Characterization of springtime leads in the Beaufort/Chukchi Seas from airborne and satellite observations during FIRE/SHEBA

Tschudi, M. A.; Maslanik, James A

doi:10.1029/2000jc000541

Cited by 28 publications

(28 citation statements)

References 33 publications

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“…Brine rejection and salinization of the water column can continue even when new ice has been formed in the lead (Smith et al, ). In the Chukchi Sea, leads tend to be 100 m or less in width, several kilometers in length, and oriented perpendicular to the prevailing wind; although the currents can play a role as well (Tschudi et al, ). The leads during this study were generally 50–200 m long (Lowry et al, ).…”

Section: Resultsmentioning

confidence: 99%

Characteristics and Transformation of Pacific Winter Water on the Chukchi Sea Shelf in Late Spring

et al. 2019

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Data from a late spring survey of the northeast Chukchi Sea are used to investigate various aspects of newly ventilated winter water (NVWW). More than 96% of the water sampled on the shelf was NVWW, the saltiest (densest) of which tended to be in the main flow pathways on the shelf. Nearly all of the hydrographic profiles on the shelf displayed a two‐layer structure, with a surface mixed layer and bottom boundary layer separated by a weak density interface (on the order of 0.02 kg/m3). Using a polynya model to drive a one‐dimensional mixing model, it was demonstrated that, on average, the profiles would become completely homogenized within 14–25 hr when subjected to the March and April heat fluxes. A subset of the profiles would become homogenized when subjected to the May heat fluxes. Since the study domain contained numerous leads within the pack ice—many of them refreezing—and since some of the measured profiles were vertically uniform in density, this suggests that NVWW is formed throughout the Chukchi shelf via convection within small openings in the ice. This is consistent with the result that the salinity signals of the NVWW along the central shelf pathway cannot be explained solely by advection from Bering Strait or via modification within large polynyas. The local convection would be expected to stir nutrients into the water column from the sediments, which explains the high nitrate concentrations observed throughout the shelf. This provides a favorable initial condition for phytoplankton growth on the Chukchi shelf.

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Section: Resultsmentioning

confidence: 99%

Characteristics and Transformation of Pacific Winter Water on the Chukchi Sea Shelf in Late Spring

et al. 2019

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“…The albedo of the ice cover is strongly influenced by the pond fraction [ Fetterer and Untersteiner , 1998; Perovich et al , 2002a]. Because of this importance, pond fractions were determined by analyzing aerial photographs [ Tschudi et al , 1997, 2002; Perovich et al , 2002b]. As part of the mass balance program, we measured pond extent and depth along the 200‐m‐long albedo survey line every four days from mid‐June through mid‐August [ Perovich et al , 2002a].…”

Section: Resultsmentioning

confidence: 99%

Thin and thinner: Sea ice mass balance measurements during SHEBA

et al. 2003

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[1] As part of a large interdisciplinary study of the Surface Heat Budget of the Arctic Ocean (SHEBA), we installed more than 135 ice thickness gauges to determine the sea ice mass balance. While installing these gauges during the fall of 1997, we found that much of the multiyear ice cover was only 1 m thick, considerably thinner than expected. Over the course of the yearlong field experiment we monitored the mass balance for a wide variety of ice types, including first-year ice, ponded ice, unponded ice, multiyear ice, hummocks, new ridges, and old ridges. Initial ice thicknesses for these sites ranged from 0.3 to 8 m, and snow depths varied from a few centimeters to more than a meter. However, for all of their differences and variety, these thickness gauges sites shared a common trait: at every site, there was a net thinning of the ice during the SHEBA year. The thin ice found in October 1997 was even thinner in October 1998. The annual cycle of ice thickness was also similar at all sites. There was a steady increase in thickness through the winter that gradually tapered off in the spring. This was followed by a steep drop off in thickness during summer melt and another tapering in late summer and early fall as freeze-up began. Maximum surface melting was in July, while bottom ablation peaked in August. Combining results from the sites, we found an average winter growth of 0.51 m and a summer melt of 1.26 m, which consisted of 0.64 m of surface melt and 0.62 m of bottom melt. There was a weak trend for thicker ice to have less winter growth and greater net loss for the year; however, ice growth was also impacted by the snow depth. Considerable variability was observed between sites in both accretion and ablation. The total accretion during the 9-month growth season ranged from zero for thick ridged ice to more than a meter for young ice. Ponds tended to have a large amount of surface melting, while ridges had considerable bottom ablation.

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“…An uncertainty of 10% of the measured fraction has been assumed. In a second campaign in July, a video camera was used to measure the open water fraction on five days [ Tschudi et al , 2002]. The open water fraction was 0.05 to 0.09 at this time.…”

Section: Data Assimilationmentioning

confidence: 99%

Changes in the modeled ice thickness distribution near the Surface Heat Budget of the Arctic Ocean (SHEBA) drifting ice camp

Lindsay

2003

J. Geophys. Res.

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[1] In the polar oceans the ice thickness distribution controls the exchange of heat between the ocean and the atmosphere and determines the strength of the ice. The Surface Heat Budget of the Arctic Ocean (SHEBA) experiment included a year-long field program centered on a drifting ice station in the Beaufort and Chukchi Seas in the Arctic Ocean from October 1997 through October 1998. Here we use camp observations and develop methods to assimilate ice thickness and open water observations into a model in order to estimate the evolution of the thickness distribution in the vicinity of the camp. A thermodynamic model is used to simulate the ice growth and melt, and an ice redistribution model is used to simulate the opening and ridging processes. Data assimilation procedures are developed and then used to assimilate observations of the thickness distribution. Assimilated observations include those of the thin end of the distribution determined by aircraft surveys of the surface temperature and helicopter photographic surveys and aircraft microwave estimates of the open water fraction. The deformation of the ice was determined primarily from buoy and RADARSAT Geophysical Processor System (RGPS) measurements of the ice velocity. Because of the substantial convergence and ridging observed in the spring and summer, the estimated mean ice thickness increases by 59%, from 1.53 to 2.44 m, over the year in spite of a net thermodynamic ice loss for most multiyear ice.

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Characterization of springtime leads in the Beaufort/Chukchi Seas from airborne and satellite observations during FIRE/SHEBA

Cited by 28 publications

References 33 publications

Characteristics and Transformation of Pacific Winter Water on the Chukchi Sea Shelf in Late Spring

Characteristics and Transformation of Pacific Winter Water on the Chukchi Sea Shelf in Late Spring

Thin and thinner: Sea ice mass balance measurements during SHEBA

Changes in the modeled ice thickness distribution near the Surface Heat Budget of the Arctic Ocean (SHEBA) drifting ice camp

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