scholarly journals An Edge-Referenced Surface Fresh Layer in the Beaufort Sea Seasonal Ice Zone

2017 ◽  
Vol 47 (5) ◽  
pp. 1125-1144 ◽  
Author(s):  
Sarah R. Dewey ◽  
James H. Morison ◽  
Jinlun Zhang
Keyword(s):  
Sea Ice ◽  
Large Scale ◽  
Vertical Mixing ◽  
Heat Content ◽  
Beaufort Sea ◽  
Coast Guard ◽  
Ice Melt ◽  
Ice Edge ◽  
Gyre Circulation ◽  
Seasonal Ice Zone

AbstractTo understand the factors causing the interannual variations in the summer retreat of the Beaufort Sea ice edge, Seasonal Ice Zone Reconnaissance Surveys (SIZRS) aboard U.S. Coast Guard Arctic Domain Awareness flights were made monthly from June to October in 2012, 2013, and 2014. The seasonal ice zone (SIZ) is where sea ice melts and reforms annually and encompasses the nominally narrower marginal ice zone (MIZ) where a mix of open-ocean and ice pack processes prevail. Thus, SIZRS provides a regional context for the smaller-scale MIZ processes. Observations with aircraft expendable conductivity–temperature–depth probes reveal a salinity pattern associated with large-scale gyre circulation and the seasonal formation of a shallow (~20 m) fresh layer moving with the ice edge position. Repeat occupations of the SIZRS lines from 72° to 76°N on 140° and 150°W allow a comparison of observed hydrography to atmospheric indices. Using this relationship, the basinwide salinity signals are separated from the fresh layer associated with the ice edge. While this layer extends northward under the ice edge as the melt season progresses, low salinities and warm temperatures appear south of the edge. Within this fresh layer, average salinity is correlated with distance from the ice edge. The salinity observations suggest that the upper-ocean freshening over the summer is dominated by local sea ice melt and vertical mixing. A Price–Weller–Pinkel model analysis reveals that observed changes in heat content and density structure are also consistent with a 1D mixing process.

scholarly journals Arctic sea-ice melt in 2008 and the role of solar heating

2011 ◽  
Vol 52 (57) ◽  
pp. 355-359 ◽  
Author(s):  
Donald K. Perovich ◽  
Jacqueline A. Richter-Menge ◽  
Kathleen F. Jones ◽  
Bonnie Light ◽  
Bruce C. Elder ◽  
...  
Keyword(s):  
Sea Ice ◽  
Heat Input ◽  
Large Scale ◽  
Beaufort Sea ◽  
Arctic Sea Ice ◽  
Solar Heat ◽  
Ice Melt ◽  
Ice Surface ◽  
Arctic Sea ◽  
Ice Concentration

AbstractThere has been a marked decline in the summer extent of Arctic sea ice over the past few decades. Data from autonomous ice mass-balance buoys can enhance our understanding of this decline. These buoys monitor changes in snow deposition and ablation, ice growth, and ice surface and bottom melt. Results from the summer of 2008 showed considerable large-scale spatial variability in the amount of surface and bottom melt. Small amounts of melting were observed north of Greenland, while melting in the southern Beaufort Sea was quite large. Comparison of net solar heat input to the ice and heat required for surface ablation showed only modest correlation. However, there was a strong correlation between solar heat input to the ocean and bottom melting. As the ice concentration in the Beaufort Sea region decreased, there was an increase in solar heat to the ocean and an increase in bottom melting.

scholarly journals Synoptic Conditions, Clouds, and Sea Ice Melt Onset in the Beaufort and Chukchi Seasonal Ice Zone

2017 ◽  
Vol 30 (17) ◽  
pp. 6999-7016 ◽  
Author(s):  
Zheng Liu ◽  
Axel Schweiger
Keyword(s):  
Sea Ice ◽  
Numerical Models ◽  
Precipitable Water ◽  
Reanalysis Data ◽  
Cloud Microphysics ◽  
Low Level ◽  
Ice Melt ◽  
Synoptic Conditions ◽  
High Level ◽  
Seasonal Ice Zone

Cloud response to synoptic conditions over the Beaufort and Chukchi seasonal ice zone is examined. Four synoptic states with distinct thermodynamic and dynamic signatures are identified using ERA-Interim reanalysis data from 2000 to 2014. CloudSat and CALIPSO observations suggest control of clouds by synoptic states. Warm continental air advection is associated with the fewest low-level clouds, while cold air advection generates the most low-level clouds. Low-level clouds are related to lower-tropospheric stability and both are regulated by synoptic conditions. High-level clouds are associated with humidity and vertical motions in the upper atmosphere. Observed cloud vertical and spatial variability is reproduced well in ERA-Interim, but winter low-level cloud fraction is overestimated. This suggests that synoptic conditions constrain the spatial extent of clouds through the atmospheric structure, while the parameterizations for cloud microphysics and boundary layer physics are critical for the life cycle of clouds in numerical models. Sea ice melt onset is related to synoptic conditions. Melt onsets occur more frequently and earlier with warm air advection. Synoptic conditions with the highest temperatures and precipitable water are most favorable for melt onsets even though fewer low-level clouds are associated with these conditions.

scholarly journals Sea ice melt pond fraction estimation from dual-polarisation C-band SAR – Part 2: Scaling in situ to Radarsat-2

2014 ◽  
Vol 8 (1) ◽  
pp. 845-885 ◽  
Author(s):  
R. K. Scharien ◽  
K. Hochheim ◽  
J. Landy ◽  
D. G. Barber
Keyword(s):  
Sea Ice ◽  
Large Scale ◽  
Temporal Frequency ◽  
Model Performance ◽  
Free Water ◽  
Light Transmittance ◽  
The Arctic ◽  
Ice Melt ◽  
Melt Pond

Abstract. Observed changes in the Arctic have motivated efforts to understand and model its components as an integrated and adaptive system at increasingly finer scales. Sea ice melt pond fraction, an important summer sea ice component affecting surface albedo and light transmittance across the ocean-sea ice–atmosphere interface, is inadequately parameterized in models due to a lack of large scale observations. In this paper, results from a multi-scale remote sensing program dedicated to the retrieval of pond fraction from satellite C-band synthetic aperture radar (SAR) are detailed. The study was conducted on first-year sea (FY) ice in the Canadian Arctic Archipelago during the summer melt period in June 2012. Approaches to retrieve the subscale FY ice pond fraction from mixed pixels in RADARSAT-2 imagery, using in situ, surface scattering theory, and image data are assessed. Each algorithm exploits the dominant effect of high dielectric free-water ponds on the VV/HH polarisation ratio (PR) at moderate to high incidence angles (about 40° and above). Algorithms are applied to four images corresponding to discrete stages of the seasonal pond evolutionary cycle, and model performance is assessed using coincident pond fraction measurements from partitioned aerial photos. A RMSE of 0.07, across a pond fraction range of 0.10 to 0.70, is achieved during intermediate and late seasonal stages. Weak model performance is attributed to wet snow (pond formation) and synoptically driven pond freezing events (all stages), though PR has utility for identification of these events when considered in time series context. Results demonstrate the potential of wide-swath, dual-polarisation, SAR for large-scale observations of pond fraction with temporal frequency suitable for process-scale studies and improvements to model parameterizations.

Structure, Salinity and Density of Multi-Year Sea Ice Pressure Ridges

1985 ◽  
Vol 107 (4) ◽  
pp. 493-497 ◽  
Author(s):  
J. A. Richter-Menge ◽  
G. F. N. Cox
Keyword(s):  
Sea Ice ◽  
Large Scale ◽  
Beaufort Sea ◽  
Pressure Ridge ◽  
Sample Data ◽  
Ice Loads ◽  
Scale Properties ◽  
Ice Pressure

Data are presented on the variation of ice structure, salinity, and density in multi-year pressure ridges from the Beaufort Sea. Two continuous multi-year pressure ridge cores are examined as well as ice sample data from numerous other pressure ridges. The results suggest that the large scale properties of multi-year pressure ridges are not isotropic, and that the use of anisotropic ridge models may result in lower design ridge ice loads.

scholarly journals Time and space variability of freshwater content, heat content and seasonal ice melt in the Arctic Ocean from 1991 to 2011

2012 ◽  
Vol 9 (4) ◽  
pp. 2621-2677 ◽  
Author(s):  
M. Korhonen ◽  
B. Rudels ◽  
M. Marnela ◽  
A. Wisotzki ◽  
J. Zhao
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Mixed Layer ◽  
Heat Content ◽  
The Arctic ◽  
Upper Ocean ◽  
Heat Sources ◽  
Time And Space ◽  
Ice Melt ◽  
The Arctic Ocean

Abstract. The Arctic Ocean gains freshwater mainly through river discharge, precipitation and the inflowing low salinity waters from the Pacific Ocean. In addition the recent reduction in sea ice volume is likely to influence the surface salinity and thus contribute to the freshwater content in the upper ocean. The present day freshwater storage in the Arctic Ocean appears to be sufficient to maintain the upper ocean stratification and to protect the sea ice from the deep ocean heat content. The recent freshening has not, despite the established strong stratification, been able to restrain the accelerating ice loss and other possible heat sources besides the Atlantic Water, such as the waters advecting from the Pacific Ocean and the solar insolation warming the Polar Mixed Layer, are investigated. Since the ongoing freshening, oceanic heat sources and the sea ice melt are closely related, this study, based on hydrographic observations, attempts to examine the ongoing variability in time and space in relation to these three properties. The largest time and space variability of freshwater content occurs in the Polar Mixed Layer and the upper halocline. The freshening of the upper ocean during the 2000s is ubiquitous in the Arctic Ocean although the most substantial increase occurs in the Canada Basin where the freshwater is accumulating in the thickening upper halocline. Whereas the salinity of the upper halocline is nearly constant, the freshwater content in the Polar Mixed Layer is increasing due to decreasing salinity. The decrease in salinity is likely to result from the recent changes in ice formation and melting. In contrast, in the Eurasian Basin where the seasonal ice melt has remained rather modest, the freshening of both the Polar Mixed Layer and the upper halocline is mainly of advective origin. While the warming of the Atlantic inflow was widespread in the Arctic Ocean during the 1990s, the warm and saline inflow events in the early 2000s appear to circulate mainly in the Nansen Basin. Nevertheless, even in the Nansen Basin the seasonal ice melt appears independent of the continuously increasing heat content in the Atlantic layer. As no other oceanic heat sources can be identified in the upper layers, it is likely that increased absorption of solar energy has been causing the ice melt prior to the observations.

scholarly journals Oceanographic and meteorological effects on autumn sea-ice distribution in the western Arctic

1991 ◽  
Vol 15 ◽  
pp. 171-177 ◽  
Author(s):  
Robin D. Muench ◽  
Carol H. Pease ◽  
Sigrid A. Salo
Keyword(s):  
Sea Ice ◽  
Chukchi Sea ◽  
Meteorological Data ◽  
Coastal Current ◽  
Ice Melt ◽  
Northern Bering Sea ◽  
Pack Ice ◽  
Edge Location ◽  
Western Arctic ◽  
Ice Edge

Oceanographic, meteorological and sea-ice data were obtained from the northern Bering Sea and Chukchi Sea during the autumns of 1987 and 1988. Ice-edge location was observed from ships and via AVHRR satellite data, and ice-drift information was obtained from ARGOS-tracked drift buoys. Meteorological data were obtained from ships, from an ARGOS-tracked meteorological station and from synoptic charts. The ice edge was significantly farther south in 1988 than during other years and impacted the Alaskan coastline. In 1987, the ice edge was, conversely, anomalously far north. Ice melt-back in certain regions, such as along the Alaskan coast and in Herald Canyon, was due to input from warm ocean currents. The larger-scale interannual differences in ice extent were, however, due to interannual differences in the regional winds. In particular, the anomalous and extreme southward extent of the ice edge during 1988 was due to northerly to northwesterly winds, which held the summer pack ice against the the beach. Meltwater from this ice salt-stratified the upper water column, so that the ice eventually became effectively insulated against vertical flux of heat from the underlying warm water in the coastal current.

scholarly journals Preconditioning of the 2007 sea-ice melt in the eastern Beaufort Sea, Arctic Ocean

2015 ◽  
Vol 56 (69) ◽  
pp. 94-98 ◽  
Author(s):  
Jennifer K. Hutchings ◽  
Donald K. Perovich
Keyword(s):  
Solar Radiation ◽  
Sea Ice ◽  
Arctic Ocean ◽  
Open Water ◽  
Beaufort Sea ◽  
Growth Season ◽  
Water Fraction ◽  
Ice Melt ◽  
Ice Model ◽  
Ice Pack

AbstractDuring summer 2007, perennial sea ice in the Beaufort Sea, Arctic Ocean, experienced an unprecedented amount of basal melt. It has previously been shown that this basal melt was linked to an increase in open-water fraction, increasing absorption of solar radiation into the ocean. GPS ice drifters, deployed around the site where the unprecedented basal melt was observed, provide a coincident observation of local divergence. This divergence is used to drive a multi-thickness category thermodynamic sea-ice model. We demonstrate that ∼ 75% of the observed open-water fraction by midsummer 2007 can be attributed to ice pack divergence during the growth season, preconditioning the ice pack for early melt in summer. Divergence during the melt season explains the remaining 25% of open water. Enhanced ice pack divergence in spring and summer 2007, in response to the increased transport of ice out of the Beaufort Sea, was sufficient to explain the melt observed in summer 2007 and the heat stored in the upper ocean at the end of summer.

Large-Scale Hull Loading of Sea Ice, Lake Ice, and Ice in Tuktoyaktuk Harbour

2001 ◽  
Vol 123 (4) ◽  
pp. 159-169 ◽  
Author(s):  
R. E. Gagnon ◽  
S. J. Jones ◽  
R. Frederking ◽  
P. A. Spencer ◽  
D. M. Masterson
Keyword(s):  
Sea Ice ◽  
Large Scale ◽  
Pollution Prevention ◽  
The Arctic ◽  
Second Phase ◽  
Uniform Pressure ◽  
Lake Ice ◽  
Element Analysis ◽  
Arctic Pollution ◽  
Ice Edge

As part of an INSROP project, large-scale hull loading of first-year sea ice, two series of experiments were carried out to simulate ice loading on a ship’s hull. The first, Phase I, was a preliminary series on freshwater lake ice near Calgary, Alberta, and the second, Phase II, took place in Tuktoyaktuk Harbour in the Canadian Arctic also on essentially freshwater ice. Loading was generated by hydraulic actuators impressing a rigid indentor against an ice edge, and by using flatjacks. A finite element analysis of the test geometry was carried out to assess the deformation and stress distributions in the ice edge for cases with both undamaged and varying degrees of damage. The calculated and measured stiffness of the ice edge agreed for a realistic selection of elastic modulus of the parent ice and damaged ice. The field results did not show conclusively any influence of damage on the failure strength of the ice. A review of these results, and those from Resolute Bay sea ice obtained earlier, showed that the nature of the ice loading, depending on whether it was uniform pressure or uniform deformation, significantly affected the results. The failure stress for uniform pressure tests did not have any dependence on area or aspect ratio. The measured field results gave average ice pressures less than those recommended by the Arctic Pollution Prevention Regulations.

scholarly journals Summertime low clouds mediate the impact of the large-scale circulation on Arctic sea ice

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Yiyi Huang ◽  
Qinghua Ding ◽  
Xiquan Dong ◽  
Baike Xi ◽  
Ian Baxter
Keyword(s):  
Sea Ice ◽  
Large Scale ◽  
Climate Models ◽  
Lower Troposphere ◽  
Arctic Sea Ice ◽  
Albedo Feedback ◽  
Ice Melt ◽  
Low Clouds ◽  
Arctic Sea ◽  
The Impact

AbstractThe rapid Arctic sea ice retreat in the early 21st century is believed to be driven by several dynamic and thermodynamic feedbacks, such as ice-albedo feedback and water vapor feedback. However, the role of clouds in these feedbacks remains unclear since the causality between clouds and these processes is complex. Here, we use NASA CERES satellite products and NCAR CESM model simulations to suggest that summertime low clouds have played an important role in driving sea ice melt by amplifying the adiabatic warming induced by a stronger anticyclonic circulation aloft. The upper-level high pressure regulates low clouds through stronger downward motion and increasing lower troposphere relative humidity. The increased low clouds favor more sea ice melt via emitting stronger longwave radiation. Then decreased surface albedo triggers a positive ice-albedo feedback, which further enhances sea ice melt. Considering the importance of summertime low clouds, accurate simulation of this process is a prerequisite for climate models to produce reliable future projections of Arctic sea ice.

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