drift and deformation.

Динамика припая Азовского моря в XXI веке

The article is dedicated to the investigation of the fast ice dynamics for the period 2000–2020 according to satellite data and field observations using GIS technologies. We used data from International Data Center – Sea Ice and coastal observation points to analyze long-term changes. Data processing and analysis was carried out using the ArcGIS 10.4 software package. As a result, data were obtained on the spatial and temporal variability of fast ice in the Sea of Azov for the 2000–2020. The area and width of fast ice, the periods of formation, destruction and duration were analyzed. The maps of the fast ice formation frequency were constructed for each month of the winter period: December–March. It is shown that the duration of fast ice on all coastal observation points decreased: for points on the northern coast Taganrog and Mariupol—by 3–5 days, for points on the southern coast of Taganrog Bay—Yeisk and Dolzhanskaya—by 10–12 days, for point Genichesk—7 days. Average long-term fast ice area for 2000–2020 is 1800 km2. But against the background of an increase in winter air temperatures, the fast ice area is decreasing, and in the last winter periods it is not observed. The width of the fast ice at the northern coast of the Sea of Azov and the Taganrog Bay is 5–10 km. In the western and southeastern parts of the sea (sections Temryuk, Arabatskaya and Obitochny), the fast ice width is 2–5 km on average over the winter and was observed in 25 % of cases.

Variability in the Distribution of Fast Ice and the Sub‐ice Platelet Layer Near McMurdo Ice Shelf

AbstractVariability in the volume of supercooled Ice Shelf Water outflow in McMurdo Sound is reflected in the thickness and distribution of fast ice and the sub‐ice platelet layer beneath. Ground‐based electromagnetic induction and drill hole surveys of the distribution and thickness of ice shelf‐influenced fast ice and the sub‐ice platelet layer in McMurdo Sound were carried out in late spring of 2011, 2013, 2016, and 2017. In 2011 and 2017, thicker sub‐ice platelet layers of up to 7.5 and 6 m were observed, respectively. Fast ice formation throughout the winters of 2011 and 2017 was influenced by a higher occurrence of strong southerly wind events and resultant activity of the Ross Sea Polynya. In contrast, lower wind conditions in 2016 led to largely undisturbed sea ice growth and anomalously extensive fast ice coverage. A thinner sub‐ice platelet layer of up to 4 m was observed in 2016. In 2011 and 2017, substantial and variable sub‐ice platelet layers were detected in a region of exchange of water masses between the Ross Sea and the McMurdo‐Ross ice shelf cavity, which were not observed in 2013 and 2016. We hypothesize that a higher frequency of strong southerly wind events, resultant polynya activity, and High Salinity Shelf Water production over winter accelerates circulation and increases melting in the proximal shallow McMurdo Ice Shelf and the deeper Ross Ice Shelf regions of the conjoined cavity. The outflow of supercooled Ice Shelf Water and sub‐ice platelet layer formation in McMurdo Sound are consequently promoted.

Evolving Instability of the Scar Inlet Ice Shelf based on Sequential Landsat Images Spanning 2005–2018

Following the large-scale disintegration of the Larsen B Ice Shelf (LBIS) in 2002, ice flow velocities for its remnants and tributary glaciers began to increase. In this study, we used sequential Landsat images spanning 2005–2018 to produce detailed maps of the ice flow velocities and surface features for the Scar Inlet Ice Shelf (SIIS). Our results indicate that the ice flow velocities for the SIIS and its tributary glaciers (Flask and Leppard Glaciers) have substantially increased since 2005. Surface features, such as rifts and crevasses, have also substantially increased in both scope and scale and are particularly evident in the region between the Leppard Glacier and the Jason Peninsula. Several indicators—including the acceleration of ice flows, the rapid growth of major surface rifts, the heavily enhanced surface crevasses, and the dynamic position of the ice front—point to the evolving instability of the SIIS. These same indicators describe the conditions for the LBIS leading up to its 2002 collapse. To date, however, the SIIS remains intact. The formation of fast ice supporting the ice shelf front, combined with moderate mean summer temperatures, may be preventing or delaying its collapse.

Change of structure and some physical properties of level fast ice during the spring and summer period of 2014 in the vicinity the research station “Ice base Cape Baranov”

The determination of the main physical properties of the fast ice around the research station “Ice base Cape of Baranov” was carried out from May 23 to August 7, 2014. At the beginning of the observations the ice was a system of three main layers reflecting the conditions of fast ice formation. The top 70 cm of the ice was formed under the conditions of dynamic variability. The ice formation to the level of 110 cm was more stable, and the lowerst layer below 110 cm grew without hummocking and thawing. In the second decade of June the ice accretion began on top due to recrystallization on snow and ice boundary. In the third decade of June the accretion process at the ice-snow interface was replaced by surface melting and destruction layer development. These changes are assumed to begin as maximum air temperatures keep above zero. By the second decade of July all the ice core had undergone serious internal changes. In the third decade of July the process of inter-crystalline-binding degradation affected the whole ice core.From the end of the third decade of June the formation of plate-like crystals was registered at the lower ice border, as well as the accretion of new ice in the form of layesr of various thickness and density. The process had reached the maximum by mid July when new ice up to 30 cm thick was formed. In the third decade of July this ice begun to melt. New ice accretion is primarily due to the presence of a layer of desalinated water under the ice.

Spatial heterogeneity in the structure of fast ice level in the area of the research station “Ice base Cape of Baranov”

Two ice coring transects in the Shokalsky Strait were made in order to analyze a spatialheterogeneity in the structure of fast ice in the area of the research station “Ice base Cape of Baranov”. The first transect was 16 km long made off the shore of Bolshevik Island in a western direction across the Shokalsky Strait. The second transect was made along the eastern shore of the Shokalsky Strait. Structural analysis of the recovered sea ice cores shows that fast ice in the Shokalsky Strait features a complicated multilayer structure formed of congelation ice, congelation-frazil ice, frazil slush, and infiltration formations. Various conditions of ice formation form the ices of various genetic types. In terms of ice thickness, a sequence of layer occurrence and type, all level fast ice of the Shokalsky Strait in the area of the station can be divided into three main groups. The group I, being the most common one, is the ice group formed directly in the strait, approximately outside the 100 m isobath. Its structure comprises three to four layers. The average ice thickness measured in the end of May was 132 cm. A distinctive feature of the ice belonging to (or associated with) this group is the presence of a distinct lamination in the texture pattern for almost all recovered ice cores. The ice of this group also has an increased salinity compared to the ice of other groups, especially in the upper layers.The ice of the group II prevails, mainly in closed bays or gulfs. This group ice forms in dynamically stable conditions. Formation of fast ice in these regions of the study area began some earlier than in other locations, and the thickness of this ice reached 160 cm or more.The ice of the group III is transitional from the group II to the group I. Its distinctive feature is the presence of a thick layer of rafting ice. The main place of its formation is the boundary of separation of fast ice with drifting ice or open water.In the Shokalsky Strait, in the bays and in the coastal regions, there was observed the spatial ordering of the columnar ice crystals. This feature was especially pronounced in level fast ice from the open part of the strait.

Seasonal and interannual variability of fast ice extent in the southeastern Laptev Sea between 1999 and 2013

AbstractAlong with changes in sea ice extent, thickness, and drift speed, Arctic sea ice regime is characterized by a decrease of fast ice season and reduction of fast ice extent. The most extensive fast ice cover in the Arctic develops in the southeastern Laptev Sea. Using weekly operational sea ice charts produced by Arctic and Antarctic Research Institute (AARI, Russia) from 1999 to 2013, we identified five main key events that characterize the annual evolution of fast ice in the southeastern Laptev Sea. Linking the occurrence of the key events with the atmospheric forcing, bathymetry, freezeup, and melt onset, we examined the processes driving annual fast ice cycle. The analysis revealed that fast ice in the region is sensitive to thermodynamic processes throughout a season, while the wind has a strong influence only on the first stages of fast ice development. The maximal fast ice extent is closely linked to the bathymetry and local topography and is primarily defined by the location of shoals, where fast ice is likely grounded. The annual fast ice cycle shows significant changes over the period of investigation, with tendencies toward later fast ice formation and earlier breakup. These tendencies result in an overall decrease of the fast ice season by 2.8 d/yr, which is significantly higher than previously reported trends.

Formation of the fast ice from the seasonal ice and its destruction

Considered is the theoretical mechanism of the formation of immovable ice cover along the coast (the fast ice) from the seasonal ice and the mechanism of its destruction. It is demonstrated that the process of formation and spread of the winter stable fast ice is determined by simultaneous impact of several factors: the morphometry of the coast and bottom, the width of the close ice, dynamic effects that shear stress forces of the flow and wind make on the ice, the duration of maintaining the condition of immobility and freezing (adhesion) of the ice, the thickness of adhered ice, and the intensity of thermal growth of ice from below. It is revealed that the permanent factor is the morphometry of coasts and the bottom while the other factors have temporal variability of various scales.

Some features of sea ice formation in Antarctic coastal waters

Considered are the peculiarities of fast ice formation in the Antarctic coastal waters. It is noted that the fine-crystalline ice with the chaotic orientation of crystals is mainly developed in the surface layers of the ice cover as well as the ice formed due to the infiltration of the sea water and its subsequent freezing in the lower layers of the snow cover. It is demonstrated that under the conditions of coastal Antarctic, the lamination of the structure during the period of ice cover formation and its subsequent development is the result of heavy precipitation in the form of snow and the formation of the large amount of snow sludge and crystals of intrawater ice (frazil ice) on the open water. The main distinctive feature of the Antarctic sea ice is its seasonal stratification with the formation of the surface layer of recrystallized ice and underlying destructive layers including the water interlayer in the ice column. The provision of the safety of overice movement of machinery requires the development of methods of continuous remote control of the snow-ice stratum of the fast ice.

An observational study of ice effects on Nelson River estuarine variability, Hudson Bay, Canada

Many estuaries in high latitude regions are subjected to seasonally ice-covered conditions. However, ice effects on estuarine variability have received limited scientific attention and remain poorly understood. In this paper, an 11-month mooring record is used to examine seasonal variation of estuarine hydrodynamics in the Nelson River estuary (NRE), Hudson Bay (HB), in northern Canada. We show that ice cover strongly affects tidal amplitudes, velocities and phases in the NRE. In the mid-winter, the M2 tidal amplitude and consequently the tidal range are significantly reduced due to under-ice friction in HB, while conversely the M2 tidal velocity is amplified due to reduction of cross-section of the channel by formation of fast ice. A stronger surface seaward residual flow observed in the winter indicates that the formation of fast ice could also enhance the residual circulation. Suspended sediment concentration in the river mouth is reduced, also possibly due to the formation of fast ice that protects shallow nearshore shoals from erosion. This study demonstrates the importance of ice effects on estuarine variability and the complexity of processes in a seasonally ice-covered estuary.

Evaluation of Arctic sea ice thickness simulated by Arctic Ocean Model Intercomparison Project models

Six Arctic Ocean Model Intercomparison Project model simulations are compared with estimates of sea ice thickness derived from pan‐Arctic satellite freeboard measurements (2004–2008); airborne electromagnetic measurements (2001–2009); ice draft data from moored instruments in Fram Strait, the Greenland Sea, and the Beaufort Sea (1992–2008) and from submarines (1975–2000); and drill hole data from the Arctic basin, Laptev, and East Siberian marginal seas (1982–1986) and coastal stations (1998–2009). Despite an assessment of six models that differ in numerical methods, resolution, domain, forcing, and boundary conditions, the models generally overestimate the thickness of measured ice thinner than ∼2 m and underestimate the thickness of ice measured thicker than about ∼2 m. In the regions of flat immobile landfast ice (shallow Siberian Seas with depths less than 25–30 m), the models generally overestimate both the total observed sea ice thickness and rates of September and October ice growth from observations by more than 4 times and more than one standard deviation, respectively. The models do not reproduce conditions of fast ice formation and growth. Instead, the modeled fast ice is replaced with pack ice which drifts, generating ridges of increasing ice thickness, in addition to thermodynamic ice growth. Considering all observational data sets, the better correlations and smaller differences from observations are from the Estimating the Circulation and Climate of the Ocean, Phase II and Pan‐Arctic Ice Ocean Modeling and Assimilation System models.

Unusual narwhal sea ice entrapments and delayed autumn freeze-up trends

Sea ice entrapments of narwhals (Monodon monoceros) occur when rapid changes in weather and wind conditions create a formation of fast ice in bays or passages used by whales. Between 2008 and 2010, four entrapments of narwhals were reported in Canada and Greenland. In each case, large groups (40–600 individuals) succumbed in the sea ice at three separate summering localities, two of these where entrapments had never before been reported. We examined long-term trends in autumn freeze-up timing (date when sea ice concentration rises above some threshold) on the 6 largest narwhal summering areas using sea ice concentration from satellite passive microwave data (1979–2009). We found strongly positive and significant trends (P < 0.001) in progressively later dates of autumn freeze-up in all summering areas. Autumn freeze-up occurs between 0.5 and 1 day later per year, or roughly 2–4 weeks later, over the 31-year time series. This indicates that sea ice conditions on narwhal summering areas are changing rapidly. The question remains whether entrapment events on summering areas are random or whether narwhals are adapting to changes in sea ice freeze-up by prolonging their summer residence time.

Formation of fast ice and its influence on the coastal zone of the Arctic seas

The formation of fast ice in the costal zone of freezing seas (immobile ice) is considered on the basis of a specially developed thermodynamic model that takes into account the energy exchange in the atmospheric boundary layer and the salinification of the water layer under the ice. The conditions at which the wind forced onshore motion of the ice under the influence of the wind stress at the ice’s surface is possible are studied using the example of the Baidaratskaya Guba in the Kara Sea.

Caspian Sea bottom scouring by hummocky ice floes

Forms of ice gouging were documented for the first time at 3 to 12 m depth in the North Caspian Sea. Gouges and systems of scouring gouges formed by drifting hummocky bodies frozen in ice floes have been discovered as a result of simultaneous hydroloca� tion survey and echosounding. The length of the larg� est and most welldefined gouges exceeds a few kilo� meters; the width of individual gouges is up to 5 m, and the width of gouge systems is up to 200 m. Apart from linear forms, local pits remaining from stamukhas sit� ting at the bottom have been discovered. Work on development of the existing hydrocarbon reserves in the North Caspian Sea has become active in the last 20 years; this work is supported by engineering and construction of stationary platforms, underwater pipelines, and other oil and gas infrastructure. For this reason estimation of the intensity of the ice impact that belongs to the category of hazardous natural pro� cesses is the key to geotechnical safety of the oil and gas infrastructure and environmental safety of the water areas. The Caspian Sea belongs to partially freezing seas. The ice conditions of the Caspian Sea are very com� plex and variable. Its northern part, which is shallow, freezes every year, in the central portion ice appears along the coast during severe winters only, while in the southern portion there is no ice at all (1). The ice sea� son in the North Caspian Sea lasts from November through March. Complete freezing and formation of fast ice usually take place north of the line from Chechen' Island to Kulaly Island (Fig. 1). During cold and extremely cold winters, fast ice can settle down to the 20 m isobath. Unlike the seas in the Arctic Region and the Far East, ice formation in the North Caspian Sea at a typ� ical water salinity of 2 to 11‰ takes place at the freez� ing point of -0.2 to -0.6°C (2). The density of the sea ice with no impurities is lower than in the Arctic Region and is ~920 kg/m (3). The ice temperature conditions strongly depend on the ambient air tem� perature. In typical conditions, the ice temperature is -1 to -2°C with homoeothermic distribution, while during long periods of -20°C frosts, the temperature

Fast ice distribution in Adélie Land, East Antarctica: interannual variability and implications for emperor penguins Aptenodytes forsteri

Antarctic fast ice is of key climatic and ecological importance, yet its distribution and variability are poorly understood. We present a detailed analysis of fast ice along the Adelie Land coast (East Antarctica) using satellite data from 1992 to 1999. Fast ice formation along this coastline is inti- mately linked to grounded iceberg distribution in waters of 75% success) coincided with lower-than-average fast ice extents and persistently short distances to nearest open water (foraging grounds), and corresponded to a strong positive phase of the Southern Annular Mode. Poor breeding seasons in 1992, 1994 and 1995 (success <15%) coin- cided with average to slightly higher-than-average ice extents and persistently long distances to forag- ing grounds. Poor-to-moderate breeding years (success ~40 to 50%), e.g. 1996 and 1997, occurred with above-average ice extents combined with fairly long distances from breeding to foraging grounds dur- ing the chick nurturing season. The overall correlation between breeding success and distance was high (r 2 = 0.89), albeit based on a limited number of years (n = 8). Substantially less fast ice was present in two Argon satellite photographs taken in August and October 1963. This coincided with a highly successful breeding season and appears to have been related to stronger and more southerly winds.

Modeling fast ice formation and destruction in the Sea of Japan

The problems of parametric representation of the initial formation and the subsequent evolution of fast ice in freezing seas are discussed within the framework of the model of marine ice cover evolution. The mathematical form of this representation takes into account the processes of transformation of sea ice formations in open water areas in coastal regions into fast ice during its formation and inverse processes at the stage of its destruction. The parametric identification of the model was based on samples of long-term distributions of ice cover characteristics in the Sea of Japan, as well as the distributions of air temperature and wind speeds over sea water area. The model can be used to predict the state of fast ice in the ice cover of the Sea of Japan.

Variability and climate sensitivity of fast ice extent in the north-eastern Kara Sea

This work investigates the temporal and spatial variation of shore-fast ice extent in the north-eastern part of the Kara Sea during 1953–1990 and its sensitivity to interannual variability of the regional climate. The area of fast ice in spring months shows a bimodal distribution. This indicates the existence of two different regimes of fast ice formation driven by the system of prevailing winds. The westward wind transport during the cold season gives larger fast ice extent while the eastward wind transport suppresses the expansion of fast ice. There is a significant correlation (ca. –0.55) between the average winter temperature and the area of fast ice. Linear trends for time records of shore-fast ice area in spring show a decrease during 1953–1990. This decrease is most pronounced in April: the mean fast ice area in April is 12 % lower in 1988–1990 compared to 1953–55. A comparison of fast ice regimes for two particular years— 1979 and 1985—revealed a significant influence of cyclone activity on fast ice development over the course of the cold season. It is shown that partial break-ups of fast ice in spring 1985 are associated with the passage of cyclones across the area of fast ice.

Ice Conditions along the Estonian Coast in a Statistical View

The paper presents the results from analysis of long-term (100-year) time series of freezing, fast ice formation, disappearance of fast ice, break-up and ice thickness for eight stations situated along the Estonian coast in the Gulf of Finland and Gulf of Riga. Most of the data have not been published yet. Basic statistics: average, standard deviation, maximum, minimum and frequency histograms are given. On average ice has formed in the Gulf of Finland three weeks later compared with the Gulf of Riga. The range of variation of the freezing date is very large, 3-4 months, with maximum value of standard deviation 29 days (Tallinn). The average ice seasons last 4-5 months; the range is 0- 7 months. Statistically significant trends are found in time series of date of freezing for Sõrve and Virtsu and in time series of ice break-up for Kihnu and Virtsu, both trends toward shorter ice seasons. Correlation coefficients of different time series are varied through 0.03-0.90.

Behaviour of ringed seals tagged with satellite transmitters in the North Water polynya during fast-ice formation

To gain insight into the use by ringed seals (Phoca hispida) of the North Water polynya (northern Baffin Bay), we monitored the movements and diving behaviour of eight ringed seals caught in the fjords of the Thule (Avernarsuaq) area in Northwest Greenland. The animals were caught in August-September 1996 and equipped with satellite transmitters. Contact with the seals was maintained for up to 146 days. Two of the seals left the study area soon after being equipped, one moved north to the Kane Basin and one moved to southeastern Baffin Island. The departure of the other six seals from the fjords was apparently related to the formation of landfast ice. After formation of the polynya, all positions were close to the edge of the fast ice in the Thule area. Of the six seals that stayed in the North Water, three females preferred areas with shallow water (&lt;100 m), while three males with larger body mass remained mainly in areas with deeper waters (&gt;100 m). The "shallow-water" seals dove significantly more frequently to depths of less than 50 m than the "deep-water" seals, whereas the deep-water seals made significantly more dives that were deeper than 50 m. However, all seals occasionally dove to depths of more than 250 m.