scholarly journals Temporal evolution of Arctic sea-ice temperature

2001 ◽  
Vol 33 ◽  
pp. 207-211 ◽  
Author(s):  
Donald K. Perovich ◽  
Bruce C. Elder
Keyword(s):  
Spatial Variability ◽  
Cold Front ◽  
Freezing Point ◽  
Heat Budget ◽  
General Pattern ◽  
Pond Water ◽  
Early Spring ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Environmental Forcing

AbstractVertical profiles of temperature from the air through the snow and ice and into the upper ocean were measured over an annual cycle, from October 1997 to October 1998, as part of a study of the Surface Heat Budget of the Arctic Ocean (SHEBA). These observations were made at nine locations, including young ice, ponded ice, undeformed ice, a hummock, a consolidated ridge and a new blocky ridge. All of the sites had similar environmental forcing, with air temperatures at the different sites typically within 1°C. In general, the seasonal evolution of ice temperature followed a pattern of (1) a cold front propagating down through the ice in the fall, (2) cold ice temperatures and ice growth in late fall, winter and early spring, and (3) warming to the freezing point in the summer. Within this general pattern, there was considerable spatial variability in the temperature profiles, particularly during winter. For example, snow/ice interface temperatures varied by as much as 30°C between sites. The coldest ice temperatures were observed in a consolidated ridge with a thin snow cover, while the warmest were in ponded ice. The warm pond temperatures were a result of two factors: the initial cooling in the fall was retarded by freezing of pond water, and the depressed surface of the pond was quickly covered by a deep layer of snow (0.6 m). In an 8 m thick unconsolidated ridge, the cold front did not penetrate to the ice bottom during winter, and a portion of the interior remained below freezing during the summer. The spatial variability in snow depth and ice conditions can result in situations where there is significant horizontal transport of heat.

scholarly journals Seasonal changes in Arctic sea-ice morphology

2001 ◽  
Vol 33 ◽  
pp. 171-176 ◽  
Author(s):  
Donald K. Perovich ◽  
Jacqueline A. Richter-Menge ◽  
Walter B. Tucker
Keyword(s):  
Sea Ice ◽  
Heat Budget ◽  
Open Water ◽  
Ice Cover ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Ice Surface ◽  
Arctic Sea ◽  
Dynamic Forcing ◽  
Break Up

AbstractThe morphology of the Arctic sea-ice cover undergoes large changes over an annual cycle. These changes have a significant impact on the heat budget of the ice cover, primarily by affecting the distribution of the solar radiation absorbed in the ice-ocean system. In spring, the ice is snow-covered and ridges are the prominent features. The pack consists of large angular floes, with a small amount of open water contained primarily in linear leads. By the end of summer the ice cover has undergone a major transformation. The snow cover is gone, many of the ridges have been reduced to hummocks and the ice surface is mottled with melt ponds. One surface characteristic that changes little during the summer is the appearance of the bare ice, which remains white despite significant melting. The large floes have broken into a mosaic of smaller, rounded floes surrounded by a lace of open water. Interestingly, this break-up occurs during summer when the dynamic forcing and the internal ice stress are small During the Surface Heat Budget of the Arctic Ocean (SHEBA) field experiment we had an opportunity to observe the break-up process both on a small scale from the ice surface, and on a larger scale via aerial photographs. Floe break-up resulted in large part from thermal deterioration of the ice. The large floes of spring are riddled with cracks and leads that formed and froze during fall, winter and spring. These features melt open during summer, weakening the ice so that modest dynamic forcing can break apart the large floes into many fragments. Associated with this break-up is an increase in the number of floes, a decrease in the size of floes, an increase in floe perimeter and an increase in the area of open water.

scholarly journals Arctic sea-ice area and volume production:1996/97 versus 1997/98

2002 ◽  
Vol 34 ◽  
pp. 447-453 ◽  
Author(s):  
Ron Kwok
Keyword(s):  
Arctic Ocean ◽  
Large Scale ◽  
Heat Budget ◽  
Ice Cover ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Ice Thickness ◽  
The Arctic Ocean ◽  
Volume Production ◽  
Area And Volume

AbstractThe RADARSAT geophysical processor system (RGPS) produces measurements of ice motion and estimates of ice thickness using repeat synthetic aperture radar maps of the Arctic Ocean. From the RGPS products, we compute the net deformation and advection of the winter ice cover using the motion observations, and the seasonal ice area and volume production using the estimates of ice thickness. The results from the winters of 1996/97 and 1997/98 are compared. The second winter is of particular interest because it coincides with the Surface Heat Budget of the Arctic Ocean (SHEBA) field program. The character of the deformation of the ice cover from the two years is very different. Over a domain covering a large part of the western Arctic Ocean (~2.5 × 106 km2), the net divergence of that area during the 6 months of the first winter was 2.7% and for the second winter was 49.3%. In a subregion where the SHEBA camp was located, the net divergence was almost 38% compared to a net divergence of the same subregion of ~9% in 1996/97. The resulting deformation created a much larger volume of seasonal ice than in the earlier year. The net seasonal ice-volume production is 1.6 times (0.38 m vs 0.62 m) that of the first year. In addition to the larger divergence, this part of the ice cover advected a longer distance toward the Chukchi Sea over the same time-span. The total coverage of multi-year ice remained almost identical at ~2.08 × 106 km2, or 83% of the initial area of the domain. In this paper, we compare the behavior of the ice cover over the two winters and discuss these observations in the context of large-scale ice motion and atmospheric-pressure pattern.

Turbulent structure in the upper ocean during the MOSAiC drift

2021 ◽  
Author(s):  
Ilker Fer ◽  
Till Baumann ◽  
Ying-Chih Fang ◽  
Mario Hoppmann ◽  
Zoe Koenig ◽  
...  
Keyword(s):  
Sea Ice ◽  
Dissipation Rate ◽  
Fast Response ◽  
Arctic Sea Ice ◽  
Turbulent Structure ◽  
The Arctic ◽  
Time Variability ◽  
High Time Resolution ◽  
Storm Events ◽  
Environmental Forcing

<p>Ocean turbulence measurements under the Arctic sea ice cover are sparse, especially in winter conditions. During the drift of the MOSAiC main camp, we collected vertical profiles of ocean microstructure in the upper 50-80 m using an ascending vertical microstructure profiler. Each profile terminated when the profiler hit the sea ice or broke through the surface in leads, which resolved the turbulent structure up to the ice or surface. These sporadic profile measurements were supplemented by an ice-moored system equipped with fast-response thermistors, collecting continuous time series at approximately 50 m below the ice. Both instruments are manufactured by Rockland Scientific, Canada. While the profiling was conducted from mid-February to mid-September 2020, the moored measurements were in the period between mid-December 2019 and late April 2020, spatially covering from 88°N30' to 84°N in the Amundsen Basin. From the vertical profiler, dissipation rate of turbulent kinetic energy, ε was estimated using the shear probes and the relatively standard methods applied to shear spectra. From the moored records, ε and dissipation rate of temperature variance, χ, were estimated using the high-resolution temperature records and maximum likelihood spectra fitting to the Batchelor spectrum using 75 s segments. This gives an exceptionally high time resolution of turbulence estimates, albeit from a fixed depth. Estimates ranged between 10<sup>-11</sup> to 10<sup>-6</sup> W/kg for ε , and 10<sup>-12</sup> to 10<sup>-6</sup> C<sup>2</sup>/s for χ. The vertical distribution of ε in the upper 50 m and the time variability and statistics of moored estimates will be discussed in relation to various environmental forcing conditions including storm events and convection.</p>

scholarly journals Indirect measurements of the mass balance of summer Arctic sea ice with an electromagnetic induction technique

2001 ◽  
Vol 33 ◽  
pp. 194-200 ◽  
Author(s):  
H. Eicken ◽  
W. B. Tucker ◽  
D. K. Perovich
Keyword(s):  
Mass Balance ◽  
Electromagnetic Induction ◽  
Heat Budget ◽  
Chukchi Sea ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Ice Thickness ◽  
Apparent Conductivity ◽  
Melt Ponds ◽  
Sampling Statistics

AbstractIn the framework of the Surface Heat Budget of the Arctic (SHEBA) study, indirect, non-invasive ice mass-balance measurements were carried out at a drifting station in the northern Chukchi Sea between May and August 1998. Ice thickness was derived from electromagnetic induction (EM) measurements of apparent conductivity along 13 profiles (60−900 m long). As shown through sensitivity studies with a one-dimensional model, the apparent conductivity data from individual points can be inverted to yield estimates of ice thickness and ablation with an accuracy of approximately 0.05 m (for 2 m thick level ice). Ablation rates were 8−18 mm d−1, with total ablation amounting to roughly 0.9−1.2 m. Measurements of thickness and melt rates along different profiles in undeformed multi-year ice corresponded closely, indicating that the sampling statistics are adequate. The roughness of undeformed ice has been found to increase during the summer due to deepening of melt ponds and enhanced bottom melt. Ice under melt ponds was disproportionately thinner, most likely a result of thicker snow cover reducing winter accretion.

scholarly journals The interaction of ultraviolet light with Arctic sea ice during SHEBA

2006 ◽  
Vol 44 ◽  
pp. 47-52 ◽  
Author(s):  
Donald K. Perovich
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Ultraviolet Light ◽  
Heat Budget ◽  
Ice Cover ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Transfer Model ◽  
The Arctic Ocean ◽  
Ultraviolet Irradiance

AbstractThe reflection, absorption and transmission of ultraviolet light by a sea-ice cover strongly impacts primary productivity, higher trophic components of the food web, and humans. Measurements of the incident irradiance at 305, 320, 340 and 380 nm and of the photosynthetically active radiation were made from April through September 1998 as part of the SHEBA (Surface Heat Budget of the Arctic Ocean program) field experiment in the Arctic Ocean. In addition, observations of snow depth and ice thickness were made at more than 100 sites encompassing a comprehensive range of conditions. The thickness observations were combined with a radiative transfer model to compute a time series of the ultraviolet light transmitted by the ice cover from April through September. Peak values of incident ultraviolet irradiance occurred in mid-June. Peak transmittance was later in the summer at the end of the melt season when the snow cover had completely melted, the ice had thinned and pond coverage was extensive. The fraction of the incident ultraviolet irradiance transmitted through the ice increased by several orders of magnitude as the melt season progressed. Ultraviolet transmittance was approximately a factor of ten greater for melt ponds than bare ice. Climate change has the potential to alter the amplitude and timing of the annual albedo cycle of sea ice. If the onset of melt occurs at increasingly earlier dates, ultraviolet transmittance will be significantly enhanced, with potentially deleterious biological impacts.

From red to white: the time-varying nature of ocean heat flux to Arctic sea ice

2020 ◽  
Author(s):  
Srikanth Toppaladoddi ◽  
Andrew Wells
Keyword(s):  
Heat Flux ◽  
Sea Ice ◽  
Time Series Data ◽  
Heat Budget ◽  
Temporal Variations ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Series Data ◽  
Fluctuation Analysis ◽  
Arctic Sea

<p>Arctic sea ice is one of the most sensitive components of the Earth’s climate system. The underlying ocean plays an important role in the evolution of the ice cover through its heat flux at the ice-ocean interface which moderates ice growth and melt. Despite its importance, the spatio-temporal variations of this heat flux are not well understood. In this work, we combine direct numerical simulations of turbulent convection over fractal surfaces and analysis of time-series data from the Surface Heat Budget of the Arctic Ocean (SHEBA) program using Multifractal Detrended Fluctuation Analysis (MFDFA) to understand the nature of fluctuations in this heat flux. We identify key physical processes associated with the observed Hurst exponents calculated by the MFDFA, and how these evolve over time. We also discuss ongoing work on constructing simple stochastic models of the ocean heat flux to the ice, and potential use as a parameterisation.</p>

scholarly journals Seasonal variability of ice temperature upon the results of measuring at “North Pole-38” drifting station

2017 ◽  
pp. 66-75 ◽  
Author(s):  
V. V. Kharitonov
Keyword(s):  
Heat Flux ◽  
Cold Front ◽  
Freezing Point ◽  
General Pattern ◽  
Time Profile ◽  
North Pole ◽  
First Year ◽  
Temperature Profiles ◽  
Vertical Profiles ◽  
Second Year

Vertical profiles of ice temperature were measured in November 2010 – September 2011 at “North Pole-38” drifting station. These observations were made at five locations, including young ice, residual first-year ice, second-year ice, multi-year ice. Methods of measurements are considered. Time-temperature profiles for all types of ice as well as time profile for the gradient of temperature of ice, as an example, are shown. A snow cover gives substantial thermal resistance, reducing a heat flux between atmosphere and ocean. The periods of warming-up and cooling of ice in the annual cycle alternate with periods, when vertical distribution of ice temperature close to linear: with a maximal gradient in winter and zero gradient in summer. A general pattern of the seasonal evolution of ice temperature is discussed. A cold front is propagating down through the ice from October to June. Ice growth lasts, on the average, to a middle of May. Warming of ice to the freezing point occurs mainly in August.

scholarly journals Increasing riverine heat influx triggers Arctic sea ice decline and oceanic and atmospheric warming

2020 ◽  
Vol 6 (45) ◽  
pp. eabc4699 ◽  
Author(s):  
Hotaek Park ◽  
Eiji Watanabe ◽  
Youngwook Kim ◽  
Igor Polyakov ◽  
Kazuhiro Oshima ◽  
...  
Keyword(s):  
Sea Ice ◽  
Land Surface ◽  
Heat Budget ◽  
Ocean Model ◽  
Early Summer ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Surface Model ◽  
Arctic Sea ◽  
Atmospheric Warming

Arctic river discharge increased over the last several decades, conveying heat and freshwater into the Arctic Ocean and likely affecting regional sea ice and the ocean heat budget. However, until now, there have been only limited assessments of riverine heat impacts. Here, we adopted a synthesis of a pan-Arctic sea ice–ocean model and a land surface model to quantify impacts of river heat on the Arctic sea ice and ocean heat budget. We show that river heat contributed up to 10% of the regional sea ice reduction over the Arctic shelves from 1980 to 2015. Particularly notable, this effect occurs as earlier sea ice breakup in late spring and early summer. The increasing ice-free area in the shelf seas results in a warmer ocean in summer, enhancing ocean–atmosphere energy exchange and atmospheric warming. Our findings suggest that a positive river heat–sea ice feedback nearly doubles the river heat effect.

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