Seasonal   and   interannual   variability   of   sea-ice   state variables:  Observations  and  predictions  for  landfast  ice  in northern Alaska and Svalbard

Oggier, Marc; Eicken, Hajo; Jin, Meibing; Høyland, Knut V.

doi:10.5194/tc-2020-52

Cited by 3 publications

(5 citation statements)

References 35 publications

(72 reference statements)

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“…For an order-of-magnitude estimate of permeability contrasts, we consider granular ice to be confined to the top ice layers and columnar ice to constitute the bulk of the underlying ice cover. For typical salinity profiles at the end of the growth season (Oggier and others, 2020 a ), salinities of granular and columnar ice are at roughly 10 and 5‰, respectively. With a surface temperature of −10°C, the brine volume fraction is about 5% for both ice textures.…”

Section: Discussionmentioning

confidence: 95%

“…1). The ice is representative of Arctic undeformed sea ice, both in terms of microstructure and ice properties (Druckenmiller and others, 2009; Oggier and others, 2020 a ). We collected microstructure samples at three different times throughout the seasonal cycle to be representative of the growth period (end of March), the transition to the melt season (mid-May), and the melt period (mid-June).…”

Section: Methodsmentioning

confidence: 99%

“…Winter 2014 was warmer than 2013 by about 2°C on average (Eicken, 2016). At the same time, we measured temperature and salinity profiles on co-located ice cores, using standard methods (Oggier and others, 2020 a ). Brine volume fraction was later computed from salinity and temperature profiles (Cox and Weeks, 1983).…”

Section: Methodsmentioning

confidence: 99%

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Seasonal evolution of granular and columnar sea ice pore microstructure and pore network connectivity

Oggier

Eicken

2022

J. Glaciol.

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Sea-ice pore microstructure constrains ice transport properties, affecting fluid flow relevant to oil-in-ice transport and biogeochemical processes. Motivated by a lack of pore microstructural data, in particular for granular ice and across the seasonal cycle, throat size, tortuosity, connectivity, and other microstructural variables were derived from X-ray computed tomography for brine-filled pores in seasonal landfast ice off northern Alaska. Data were obtained for granular and columnar ice during the ice growth, transition, and melt season. While granular ice exhibits a more heterogeneous pore space than columnar ice, pore and throat size distributions are comparable. The greater tortuosity of pores in granular (1.2 < τg < 1.7) compared to columnar ice (1.0 < τc < 1.1) compounded with a less interconnected pore space translates into lower permeability for granular ice during the growth season for a given porosity. The microstructural data explain findings of granular ice hindering vertical oil-in-ice transport during ice growth and transition stage. With granular ice more frequent in the changing Arctic, data from studies such as this are needed to inform improved modeling of porosity-permeability relationships.

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Section: Discussionmentioning

confidence: 95%

Section: Methodsmentioning

confidence: 99%

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Seasonal evolution of granular and columnar sea ice pore microstructure and pore network connectivity

Oggier

Eicken

2022

J. Glaciol.

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“…This work was performed at 2 main coring sites (Figure S2 with Tables S2 and S3), one on FYI and the other on SYI, which was the oldest ice at the start of MOSAiC. We used the approach recommended by Oggier et al (2020) to section the ice cores, relative to both the ice surface and ice bottom (Section 4.2), to better capture the processes at the surface and bottom interfaces. The physical properties affect energy and matter fluxes and ecosystem processes in sea ice and are also important to the RS of sea ice (Section 2.13).…”

Section: Ice Coringmentioning

confidence: 99%

Overview of the MOSAiC expedition: Snow and sea ice

et al. 2022

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Year-round observations of the physical snow and ice properties and processes that govern the ice pack evolution and its interaction with the atmosphere and the ocean were conducted during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition of the research vessel Polarstern in the Arctic Ocean from October 2019 to September 2020. This work was embedded into the interdisciplinary design of the 5 MOSAiC teams, studying the atmosphere, the sea ice, the ocean, the ecosystem, and biogeochemical processes. The overall aim of the snow and sea ice observations during MOSAiC was to characterize the physical properties of the snow and ice cover comprehensively in the central Arctic over an entire annual cycle. This objective was achieved by detailed observations of physical properties and of energy and mass balance of snow and ice. By studying snow and sea ice dynamics over nested spatial scales from centimeters to tens of kilometers, the variability across scales can be considered. On-ice observations of in situ and remote sensing properties of the different surface types over all seasons will help to improve numerical process and climate models and to establish and validate novel satellite remote sensing methods; the linkages to accompanying airborne measurements, satellite observations, and results of numerical models are discussed. We found large spatial variabilities of snow metamorphism and thermal regimes impacting sea ice growth. We conclude that the highly variable snow cover needs to be considered in more detail (in observations, remote sensing, and models) to better understand snow-related feedback processes. The ice pack revealed rapid transformations and motions along the drift in all seasons. The number of coupled ice–ocean interface processes observed in detail are expected to guide upcoming research with respect to the changing Arctic sea ice.

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“…Pioneering work provided a landfast FYI time series in the Canadian Arctic from freeze-up to melt onset (Nakawo and Sinha, 1981), while Cox and Weeks (1988) compared numerical modelling results of FYI growth and field data to understand the evolution of sea ice properties. Time series of FYI in the growth and melt seasons have also been performed in Alaskan and Svalbard landfast ice (Oggier et al, 2020). Work by Granskog et al (2017) compared FYI and SYI salinity and oxygen isotopic composition in drifting ice north of Svalbard but their data are limited to short time series on single floes over the January to June period.…”

Section: Introductionmentioning

confidence: 99%

Deciphering the Properties of Different Arctic Ice Types During the Growth Phase of MOSAiC: Implications for Future Studies on Gas Pathways

et al. 2022

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The increased fraction of first year ice (FYI) at the expense of old ice (second-year ice (SYI) and multi-year ice (MYI)) likely affects the permeability of the Arctic ice cover. This in turn influences the pathways of gases circulating therein and the exchange at interfaces with the atmosphere and ocean. We present sea ice temperature and salinity time series from different ice types relevant to temporal development of sea ice permeability and brine drainage efficiency from freeze-up in October to the onset of spring warming in May. Our study is based on a dataset collected during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) Expedition in 2019 and 2020. These physical properties were used to derive sea ice permeability and Rayleigh numbers. The main sites included FYI and SYI. The latter was composed of an upper layer of residual ice that had desalinated but survived the previous summer melt and became SYI. Below this ice a layer of new first-year ice formed. As the layer of new first-year ice has no direct contact with the atmosphere, we call it insulated first-year ice (IFYI). The residual/SYI-layer also contained refrozen melt ponds in some areas. During the freezing season, the residual/SYI-layer was consistently impermeable, acting as barrier for gas exchange between the atmosphere and ocean. While both FYI and SYI temperatures responded similarly to atmospheric warming events, SYI was more resilient to brine volume fraction changes because of its low salinity (< 2). Furthermore, later bottom ice growth during spring warming was observed for SYI in comparison to FYI. The projected increase in the fraction of more permeable FYI in autumn and spring in the coming decades may favor gas exchange at the atmosphere-ice interface when sea ice acts as a source relative to the atmosphere. While the areal extent of old ice is decreasing, so is its thickness at the onset of freeze-up. Our study sets the foundation for studies on gas dynamics within the ice column and the gas exchange at both ice interfaces, i.e. with the atmosphere and the ocean.

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Seasonal and interannual variability of sea-ice state variables: Observations and predictions for landfast ice in northern Alaska and Svalbard

Cited by 3 publications

References 35 publications

Seasonal evolution of granular and columnar sea ice pore microstructure and pore network connectivity

Seasonal evolution of granular and columnar sea ice pore microstructure and pore network connectivity

Overview of the MOSAiC expedition: Snow and sea ice

Deciphering the Properties of Different Arctic Ice Types During the Growth Phase of MOSAiC: Implications for Future Studies on Gas Pathways

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