Variability in categories of <scp>A</scp>rctic sea ice in <scp>F</scp>ram <scp>S</scp>trait

Hansen, Edmond; Ekeberg, Ole-Christian; Gerland, Sebastian; Pavlova, Olga; Spreen, Gunnar; Tschudi, M. A.

doi:10.1002/2014jc010048

Cited by 23 publications

(22 citation statements)

References 28 publications

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“…The increase is related to an increase in the fraction of deformed ice between 2010 and 2012. This is in agreement with Hansen et al (2014) who estimate that the contribution of thick, deformed ice towards the mean ice thickness is decreasing from about 70 % in 2001 to about 50 % in 2011. The comparison of AEM-and GEM-based observations may introduce an additional uncertainty and must be limited to a comparable range of the thickness distribution.…”

Section: Fram Strait Sea Ice Thickness Source Area and Agesupporting

confidence: 93%

“…Similar to the modal ice thickness, some of the interannual variability may be related to a varying age composition, but the overall decline is independent of ice age. Hence, the reduction of the deformed ice fraction points to a reduction in the deformation history in source areas and along pathways, mainly in the Laptev Sea and along the Transpolar Drift, which is in agreement with findings of Hansen et al (2013Hansen et al ( , 2014. Following the authors, the decrease can be associated with changes in wind stress or a loss in perennial ice (decrease in ice age), since younger ice likely contains less consolidated pressure ridges.…”

Section: Fram Strait Sea Ice Thickness Source Area and Agesupporting

confidence: 87%

“…In this study we apply the uncertainty estimates provided by Sumata et al (2015) for different drift speeds and ice concentration to evaluate reliability of our flux calculations. As an additional quality control we compare our results with area flux estimates from Kloster and Sandven (2011) and Smedsrud et al (2011) (Fig. 7, red and gray line).…”

Section: Summer Sea Ice Area and Volume Fluxesmentioning

confidence: 99%

“…7, red and gray line). Area flux calculations of Kloster and Sandven (2011) Kloster and Sandven (2011) to estimate the linear regression between geostrophic winds, sea ice drift speed and ice area export. The linear relationship was then used to reconstruct ice area export based on pressure differences for the period between 1957 and 2010.…”

Section: Summer Sea Ice Area and Volume Fluxesmentioning

confidence: 99%

“…The linear relationship was then used to reconstruct ice area export based on pressure differences for the period between 1957 and 2010. A direct comparison of our area flux estimates with the findings of Smedsrud et al (2011) and Kloster and Sandven (2011) is difficult, because area flux estimates are based on different methods and were made at different latitude gates. However, a comparison of our findings with area export estimates of others reveals that the trend in NSIDC export rates is much higher (37.6 % decade −1 for the period 1980-2012) than the trend found by Kloster and Sandven (2011) , and in contrast to Kwok (2009) and Kwok et al (2013), who did not observe any significant trend in ice area export for the past decades.…”

Section: Summer Sea Ice Area and Volume Fluxesmentioning

confidence: 99%

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Recent summer sea ice thickness surveys in Fram Strait and associated ice volume fluxes

et al. 2016

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Abstract. Fram Strait is the main gateway for sea ice export out of the Arctic Ocean, and therefore observations there give insight into the composition and properties of Arctic sea ice in general and how it varies over time. A data set of ground-based and airborne electromagnetic ice thickness measurements collected during summer between 2001 and 2012 is presented here, including long transects well into the southern part of the Transpolar Drift obtained using fixedwing aircrafts. The primary source of the surveyed sea ice leaving Fram Strait is the Laptev Sea and its age has decreased from 3 to 2 years between 1990 and 2012. The thickness data consistently also show a general thinning of sea ice for the last decade, with a decrease in modal thickness of second year and multiyear ice, and a decrease in mean thickness and fraction of ice thicker than 3 m. Local melting in the strait was investigated in two surveys performed in the downstream direction, showing a decrease in sea ice thickness of 0.19 m degree −1 latitude south of 81 • N. Further north variability in ice thickness is more related to differences in age and deformation. The thickness observations were combined with ice area export estimates to calculate summer volume fluxes of sea ice. While satellite data show that monthly ice area export had positive trends since 1980 (10.9 × 10 3 km 2 decade −1 ), the summer (July and August) ice area export is low with high uncertainties. The average volume export amounts to 16.78 km 3 . Naturally, the volume flux estimates are limited to the period when airborne thickness surveys are available. Nevertheless, we could show that the combination of satellite data and airborne observations can be used to determine volume fluxes through Fram Strait and as such, can be used to bridge the lack of satellite-based sea ice thickness information in summer.

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Section: Fram Strait Sea Ice Thickness Source Area and Agesupporting

confidence: 93%

Section: Fram Strait Sea Ice Thickness Source Area and Agesupporting

confidence: 87%

Section: Summer Sea Ice Area and Volume Fluxesmentioning

confidence: 99%

Section: Summer Sea Ice Area and Volume Fluxesmentioning

confidence: 99%

Section: Summer Sea Ice Area and Volume Fluxesmentioning

confidence: 99%

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Recent summer sea ice thickness surveys in Fram Strait and associated ice volume fluxes

et al. 2016

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Time variability in the annual cycle of sea ice thickness in the Transpolar Drift

et al. 2015

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The annual cycle of modal and mean sea ice thickness was derived from upward looking sonar ice thickness observations (1990–2011) in Fram Strait. The average annual peak‐to‐trough amplitude of the mode of 0.54 m is superimposed on interannual variability with peak‐to‐trough amplitudes of 0.73 m on time scales of 6–8 years, which again is superimposed on a long‐term trend of −0.55 m/decade over the observation period. The long‐term trend is stronger for April than for August, the average months of maximum and minimum modal thickness. As a result, the annual peak‐to‐trough modal thickness amplitude was reduced by 30% between the 1990s and the 2000s. The average annual peak‐to‐trough amplitude of the mean ice thickness of 1.20 m is also superimposed on interannual variability, with as much as 0.97 m thickness change over only 3 years. These two modes of variability are superimposed on a long‐term trend of −0.35 m/decade through the entire data set. In contrast to the modal thickness, the long‐term trend is weaker for the average month of maximum mean thickness (June), than for the average month of minimum (September). Therefore, the annual peak‐to‐trough amplitude of the mean ice thickness increased by 14% between the 1990s and the 2000s.

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Thin Sea Ice, Thick Snow, and Widespread Negative Freeboard Observed During N‐ICE2015 North of Svalbard

et al. 2018

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In recent years, sea‐ice conditions in the Arctic Ocean changed substantially toward a younger and thinner sea‐ice cover. To capture the scope of these changes and identify the differences between individual regions, in situ observations from expeditions are a valuable data source. We present a continuous time series of in situ measurements from the N‐ICE2015 expedition from January to June 2015 in the Arctic Basin north of Svalbard, comprising snow buoy and ice mass balance buoy data and local and regional data gained from electromagnetic induction (EM) surveys and snow probe measurements from four distinct drifts. The observed mean snow depth of 0.53 m for April to early June is 73% above the average value of 0.30 m from historical and recent observations in this region, covering the years 1955–2017. The modal total ice and snow thicknesses, of 1.6 and 1.7 m measured with ground‐based EM and airborne EM measurements in April, May, and June 2015, respectively, lie below the values ranging from 1.8 to 2.7 m, reported in historical observations from the same region and time of year. The thick snow cover slows thermodynamic growth of the underlying sea ice. In combination with a thin sea‐ice cover this leads to an imbalance between snow and ice thickness, which causes widespread negative freeboard with subsequent flooding and a potential for snow‐ice formation. With certainty, 29% of randomly located drill holes on level ice had negative freeboard.

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Variability in categories of Arctic sea ice in Fram Strait

Cited by 23 publications

References 28 publications

Recent summer sea ice thickness surveys in Fram Strait and associated ice volume fluxes

Recent summer sea ice thickness surveys in Fram Strait and associated ice volume fluxes

Time variability in the annual cycle of sea ice thickness in the Transpolar Drift

Thin Sea Ice, Thick Snow, and Widespread Negative Freeboard Observed During N‐ICE2015 North of Svalbard

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