Landfast Sea Ice Break-up Processes in Admiralty Inlet, NU

Abstract. The floating ice shelves and glacier tongues which fringe the Antarctic continent are important because they help buttress ice flow from the ice sheet interior. Dynamic feedbacks associated with glacier calving have the potential to reduce buttressing and subsequently increase ice flow into the ocean. However, there are few high temporal resolution studies on glacier calving, especially in East Antarctica. Here we use ENVISAT ASAR wide swath mode imagery to investigate monthly glacier terminus change across six marine-terminating outlet glaciers in Porpoise Bay (76° S, 128° E), Wilkes Land (East Antarctica), between November 2002 and March 2012. This reveals a large near-simultaneous calving event in January 2007, resulting in a total of ∼  2900 km2 of ice being removed from glacier tongues. We also observe the start of a similar large near-simultaneous calving event in March 2016. Our observations suggest that both of these large calving events are driven by the break-up of the multi-year sea ice which usually occupies Porpoise Bay. However, these break-up events appear to have been driven by contrasting mechanisms. We link the 2007 sea ice break-up to atmospheric circulation anomalies in December 2005 weakening the multi-year sea ice through a combination of surface melt and a change in wind direction prior to its eventual break-up in January 2007. In contrast, the 2016 break-up event is linked to the terminus of Holmes (West) Glacier pushing the multi-year sea ice further into the open ocean, making the sea ice more vulnerable to break-up. In the context of predicted future warming and the sensitivity of sea ice to changes in climate, our results highlight the importance of interactions between landfast sea ice and glacier tongue stability in East Antarctica.

Download Full-text

The seasonal cycle and break-up of landfast sea ice along the northwest coast of Kotelny Island, East Siberian Sea

Journal of Glaciology ◽

10.1017/jog.2021.85 ◽

2021 ◽

pp. 1-13

Author(s):

Mengxi Zhai ◽

Bin Cheng ◽

Matti Leppäranta ◽

Fengming Hui ◽

Xinqing Li ◽

...

Keyword(s):

Sea Ice ◽

Seasonal Cycle ◽

Regional Climate ◽

Northwest Coast ◽

Ice Thickness ◽

East Siberian Sea ◽

Ice Fracturing ◽

Break Up ◽

Landfast Sea Ice ◽

Initial Freezing

Abstract Arctic landfast sea ice (LFSI) represents an important quasi-stationary coastal zone. Its evolution is determined by the regional climate and bathymetry. This study investigated the seasonal cycle and interannual variations of LFSI along the northwest coast of Kotelny Island. Initial freezing, rapid ice formation, stable and decay stages were identified in the seasonal cycle based on application of the visual inspection approach (VIA) to MODIS/Envisat imagery and results from a thermodynamic snow/ice model. The modeled annual maximum ice thickness in 1995–2014 was 2.02 ± 0.12 m showing a trend of −0.13 m decade−1. Shortened ice season length (−22 d decade−1) from model results associated with substantial spring (2.3°C decade−1) and fall (1.9°C decade−1) warming. LFSI break-up resulted from combined fracturing and melting, and the local spatiotemporal patterns of break-up were associated with the irregular bathymetry. Melting dominated the LFSI break-up in the nearshore sheltered area, and the ice thickness decreased to an average of 0.50 m before the LFSI disappeared. For the LFSI adjacent to drift ice, fracturing was the dominant process and the average ice thickness was 1.56 m at the occurrence of the fracturing. The LFSI stages detected by VIA were supported by the model results.

Download Full-text

Spectral albedo of coastal landfast sea ice in Prydz Bay, Antarctica

Journal of Glaciology ◽

10.1017/jog.2020.90 ◽

2020 ◽

pp. 1-11

Author(s):

Guanghua Hao ◽

Roberta Pirazzini ◽

Qinghua Yang ◽

Zhongxiang Tian ◽

Changwei Liu

Keyword(s):

Sea Ice ◽

Near Infrared ◽

Elevation Angle ◽

Early Summer ◽

Prydz Bay ◽

Katabatic Wind ◽

Surface Conditions ◽

Zhongshan Station ◽

Landfast Sea Ice ◽

Two Phases

Abstract The surface spectral albedo was measured over coastal landfast sea ice in Prydz Bay (off Zhongshan Station), East Antarctica from 5 October to 26 November of 2016. The mean albedo decreased from late-spring to early-summer, mainly responding to the change in surface conditions from dry (phase I) to wet (phase II). The evolution of the albedo was strongly influenced by the surface conditions, with alternation of frequent snowfall events and katabatic wind that induce snow blowing at the surface. The two phases and day-to-day albedo variability were more pronounced in the near-infrared albedo wavelengths than in the visible ones, as the near-infrared photons are more sensitive to snow metamorphism, and to changes in the uppermost millimeters and water content of the surface. The albedo diurnal cycle during clear sky conditions was asymmetric with respect to noon, decreasing from morning to evening over full and patchy snow cover, and decreasing more rapidly in the morning over bare ice. We conclude that snow and ice metamorphism and surface melting dominated over the solar elevation angle dependency in shaping the albedo evolution. However, we realize that more detailed surface observations are needed to clarify and quantify the role of the various surface processes.

Download Full-text

Seasonal evolution and salt/freshwater fluxes of first-year sea ice: Comparison between pack ice and landfast sea ice

10.5194/egusphere-egu21-10798 ◽

2021 ◽

Author(s):

Marc Oggier ◽

Hajo Eicken ◽

Robert Rember ◽

Allison Fong ◽

Dmitry V. Divine ◽

...

Keyword(s):

Sea Ice ◽

Ice Cores ◽

Upper Ocean ◽

First Year ◽

Ice Melt ◽

Ice Surface ◽

Freshwater Fluxes ◽

Exchange Processes ◽

Bulk Salinity ◽

Landfast Sea Ice

<p>Sea ice affects the exchange of energy and matter between the atmosphere and the ocean from local to hemispheric scales. Salt fluxes across the ice-ocean interface that drive thermohaline mixing beneath growing sea ice are important elements of upper ocean nutrient and carbon exchange. Sea-ice melt releases freshwater into the upper ocean and results in formation of melt ponds that affect gas and energy transfer across the atmosphere-ice interface. The Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) provided an opportunity to follow sea-ice evolution and exchange processes over a full seasonal cycle in a rapidly changing ice cover. To this end, approximately 25 sea-ice cores were collected at 2 distinct sites, representing first-year and multi-year ice, to monitor physical, biological and geochemical processes relevant to atmosphere-ice-ocean exchange processes. Here we compare the growth and decay of first-year ice in the Central Arctic during the winter 2019-2020 to that of landfast first-year ice at Utqia&#289;vik, Alaska, from 1998 to 2016. Ice stratigraphy was similar at both sites with about 15 cm of granular ice on top of columnar ice, with a comparable growth history with a similar maximum ice thickness of 1.6-1.7 m. We aggregated the sea-ice bulk salinity and temperature profiles using a degree-day approach, and examined brine and freshwater fluxes at lower and upper interfaces of the ice, respectively. Preliminary results show lower sea-ice bulk salinity during the growth season and greater desalination at the ice surface during the melt season at the MOSAiC floe in comparison to Utqia&#289;vik.</p>

Download Full-text

Physical controls on the storage of methane in landfast sea ice

The Cryosphere ◽

10.5194/tc-8-1019-2014 ◽

2014 ◽

Vol 8 (3) ◽

pp. 1019-1029 ◽

Cited By ~ 9

Author(s):

J. Zhou ◽

J.-L. Tison ◽

G. Carnat ◽

N.-X. Geilfus ◽

B. Delille

Keyword(s):

Sea Ice ◽

Bubble Formation ◽

Gas Bubble ◽

Physical Processes ◽

Ice Melt ◽

Physical Controls ◽

The Difference ◽

Landfast Sea Ice ◽

Ice Water ◽

Brine Concentration

Abstract. We report on methane (CH4) dynamics in landfast sea ice, brine and under-ice seawater at Barrow in 2009. The CH4 concentrations in under-ice water ranged from 25.9 to 116.4 nmol L−1sw, indicating a supersaturation of 700 to 3100% relative to the atmosphere. In comparison, the CH4 concentrations in sea ice ranged from 3.4 to 17.2 nmol L−1ice and the deduced CH4 concentrations in brine from 13.2 to 677.7 nmol L−1brine. We investigated the processes underlying the difference in CH4 concentrations between sea ice, brine and under-ice water and suggest that biological controls on the storage of CH4 in ice were minor in comparison to the physical controls. Two physical processes regulated the storage of CH4 in our landfast ice samples: bubble formation within the ice and sea ice permeability. Gas bubble formation due to brine concentration and solubility decrease favoured the accumulation of CH4 in the ice at the beginning of ice growth. CH4 retention in sea ice was then twice as efficient as that of salt; this also explains the overall higher CH4 concentrations in brine than in the under-ice water. As sea ice thickened, gas bubble formation became less efficient, CH4 was then mainly trapped in the dissolved state. The increase of sea ice permeability during ice melt marked the end of CH4 storage.

Download Full-text

Chlorophyll-a in Antarctic Landfast Sea Ice: A First Synthesis of Historical Ice Core Data

Journal of Geophysical Research Oceans ◽

10.1029/2018jc014245 ◽

2018 ◽

Vol 123 (11) ◽

pp. 8444-8459 ◽

Cited By ~ 11

Author(s):

K. M. Meiners ◽

M. Vancoppenolle ◽

G. Carnat ◽

G. Castellani ◽

B. Delille ◽

...

Keyword(s):

Sea Ice ◽

Chlorophyll A ◽

Ice Core ◽

Core Data ◽

Landfast Sea Ice

Download Full-text

Spatial variation of biogeochemical properties of landfast sea ice in the Gulf of Bothnia, Baltic Sea

Annals of Glaciology ◽

10.3189/172756406781811169 ◽

2006 ◽

Vol 44 ◽

pp. 80-87 ◽

Cited By ~ 15

Author(s):

M. Steffens ◽

M.A. Granskog ◽

H. Kaartokallio ◽

H. Kuosa ◽

K. Luodekari ◽

...

Keyword(s):

Sea Ice ◽

Baltic Sea ◽

Snow Depth ◽

Large Scale ◽

Spatial Scales ◽

Thick Layer ◽

Ice Cores ◽

Ice Thickness ◽

Gulf Of Bothnia ◽

Landfast Sea Ice

AbstractHorizontal variation of landfast sea-ice properties was studied in the Gulf of Bothnia, Baltic Sea, during March 2004. In order to estimate their variability among and within different spatial levels, 72 ice cores were sampled on five spatial scales (with spacings of 10 cm, 2.5 m, 25 m, 250m and 2.5 km) using a hierarchical sampling design. Entire cores were melted, and bulk-ice salinity, concentrations of chlorophylla(Chla), phaeophytin (Phaeo), dissolved nitrate plus nitrite (DIN) as well as dissolved organic carbon (DOC) and nitrogen (DON) were determined. All sampling sites were covered by a 5.5–23 cm thick layer of snow. Ice thicknesses of cores varied from 26 to 58 cm, with bulk-ice salinities ranging between 0.2 and 0.7 as is typical for Baltic Sea ice. Observed values for Chla(range: 0.8–6.0 mg ChlaL–1; median: 2.9 mg ChlaL–1) and DOC (range: 37–397 μM; median: 95 μM) were comparable to values reported by previous sea-ice studies from the Baltic Sea. Analysis of variance among different spatial levels revealed significant differences on the 2.5km scale for ice thickness, DOC and Phaeo (with the latter two being positively correlated with ice thickness). For salinity and Chla, the 250 m scale was found to be the largest scale where significant differences could be detected, while snow depth only varied significantly on the 25 m scale. Variability on the 2.5 m scale contributed significantly to the total variation for ice thickness, salinity, Chlaand DIN. In the case of DON, none of the investigated levels exhibited variation that was significantly different from the considerable amount of variation found between replicate cores. Results from a principal component analysis suggest that ice thickness is one of the main elements structuring the investigated ice habitat on a large scale, while snow depth, nutrients and salinity seem to be of secondary importance.

Download Full-text

The Ice of Crown Prince Gustav Channel, Graham Land, Antarctica

Journal of Glaciology ◽

10.1017/s0022143000012703 ◽

1950 ◽

Vol 1 (08) ◽

pp. 404-409 ◽

Cited By ~ 18

Author(s):

Alan Reece

Keyword(s):

Sea Ice ◽

East Coast ◽

Falkland Islands ◽

Northern Half ◽

Southern Half ◽

Landfast Sea Ice ◽

Crown Prince

The author describes the ice in Crown Prince Gustav Channel on the east coast of Graham Land, Antarctica, based mainly on observations made by members of the Falkland Islands Dependencies Survey in 1945–48. He considers that the ice in the northern half of the Channel is landfast sea ice which may persist for more than one season, and, that in the southern half it is shelf ice of the same origin as the Larsen Shelf Ice. He concludes that this shelf ice in the southern part of the Channel is part of the Larsen Shelf Ice.

Download Full-text