How fast is landfast sea ice? A study of the attachment and detachment of nearshore ice at Barrow, Alaska

Mahoney, Andrew R.; Eicken, Hajo; Shapiro, L. H.

doi:10.1016/j.coldregions.2006.09.005

Cited by 81 publications

(99 citation statements)

References 23 publications

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“…Mahoney et al (2007a) found that the breakup of fast ice off the coast of northern Alaska was correlated with the onset of thawing air temperatures. With the exception of a few notable studies (e.g., Heil et al (1996);Heil (2006)), the role of sea/ocean temperature in fast-ice formation and decay has not been widely studied in either polar region, but in addition to lateral and basal melt, warm sea temperatures are likely to contribute to grounded keel erosion in the Arctic, leading to fast-ice breakout (Mahoney et al, 2007b). Ice keels play a key role in anchoring fast ice to the seabed in shallow Arctic coastal areas such as the north Alaskan coast.…”

Section: Fast-ice Response To Local Atmospheric Forcing: Work To Datementioning

confidence: 99%

“…• since fast-ice extent responds rapidly to both atmospheric and oceanic forcing (Mahoney et al, 2007b;Heil, 2006;Massom et al, 2009), it is probable that it is a sensitive indicator of climate change (Murphy et al, 1995;Mahoney et al, 2007a;Divine et al, 2003);…”

Section: The Importance Of Fast Icementioning

confidence: 99%

“…Mahoney et al (2007b) used a land-based marine radar situated at Point Barrow, Alaska, to study fast-ice formation and breakup events in unprecedented spatio-temporal resolution over a more limited area. George et al (2004) detailed observations (including anecdotes, weather station data and satellite images) of two unexpected fast-ice breakouts which threatened indigenous hunters in Arctic Alaska.…”

Section: Gaps In Our Knowledgementioning

confidence: 99%

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East Antarctic Landfast Sea Ice Distribution and Variability, 2000–08

et al. 2012

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This study presents the first continuous, high spatiotemporal resolution time series of landfast sea ice extent along the East Antarctic coast for the period March 2000–December 2008. The time series was derived from consecutive 20-day cloud-free Moderate Resolution Imaging Spectroradiometer (MODIS) composite images. Fast ice extent across the East Antarctic coast shows a statistically significant (1.43% ±0.30% yr−1) increase. Regionally, there is a strong increase in the Indian Ocean sector (20°–90°E, 4.07% ±0.42% yr−1), and a nonsignificant decrease in the western Pacific Ocean sector (90°–160°E, −0.40% ±0.37% yr−1). An apparent shift from a negative to a positive extent trend is observed in the Indian Ocean sector from 2004. This shift also coincides with a greater amount of interannual variability. No such shift in apparent trend is observed in the western Pacific Ocean sector, where fast ice extent is typically higher and variability lower than the Indian Ocean sector. The limit to the maximum fast ice areal extent imposed by the location of grounded icebergs modulates the shape of the mean annual fast ice extent cycle to give a broad maximum and an abrupt, relatively transient minimum. Ten distinct fast ice regimes are identified, related to variations in bathymetry and coastal configuration. Fast ice is observed to form in bays, on the windward side of large grounded icebergs, between groups of smaller grounded icebergs, between promontories, and upwind of coastal features (e.g., glacier tongues). Analysis of the timing of fast ice maxima and minima is also presented and compared with overall sea ice maxima/minima timing.

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Section: Fast-ice Response To Local Atmospheric Forcing: Work To Datementioning

confidence: 99%

Section: The Importance Of Fast Icementioning

confidence: 99%

Section: Gaps In Our Knowledgementioning

confidence: 99%

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East Antarctic Landfast Sea Ice Distribution and Variability, 2000–08

et al. 2012

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“…However, only draughts are reported in these data, hence values of the ice thickness are unknown, and we desire a method for estimating these from the draughts. Mahoney et al (2007) discuss such a method, noting that values of between 4.5 and 9 are reported in the literature for the ratio of keel depth to sail height, the latter value for an iceberg of constant density and porosity and the former for a pressure ridge having porous ice, snow and air pockets in the sail. For simplicity, we take the ratio to be 5 and assume that it will apply to all draughts, hence a thickness is 1.2 times the corresponding draught.…”

Section: (F ) Real Ice Draught Datamentioning

confidence: 99%

The decay of flexural-gravity waves in long sea ice transects

2009

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Flexural oscillations of floating sea ice sheets induced by ocean waves travelling at the boundary between the ice and the water below can propagate great distances. But, by virtue of scattering, changes of ice thickness and other properties encountered during the journey affect their passage, notwithstanding attenuation arising from several other naturally occurring agencies. We describe here a two-dimensional model that can simulate wave scattering by long (approx. 50 km) stretches of inelastic sea ice, the goal being to replicate heterogeneity accurately while also assimilating supplementary processes that lead to energy loss in sea ice at scales that are amenable to experimental validation. In work concerned with scattering from solitary or juxtaposed stylized features in the sea ice canopy, reflection and transmission coefficients are commonly used to quantify scattering, but on this occasion, we use the attenuation coefficient as we consider that it provides a more helpful description when dealing with long sequences of adjoining scatterers. Results show that scattering and viscosity both induce exponential decay and we observe three distinct regimes: (i) low period, where scattering dominates, (ii) high period, where viscosity dominates, and (iii) a transition regime. Each regime's period range depends on the sea ice properties including viscosity, which must be included for the correct identification of decay rate.

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“…in Okhotsk Sea in Tabata et al (1980), by matching of prominent features preserved from image to another; in the Chukchi Sea near Barrow, Alaska, in MV et al (2013), using Lucas-Kanade optical flow algorithm (Lucas and Kanade, 1981) for features detected by Harris corner/edge detection (Harris and Stephens, 1988) algorithm; and in the Baltic Sea in Karvonen (2013a), using a combination of phase correlation and normalized cross-correlation. Coastal radar data for sea ice analysis in the Canadian Arctic have been utilized in Shapiro (1976), Shapiro and Metzner (1989), Mahoney et al (2007), Druckenmiller et al (2009), andMahoney et al (2015).…”

Section: Introductionmentioning

confidence: 99%

Virtual radar ice buoys – a method for measuring fine-scale sea ice drift

Karvonen

2016

The Cryosphere

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Abstract.Here we present an algorithm for continuous ice drift estimation based on coastal and ship radar data. The ice drift is estimated for automatically selected ice targets in the images. These targets are here called virtual buoys (VBs) and are tracked based on an optical flow method. To maintain continuous ice drift tracking new VBs are added after a given number of VBs have been lost; i.e. they can not be tracked reliably any more. Here we also apply the algorithm to data of three test cases to demonstrate its capabilities and properties. Two of these cases use coastal radar data and one ship radar data. Ice drift velocity and direction information derived from the VB motion are computed and compared to the prevailing ice and weather conditions. Also a quantity measuring the local divergence or convergence is computed for some VBs to demonstrate the capability to estimate derived kinematic sea ice parameters from VB location time series. The results produced by the algorithm can be used as an input for estimation of the dynamic properties of sea the ice field, such as ice divergence or convergence, shear, vorticity, and total deformation.

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How fast is landfast sea ice? A study of the attachment and detachment of nearshore ice at Barrow, Alaska

Cited by 81 publications

References 23 publications

East Antarctic Landfast Sea Ice Distribution and Variability, 2000–08

East Antarctic Landfast Sea Ice Distribution and Variability, 2000–08

The decay of flexural-gravity waves in long sea ice transects

Virtual radar ice buoys – a method for measuring fine-scale sea ice drift

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