Retrogressive thaw slumps in areas with tabular ground ice on Kolguev (Barents Sea) and Novaya Sibir’ (East-Siberian Sea) Islands

2020 ◽  
Author(s):  
Alexander Kizyakov ◽  
Frank Günther ◽  
Mikhail Zimin ◽  
Anton Sonyushkin ◽  
Ekaterina Zhdanova ◽  
...  
Keyword(s):  
Sea Ice ◽  
Air Temperature ◽  
Linear Trend ◽  
Open Water ◽  
Wave Action ◽  
Observation Data ◽  
Ground Ice ◽  
Significant Linear Trend ◽  
Ice Conditions ◽  
Kolguev Island

<p>The activation of retrogressive thaw slumps is associated with slope surface stability disturbances, or with an increase in the depth of seasonal thawing, that can reach the top of surface-near ground ice. Most retrogressive thaw slumps are confined to terraced slope surfaces that have been undercut and started to retreat due to lateral river erosion or wave action along lake, river or sea shores. Subsequent long-term retrogressive that slump growth depends on constant removal of material from the slope foot by river water or sea waves.</p><p>We have studied the current dynamics of coastal destruction and retrogressive thaw slumps in the western (Kolguev Island) and one of the eastern-most (Novaya Sibir’ Island) occurrences of tabular ground ice in the Eurasian Arctic. A wide set of multi-temporal optical earth observation data of high and very-high spatial resolution (SPOT 6 & 7, GeoEye, WorldView, Kompsat, Prism, Formosat, and Resurs) was used. We modified the TanDEM-X DEM (12 m) for relief reconstruction of earlier stage relief settings to ensure consistent orthorectification of oblique viewing satellite imagery. All raw images were terrain-corrected and georeferenced using a comprehensive block adjustment.</p><p>In the western part of Kolguev Island retrogressive thaw slump average retreat rates of different thermocirque features varied from 0.7 to 7.9 m/year in 2002-2018. Maximum rates reached 14.5-15.1 m/year. On the Novaya Sibir’ Island thermocirques averaged retreat rates in 2007-2018 varied from 3.3 to 8.5 m/year, maximum rates were up to 15.5 m/year.</p><p>Besides dependence of thermocirque occurrence on local ground ice conditions, external forcing on coastal dynamics and thermocirque retreat has been analysed for air temperature and sea ice fluctuations through sums of positive daily mean air temperature and the duration of the open-water period variability for specific periods bracketed by image acquisition dates. Ice conditions in the coastal zone (app. near 50 km of coastal line) of the studied areas were analyzed according to microwave satellite OSI-450 and OSI-430 datasets. We assumed the open-water season as the period when sea ice concentration was less than 15%. Around Kolguev Island, over the 2006-2018 there has been not statistically significant linear trend for open-water period - median value of linear trend is 2.5 days/year with different sea ice conditions off the south and north coasts of the island. At the same time, an increase in the annual sum of positive daily mean  air temperature is noted. For the period 2006-2018, the linear trend was 23.2 degree/year. That is why, for Kolguev Island, we expect at least a sustained level of substantially stronger retreat rates when compared with the past, if not a further increase in thermal denudation intensity and thermocirque growth, and strong and steady rates of coastal destruction due to wave action. Further research will focus on identifying commonalities and differences between the two study regions with respect to hydrometeorological and permafrost conditions.</p><p>Supported by RFBR grants № 18-05-60080 and 18-05-60221, and by DFG grant № WE4390/7-1.</p>

scholarly journals Observing Muostakh disappear: permafrost thaw subsidence and erosion of a ground-ice-rich island in response to arctic summer warming and sea ice reduction

2015 ◽  
Vol 9 (1) ◽  
pp. 151-178 ◽  
Author(s):  
F. Günther ◽  
P. P. Overduin ◽  
I. A. Yakshina ◽  
T. Opel ◽  
A. V. Baranskaya ◽  
...  
Keyword(s):  
Sea Ice ◽  
Air Temperature ◽  
Open Water ◽  
Aerial Photographs ◽  
The Arctic ◽  
Interannual Variations ◽  
Ground Ice ◽  
Concentration Data ◽  
Water Fraction ◽  
Permafrost Thaw

Abstract. Observations of coastline retreat using contemporary very high resolution satellite and historical aerial imagery were compared to measurements of open water fraction, summer air temperature, and wind. We analysed seasonal and interannual variations of thawing-induced cliff top retreat (thermo-denudation) and marine abrasion (thermo-abrasion) on Muostakh Island in the southern central Laptev Sea. Geomorphometric analysis revealed that total ground ice content on Muostakh is made up of equal amounts of intrasedimentary and macro ground ice and sums up to 87%, rendering the island particularly susceptible to erosion along the coast, resulting in land loss. Based on topographic reference measurements during field campaigns, we generated digital elevation models using stereophotogrammetry, in order to block-adjust and orthorectify aerial photographs from 1951 and GeoEye, QuickBird, WorldView-1, and WorldView-2 imagery from 2010 to 2013 for change detection. Using sea ice concentration data from the Special Sensor Microwave Imager (SSM/I) and air temperature time series from nearby Tiksi, we calculated the seasonal duration available for thermo-abrasion, expressed as open water days, and for thermo-denudation, based on the number of days with positive mean daily temperatures. Seasonal dynamics of cliff top retreat revealed rapid thermo-denudation rates of −10.2 ± 4.5 m a−1 in mid-summer and thermo-abrasion rates along the coastline of −3.4 ± 2.7 m a−1 on average during the 2010–2013 observation period, currently almost twice as rapid as the mean rate of −1.8 ± 1.3 m a−1 since 1951. Our results showed a close relationship between mean summer air temperature and coastal thermo-erosion rates, in agreement with observations made for various permafrost coastlines different to the East Siberian Ice Complex coasts elsewhere in the Arctic. Seasonality of coastline retreat and interannual variations of environmental factors suggest that an increasing length of thermo-denudation and thermo-abrasion process simultaneity favours greater coastal erosion. Coastal thermo-erosion has reduced the island's area by 0.9 km2 (24%) over the past 62 years but shrank its volume by 28 x 106 m3 (40%), not least because of permafrost thaw subsidence, with the most pronounced with rates of ≥− 11 cm a−1 on yedoma uplands near the island's rapidly eroding northern cape. Recent acceleration in both will halve Muostakh Island's lifetime to less than a century.

scholarly journals Observing Muostakh Island disappear: erosion of a ground-ice-rich coast in response to summer warming and sea ice reduction on the East Siberian shelf

2013 ◽  
Vol 7 (4) ◽  
pp. 4101-4176 ◽  
Author(s):  
F. Günther ◽  
P. P. Overduin ◽  
A. Baranskaya ◽  
T. Opel ◽  
M. N. Grigoriev
Keyword(s):  
Sea Ice ◽  
Air Temperature ◽  
Open Water ◽  
The Arctic ◽  
Historical Period ◽  
Interannual Variations ◽  
Ground Ice ◽  
Concentration Data ◽  
Sea Ice Concentration ◽  
Ice Complex

Abstract. Observations of coastline retreat using contemporary very high resolution satellite and historical aerial imagery were compared to measurements of open water fractions and summer air temperatures. We analyzed seasonal and interannual variations of thawing-induced cliff top retreat (thermo-denudation) and marine abrasion (thermo-abrasion) on Muostakh Island in the southern central Laptev Sea. The island is composed of ground-ice-rich permafrost deposits of Ice Complex type that render it particularly susceptible to erosion along the coast, resulting in land loss. Based on topographic reference measurements during field campaigns, we generated digital elevation models using stereophotogrammetry, in order to block adjust and ortho-rectify aerial photographies from 1951 and GeoEye, QuickBird, WorldView-1, and WorldView-2 imagery from 2010 to 2012 for change detection. Coastline retreat for erosive segments ranged from −13 to −585 m and was −109 ± 81 m (–1.8 ± 1.3 m a−1) on average during the historical period. Current seasonal dynamics of cliff top retreat revealed rapid thermo-denudation rates of –10.2 ± 4.5 m a−1 in mid summer and –4.1 ± 2.0 m a−1 on average during the 2010–2012 observation period. Using sea ice concentration data from the Special Sensor Microwave Imager (SSM/I) and air temperature time series from Tiksi, we calculated seasonal duration available for thermo-abrasion, expressed as open water days, and for thermo-denudation, based on thawing degree days. Geomorphometric analysis revealed that total ground ice content on Muostakh is made up of equal amounts of intrasedimentary and macro ground ice, while its vertical hourglass distribution provides favorable local preconditions for subsidence and the acceleration of coastal thermo-erosion under intensifying environmental forcings. Our results showed a~close relationship between mean summer air temperature and coastal thermo-erosion rates, in agreement with observations made for various permafrost coastlines different from East Siberian Ice Complex coasts elsewhere in the Arctic. Seasonality and recent interannual variations of coastline retreat rates suggest that the combination of macro ground ice distribution in the ground and changes in enviromental forcing generate a cyclicity in coastal thermo-erosion, that is currently increasing in frequency.

scholarly journals Using RADARSAT to Identify Sea Ice Ridges and their Implications for Shipping in Canada’s Hudson Strait

ARCTIC ◽  
2016 ◽  
Vol 69 (4) ◽  
pp. 421 ◽  
Author(s):  
Olivia Mussells ◽  
Jackie Dawson ◽  
Stephen Howell
Keyword(s):  
Sea Ice ◽  
Linear Trend ◽  
The Arctic ◽  
Storm Events ◽  
Ridge Count ◽  
Significant Linear Trend ◽  
The North ◽  
Ice Conditions ◽  
A Site ◽  
Annual Scale

Ridges in sea ice and the convergent forces that form them are a serious hazard to ships traveling in the Arctic, but few studies have examined ridge distribution at a basin level in the Canadian Arctic. The Hudson Strait, which connects Hudson Bay and the North Atlantic, is a site of ongoing winter shipping where vessels frequently encounter pressured ice conditions and ridging. Here, RADARSAT-1 and RADARSAT-2 ScanSAR Wide images were used to identify ridges manually in a winter shipping corridor in the Hudson Strait for the period 1997 to 2012. Ridge count peaked in the month of March. No significant linear trend in the number of ridges was identified on either a monthly or annual scale, which is the result of great variability from year to year. However, spatial patterns of ridging distribution were evident: ridging occurred primarily in the eastern and western sectors of the study area, both in the region between Charles Island and the Quebec coastline and at the eastern entrance to the Hudson Strait. Seasonal sea level pressure (SLP) patterns from years of high and low ridge density were compared, but consistent correlations between SLP and ridge density were not found. The impacts of one-time storm events on ridge densities were also investigated. More analysis is needed to understand the factors influencing ridge density in the Hudson Strait.

scholarly journals Long-distance swimming by polar bears (Ursus maritimus) of the southern Beaufort Sea during years of extensive open water

2012 ◽  
Vol 90 (5) ◽  
pp. 663-676 ◽  
Author(s):  
A.M. Pagano ◽  
G.M. Durner ◽  
S.C. Amstrup ◽  
K.S. Simac ◽  
G.S. York
Keyword(s):  
Sea Ice ◽  
Adult Female ◽  
Open Water ◽  
Ursus Maritimus ◽  
Polar Bears ◽  
Long Distance ◽  
Gps Collars ◽  
Movement Data ◽  
Global Positioning ◽  
Ice Conditions

Polar bears ( Ursus maritimus Phipps, 1774) depend on sea ice for catching marine mammal prey. Recent sea-ice declines have been linked to reductions in body condition, survival, and population size. Reduced foraging opportunity is hypothesized to be the primary cause of sea-ice-linked declines, but the costs of travel through a deteriorated sea-ice environment also may be a factor. We used movement data from 52 adult female polar bears wearing Global Positioning System (GPS) collars, including some with dependent young, to document long-distance swimming (>50 km) by polar bears in the southern Beaufort and Chukchi seas. During 6 years (2004–2009), we identified 50 long-distance swims by 20 bears. Swim duration and distance ranged from 0.7 to 9.7 days (mean = 3.4 days) and 53.7 to 687.1 km (mean = 154.2 km), respectively. Frequency of swimming appeared to increase over the course of the study. We show that adult female polar bears and their cubs are capable of swimming long distances during periods when extensive areas of open water are present. However, long-distance swimming appears to have higher energetic demands than moving over sea ice. Our observations suggest long-distance swimming is a behavioral response to declining summer sea-ice conditions.

The Weddell Sea Expedition 2019

2020 ◽  
Author(s):  
John Shears ◽  
Julian Dowdeswell ◽  
Freddie Ligthelm ◽  
Paul Wachter
Keyword(s):  
Sea Ice ◽  
Autonomous Underwater Vehicles ◽  
Remote Sensing Data ◽  
Open Water ◽  
Weddell Sea ◽  
Scientific Programme ◽  
Ice Shelf ◽  
Remotely Operated Vehicle ◽  
Radar Images ◽  
Ice Conditions

<p>The Weddell Sea Expedition 2019 (WSE) was conceived with dual aims: (i) to undertake a comprehensive international inter-disciplinary programme of science centred in the waters around Larsen C Ice Shelf, western Weddell Sea; and (ii) to search for, survey and image the wreck of Sir Ernest Shackleton’s Endurance, which sank in the Weddell Sea in 1915. </p><p>The 6-week long expedition, funded by the Flotilla Foundation, required the use of a substantial ice-strengthened vessel given the very difficult sea-ice conditions encountered in the Weddell Sea, and especially in its central and western parts. The South African ship SA Agulhas II was chartered for its Polar Class 5 icebreaking capability and design as a scientific research vessel. The expedition was equipped with state-of-the-art Autonomous Underwater Vehicles (AUVs) and a Remotely Operated Vehicle (ROV) which were capable of deployment to waters more than 3,000 m deep, thus making the Larsen C continental shelf and slope, and the Endurance wreck site, accessible. During the expedition, a suite of passive and active remote-sensing data, including TerraSAR-X radar images delivered in near real-time, was provided to the ice-pilot onboard the SA Agulhas II. These data were instrumental for safe vessel navigation in sea ice and the detection and tracking of icebergs and ice floes of scientific interest.</p><p>The scientific programme undertaken by the WSE was very successful and produced many new geological, geophysical, marine biological and oceanographic observations from a part of the Weddell Sea that has been little studied previously, particularly the area east of Larsen C Ice Shelf. The expedition also reached the sinking location of Shackleton’s Endurance, where the presence of open-water sea ice leads allowed the deployment of an AUV to the ocean floor to try and locate and survey the wreck. Unfortunately, SA Agulhas II later lost communication with the AUV, and deteriorating weather and sea ice conditions meant that the search had to be called off.</p>

Unusual Predation Attempts of Polar Bears on Ringed Seals in the Southern Beaufort Sea: Possible Significance of Changing Spring Ice Conditions

ARCTIC ◽  
2009 ◽  
Vol 61 (1) ◽  
pp. 14 ◽  
Author(s):  
Ian Stirling ◽  
Evan Richardson ◽  
Gregory W. Thiemann ◽  
Andrew E. Derocher
Keyword(s):  
Sea Ice ◽  
Polar Bear ◽  
Foraging Behaviour ◽  
Open Water ◽  
Beaufort Sea ◽  
Polar Bears ◽  
Ringed Seals ◽  
Decadal Scale ◽  
Underlying Causes ◽  
Ice Conditions

In April and May 2003 through 2006, unusually rough and rafted sea ice extended for several tens of kilometres offshore in the southeastern Beaufort Sea from about Atkinson Point to the Alaska border. Hunting success of polar bears (Ursus maritimus) seeking seals was low despite extensive searching for prey. It is unknown whether seals were less abundant in comparison to other years or less accessible because they maintained breathing holes below rafted ice rather than snowdrifts, or whether some other factor was involved. However, we found 13 sites where polar bears had clawed holes through rafted ice in attempts to capture ringed seals (Phoca hispida) in 2005 through 2006 and another site during an additional research project in 2007. Ice thickness at the 12 sites that we measured averaged 41 cm. These observations, along with cannibalized and starved polar bears found on the sea ice in the same general area in the springs of 2004 through 2006, suggest that during those years, polar bears in the southern Beaufort Sea were nutritionally stressed. Searches made farther north during the same period and using the same methods produced no similar observations near Banks Island or in Amundsen Gulf. A possible underlying ecological explanation is a decadal-scale downturn in seal populations. But a more likely explanation is major changes in the sea-ice and marine environment resulting from record amounts and duration of open water in the Beaufort and Chukchi seas, possibly influenced by climate warming. Because the underlying causes of observed changes in polar bear body condition and foraging behaviour are unknown, further study is warranted.

Human geographies of sea ice: freeze/thaw processes around Cape Dorset, Nunavut, Canada

Polar Record ◽  
2008 ◽  
Vol 44 (1) ◽  
pp. 51-76 ◽  
Author(s):  
Gita J. Laidler ◽  
Pootoogoo Elee
Keyword(s):  
Sea Ice ◽  
Regional Scale ◽  
Open Water ◽  
Current Strength ◽  
Ice Formation ◽  
Future Research ◽  
Baffin Island ◽  
Freeze Thaw ◽  
Ice Conditions ◽  
Inuit Knowledge

ABSTRACTSea ice has been, and continues to be, an integral component of life in the Inuit community of Cape Dorset, Nunavut. Located on an island of the same name off the southwestern coast of Baffin Island, the strong Hudson Strait currents prevent extensive ice formation around the community. Nevertheless, sea ice remains an important travel and hunting platform, enabling access to Baffin Island, hunting and fishing grounds, and nearby communities. With the combined importance, dynamism, and continuous use of this frozen ocean environment, local Inuit elders and hunters have developed a detailed and nuanced understanding of sea ice conditions, freeze/thaw processes, and the influences of winds and currents on ice conditions. Working collaboratively with the community of Cape Dorset since October, 2003, we present the results of 30 semi-directed interviews, 5 sea ice trips, and 2 focus groups to provide a baseline understanding of local freezing processes (near-shore, open water, sea ice thickening, landfast ice, floe edge, and tidal cracks), melting processes (snow melt, water accumulation and drainage, break-up, and cracks/leads), wind influences on sea ice (wind direction and strength affecting sea ice formation, and movement), and current influences on sea ice (tidal variations and current strength affecting sea ice formation, movement, and polynya size/location). Strong emphasis is placed on Inuktitut terminology and spatial delineations of localised ice conditions and features. Therefore, this paper provides insights into local scale ice conditions and dynamics around Cape Dorset that are not captured in regional scale studies of Hudson Bay and/or Hudson Strait. Results have the potential to inform future research efforts on local/regional sea ice monitoring, the relationship between Inuit knowledge, language, and the environment, and addressing community interests through targeted studies.

scholarly journals The importance of capturing late melt season sea ice conditions for modeling the western Arctic ocean boundary layer

Elem Sci Anth ◽  
2019 ◽  
Vol 7 ◽  
Author(s):  
Shawn G. Gallaher
Keyword(s):  
Boundary Layer ◽  
Sea Ice ◽  
Late Summer ◽  
Open Water ◽  
Heat Fluxes ◽  
Conductive Heat ◽  
Near Surface ◽  
Ice Conditions ◽  
Western Arctic ◽  
Ocean Boundary

To better understand the response of the western Arctic upper ocean to late summer ice-ocean interactions, a range of surface, interior, and basal sea ice conditions were simulated in a 1-D turbulent boundary layer model. In-ice and under-ice autonomous observations from the 2014 Marginal Ice Zone Experiment provided a complete characterization of the late melt-season sea ice and were used to set initial conditions, update boundary conditions, and conduct model validation studies. Results show that underestimates of open water and melt pond fraction at the sea ice surface had the largest influence on ocean-to-ice turbulent heat fluxes reducing basal melt rates by as much as 32%. This substantial reduction in latent heat loss was attributed to underestimates of open water areas and the exclusion of melt ponds by low-resolution synthetic aperture radar imagery. However, the greatest overall effect on the ice-ocean boundary layer came from mischaracterizations of basal roughness, with smooth ice scenarios resulting in 7 m of summer halocline shoaling and preservation of the near-surface temperature maximum. Rough ice conditions showed a 23% deepening of the mixed layer and erosion of heat storage above 40 m. Adjustments of conductive heat fluxes had little effect on the near-interface heat budget due to small internal thermal gradients within the late summer sea ice. Results from the 1-D boundary layer simulations highlight the most influential components of sea ice structure during late summer conditions and provide the magnitude of errors expected when ice conditions are mischaracterized.

scholarly journals Winter Sea-ice mapping from multi-parameter synthetic-aperture radar data

1994 ◽  
Vol 40 (134) ◽  
pp. 31-45 ◽  
Author(s):  
Eric Rignot ◽  
Mark R. Drinkwater
Keyword(s):  
Sea Ice ◽  
Classification Accuracy ◽  
Open Water ◽  
Radar Data ◽  
Single Frequency ◽  
First Year ◽  
Synthetic Aperture Radar Data ◽  
Ice Conditions ◽  
L Band ◽  
Single Polarization

AbstractThe limitations of current and immediate future single-frequency, single-polarization, space-borne SARs for winter sea-ice mapping are quantitatively examined, and improvements are suggested by combining frequencies and polarizations. Ice-type maps are generated using multi-channel, air-borne SAR observations of winter sea ice in the Beaufort Sea to identify six ice conditions: (1) multi-year sea ice; (2) compressed first-year ice; (3) first-year rubble and ridges; (4) first-year rough ice; (5) first-year smooth ice; and (6) first-year thin ice. At a single polarization, C- (λ = 5.6 cm) and L- (λ = 24 cm) band frequencies yield a classification accuracy of 67 and 71%, because C-band confuses multi-year ice and compressed, rough, thick first-year ice surrounding multi-year ice floes, and L-band confuses multi-year ice and deformed first-year ice. Combining C- and L-band improves classification accuracy by 20%. Adding a second polarization at one frequency only improves classification accuracy by 10–14% and separates thin ice and calm open water. Under similar winter-ice conditions, ERS-1 (Cvv) and Radarsat (CHH) would overestimate the multi-year ice fraction by 15% but correctly map the spatial variability of ice thickness; J-ERS-1 (LHH) would perform poorly;and J-ERS-1 combined with ERS-1 or Radarsat would yield reliable estimates of the old, thick, first-year and thin-ice fractions, and of the spatial distribution of ridges. With two polarizations, future single-frequency space-borne SARs could improve our current capability to discriminate thinner ice types.

scholarly journals Automated Underway Eddy Covariance System for Air–Sea Momentum, Heat, and CO2 Fluxes in the Southern Ocean

2016 ◽  
Vol 33 (4) ◽  
pp. 635-652 ◽  
Author(s):  
Brian J. Butterworth ◽  
Scott D. Miller
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Eddy Covariance ◽  
Open Water ◽  
Ice Cover ◽  
Published Data ◽  
Flow Distortion ◽  
Ice Conditions ◽  
Antarctic Research ◽  
Processing Techniques

AbstractA ruggedized closed-path eddy covariance (EC) system was designed for unattended direct measurements of air–sea momentum, heat, and CO2 flux, and was deployed on the Research Vessel Icebreaker (RV/IB) Nathaniel B. Palmer (NBP), an Antarctic research and supply vessel. The system operated for nine cruises during 18 months from January 2013 to June 2014 in the Southern Ocean and coastal Antarctica, sampling a wide variety of wind, wave, biological productivity, and ice conditions. The methods are described and the results are shown for two cruises chosen for their latitudinal range, inclusion of both open water and sea ice cover, and relatively large air–water CO2 concentration differences (ΔpCO2). Ship flow distortion was addressed by comparing mean winds, fluxes, and cospectra from an array of 3D anemometers at the NBP bow, comparing measured fluxes with bulk formulas, and implementing and evaluating several recently published data processing techniques. Quality-controlled momentum, heat, and CO2 flux data were obtained for 25% of the periods when NBP was at sea, with most (86%) of the rejected periods due to wind directions relative to the ship >±30° from the bow. In contrast to previous studies, no bias was apparent in measured CO2 fluxes for low |ΔpCO2|. The relationship between momentum flux and wind speed showed a clear dependence on the degree of sea ice cover, a result facilitated by the geographical coverage possible with a ship-based approach. These results indicate that ship-based unattended EC in high latitudes is feasible, and recommendations for deployments of underway systems in such environments are provided.

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