scholarly journals Eddies in the Marginal Ice Zone of Fram Strait and Svalbard from Spaceborne SAR Observations in Winter

2021 ◽  
Vol 14 (1) ◽  
pp. 134
Author(s):  
Igor E. Kozlov ◽  
Oksana A. Atadzhanova
Keyword(s):  
Sea Ice ◽  
Fram Strait ◽  
Sar Images ◽  
Mean Values ◽  
Envisat Asar ◽  
Ice Melt ◽  
Ice Concentration ◽  
Marginal Ice Zone ◽  
Eddy Generation ◽  
Ice Edge

Here we investigate the intensity of eddy generation and their properties in the marginal ice zone (MIZ) regions of Fram Strait and around Svalbard using spaceborne synthetic aperture radar (SAR) data from Envisat ASAR and Sentinel-1 in winter 2007 and 2018. Analysis of 2039 SAR images allowed identifying 4619 eddy signatures. The number of eddies detected per image per kilometer of MIZ length is similar for both years. Submesoscale and small mesoscale eddies dominate with cyclones detected twice more frequently than anticyclones. Eddy diameters range from 1 to 68 km with mean values of 6 km and 12 km over shallow and deep water, respectively. Mean eddy size grows with increasing ice concentration in the MIZ, yet most eddies are detected at the ice edge and where the ice concentration is below 20%. The fraction of sea ice trapped in cyclones (53%) is slightly higher than that in anticyclones (48%). The amount of sea ice trapped by a single ‘mean’ eddy is about 40 km2, while the average horizontal retreat of the ice edge due to eddy-induced ice melt is about 0.2–0.5 km·d–1 ± 0.02 km·d–1. Relation of eddy occurrence to background currents and winds is also discussed.

scholarly journals Eddy generation and variability of the marginal ice zone in the Fram Strait according to satellite radar measurements

2021 ◽  
Vol 2057 (1) ◽  
pp. 012022
Author(s):  
L A Petrenko ◽  
I E Kozlov
Keyword(s):  
Synthetic Aperture ◽  
Spatial And Temporal Variability ◽  
Fram Strait ◽  
Marginal Ice Zone ◽  
Eddy Generation ◽  
Radar Measurements ◽  
Ice Edge ◽  
Satellite Radar ◽  
Edge Displacement ◽  
Ice Water

Abstract Based on analysis of spaceborne synthetic aperture data (SAR), acquired in summer of 2007 over Fram Strait and around Svalbard, we investigate spatial and temporal variability of the ice edge and generation of eddies in the marginal ice zone. During the season, the ice-water boundary nonuniformly moves along its entire length with the overall width of the ice edge displacement ranging from 30 to 220 km. The ice edge movement is often accompanied by generation of eddies and filaments peaking in August. Analysis of the data serves to find out over 2000 distinct MIZ eddies with a clear dominance of cyclones (78%). In July the detected eddies are predominantly formed along the ice edge, in August most of them are generated inside the MIZ, while in September their numbers along the ice edge and within the MIZ are similar. Larger eddies (10-20 km in diameter) are found over deep Fram Strait and the Greenland Sea shelf, while smaller eddies (~5 km) are observed in coastal regions around Svalbard.

scholarly journals The interplay of dynamic and thermodynamic processes in driving the ice-edge location in the Southern Ocean

2011 ◽  
Vol 52 (57) ◽  
pp. 27-34 ◽  
Author(s):  
R.P. Stevens ◽  
P. Heil
Keyword(s):  
Sea Ice ◽  
Air Temperature ◽  
Freezing Point ◽  
Ice Growth ◽  
Ice Melt ◽  
Ice Concentration ◽  
Edge Location ◽  
Ice Edge ◽  
Ice Production ◽  
Thermodynamic Processes

AbstractA stand-alone sea-ice model (CICE4) was used to investigate the physical processes affecting the ice-edge location. Particular attention is paid to the relative contributions of dynamic and thermodynamic processes in advancing the ice edge equatorward during ice growth. Results from 10 years of an 11 year numerical simulation have been verified against satellite observations from 1998 to 2007. the autumn advance of the sea-ice edge is primarily due to thermodynamic processes, with significant dynamic contributions limited to regions such as 60–70˚ E and 310–340˚ E. In the dynamically dominated regions, winds with a southerly component cause equatorward ice advection but also induce thermodynamic growth of new ice, which occurs well poleward of the 15% ice-concentration contour where air temperature is lowest. As the ice moves into warmer water it melts, hence extending equatorward the region with ocean mixed layer at freezing point. This accelerates the northward progression of the ice edge and permits thermodynamic ice growth as soon as the air temperature reaches below the ocean freezing point. In regions where thermodynamic processes are dominant (e.g. 340–40˚ E), maximum ice production occurs just poleward of the 15% ice-concentration contour, where thin sea ice is prevalent. In these longitude bands, autumn ice melt is generally absent at the ice edge due to ineffective equatorward ice advection.

scholarly journals Operational SAR-based sea ice drift monitoring over the Baltic Sea

Ocean Science ◽  
2012 ◽  
Vol 8 (4) ◽  
pp. 473-483 ◽  
Author(s):  
J. Karvonen
Keyword(s):  
Sea Ice ◽  
Baltic Sea ◽  
Vector Fields ◽  
Phase Correlation ◽  
The Baltic Sea ◽  
Sar Images ◽  
Envisat Asar ◽  
Ice Drift ◽  
Sea Ice Drift ◽  
The Baltic

Abstract. An algorithm for computing ice drift from pairs of synthetic aperture radar (SAR) images covering a common area has been developed at FMI. The algorithm has been developed based on the C-band SAR data over the Baltic Sea. It is based on phase correlation in two scales (coarse and fine) with some additional constraints. The algorithm has been running operationally in the Baltic Sea from the beginning of 2011, using Radarsat-1 ScanSAR wide mode and Envisat ASAR wide swath mode data. The resulting ice drift fields are publicly available as part of the MyOcean EC project. The SAR-based ice drift vectors have been compared to the drift vectors from drifter buoys in the Baltic Sea during the first operational season, and also these validation results are shown in this paper. Also some navigationally useful sea ice quantities, which can be derived from ice drift vector fields, are presented.

scholarly journals The Response of the Nordic Seas to Wintertime Sea-ice Retreat

2021 ◽  
pp. 1-40
Author(s):  
Yue Wu ◽  
David P. Stevens ◽  
Ian A. Renfrew ◽  
Xiaoming Zhai
Keyword(s):  
Global Warming ◽  
Sea Ice ◽  
Climate Model ◽  
Sea Temperature ◽  
Nordic Seas ◽  
Ocean Response ◽  
Marginal Ice Zone ◽  
Ice Retreat ◽  
Ice Edge ◽  
Sea Ice Retreat

AbstractThe ocean response to wintertime sea-ice retreat is investigated in the coupled climate model HiGEM. We focus on the marginal ice zone and adjacent waters of the Nordic Seas, where the air-sea temperature difference can be large during periods of off-ice winds promoting high heat flux events. Both control and transient climate model ensembles are examined, which allows us to isolate the ocean response due to sea-ice retreat from the response due to climate change. As the wintertime sea-ice edge retreats towards the Greenland coastline, it exposes waters that were previously covered by ice which enhances turbulent heat loss and mechanical mixing, leading to a greater loss of buoyancy and deeper vertical mixing in this location. However, under global warming, the buoyancy loss is inhibited as the atmosphere warms more rapidly than the ocean which reduces the air-sea temperature difference. This occurs most prominently further away from the retreating ice edge, over the Greenland Sea gyre. Over the gyre the upper ocean also warms significantly, resulting in a more stratified water column and, as a consequence, a reduction in the depth of convective mixing. In contrast, closer to the coast the effect of global warming is overshadowed by the effect of the sea-ice retreat, leading to significant changes in ocean temperature and salinity in the vicinity of the marginal ice zone.

scholarly journals Changes of the Arctic marginal ice zone during the satellite era

2020 ◽  
Vol 14 (6) ◽  
pp. 1971-1984 ◽  
Author(s):  
Rebecca J. Rolph ◽  
Daniel L. Feltham ◽  
David Schröder
Keyword(s):  
Sea Ice ◽  
Arctic Sea Ice ◽  
Satellite Observations ◽  
The Arctic ◽  
Upper And Lower Bounds ◽  
Sea Ice Concentration ◽  
Sea Ice Extent ◽  
Ice Concentration ◽  
Marginal Ice Zone ◽  
Definition Of

Abstract. Many studies have shown a decrease in Arctic sea ice extent. It does not logically follow, however, that the extent of the marginal ice zone (MIZ), here defined as the area of the ocean with ice concentrations from 15 % to 80 %, is also changing. Changes in the MIZ extent has implications for the level of atmospheric and ocean heat and gas exchange in the area of partially ice-covered ocean and for the extent of habitat for organisms that rely on the MIZ, from primary producers like sea ice algae to seals and birds. Here, we present, for the first time, an analysis of satellite observations of pan-Arctic averaged MIZ extent. We find no trend in the MIZ extent over the last 40 years from observations. Our results indicate that the constancy of the MIZ extent is the result of an observed increase in width of the MIZ being compensated for by a decrease in the perimeter of the MIZ as it moves further north. We present simulations from a coupled sea ice–ocean mixed layer model using a prognostic floe size distribution, which we find is consistent with, but poorly constrained by, existing satellite observations of pan-Arctic MIZ extent. We provide seasonal upper and lower bounds on MIZ extent based on the four satellite-derived sea ice concentration datasets used. We find a large and significant increase (>50 %) in the August and September MIZ fraction (MIZ extent divided by sea ice extent) for the Bootstrap and OSI-450 observational datasets, which can be attributed to the reduction in total sea ice extent. Given the results of this study, we suggest that references to “rapid changes” in the MIZ should remain cautious and provide a specific and clear definition of both the MIZ itself and also the property of the MIZ that is changing.

Unexpectedly high dimethyl sulfide concentration in high-latitude Arctic sea ice melt ponds

2019 ◽  
Vol 21 (10) ◽  
pp. 1642-1649 ◽  
Author(s):  
Keyhong Park ◽  
Intae Kim ◽  
Jung-Ok Choi ◽  
Youngju Lee ◽  
Jinyoung Jung ◽  
...  
Keyword(s):  
Sea Ice ◽  
High Latitude ◽  
Dimethyl Sulfide ◽  
Arctic Sea Ice ◽  
Sulfide Concentration ◽  
Sea Ice Concentration ◽  
Ice Melt ◽  
Melt Ponds ◽  
Arctic Sea ◽  
Ice Concentration

Dimethyl sulfide (DMS) production in the northern Arctic Ocean has been considered to be minimal because of high sea ice concentration and extremely low productivity.

scholarly journals Sea-Ice Concentration Derived From GNSS Reflection Measurements in Fram Strait

2019 ◽  
Vol 57 (12) ◽  
pp. 10350-10361 ◽  
Author(s):  
A. Maximilian Semmling ◽  
Anja Rosel ◽  
Dmitry V. Divine ◽  
Sebastian Gerland ◽  
Georges Stienne ◽  
...  
Keyword(s):  
Sea Ice ◽  
Fram Strait ◽  
Sea Ice Concentration ◽  
Ice Concentration
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