Brief communication: Pancake ice floe size distribution during the winter expansion of the Antarctic marginal ice zone

Alberello, Alberto; Onorato, Miguel; Bennetts, Luke G.; Vichi, Marcello; Eayrs, Clare; MacHutchon, Keith; Toffoli, Alessandro

doi:10.5194/tc-13-41-2019

Cited by 62 publications

(95 citation statements)

References 27 publications

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“…Their absence has been used to infer consolidation of the pancakes into a compact ice cover (Doble & Wadhams, 2006). Our measurements of energetic waves (H S > 1.25 m) and intermittent internal sea ice deformations 100-200 km from the ice edge suggest that pancake ice conditions similar to the ones at deployment (Alberello, Onorato, Bennetts, et al, 2019) persisted for at least the first 7 days following deployment, beyond which ice conditions may have transformed as the ice edge advanced.…”

Section: Discussionmentioning

confidence: 81%

Drift of Pancake Ice Floes in the Winter Antarctic Marginal Ice Zone During Polar Cyclones

et al. 2020

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High temporal resolution in situ measurements of pancake ice drift are presented, from a pair of buoys deployed on floes in the Antarctic marginal ice zone during the winter sea ice expansion, over 9 days in which the region was impacted by four polar cyclones. Concomitant measurements of wave‐in‐ice activity from the buoys are used to infer that the ice remained unconsolidated, and pancake ice conditions were maintained over at least the first 7 days. Analysis of the data shows (i) the fastest reported ice drift speeds in the Southern Ocean; (ii) high correlation of drift velocities with the surface wind velocities, indicating absence of internal ice stresses >100 km from the ice edge where remotely sensed ice concentration is 100%; and (iii) presence of a strong inertial signature with a 13 hr period. A Lagrangian free drift model is developed, including a term for geostrophic currents that reproduce the 13 hr period signature in the ice motion. The calibrated model provides accurate predictions of the ice drift for up to 2 days, and the calibrated parameters provide estimates of wind and ocean drag for pancake floes under storm conditions.

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Section: Discussionmentioning

confidence: 81%

Drift of Pancake Ice Floes in the Winter Antarctic Marginal Ice Zone During Polar Cyclones

et al. 2020

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“…The zero-S ice simulation apparently overestimates H s,3 even for very low C I cases (blue points in Fig. 4c), indicating some small-scale ice features (e.g., ice melt and drift; Smith et al 2018;Alberello et al 2020), which could affect the attenuation of waves dramatically (Sutherland et al 2018), was unresolved by the AMSR2 C I data and our constant h i assumption. For moderate C I (pink points), the full M2 model is in good agreement with observations ( Fig.…”

Section: A R/v Sikuliaq Cruise 2015mentioning

confidence: 87%

“…The three sea ice models we select are intuitively appealing as a MIZ composed of numerous ice floes, pancake ice, and frazil present at different sizes (e.g., Alberello et al 2019) is mapped onto a modified dispersion relation with one/two rheological parameters only. These models, particularly the two VE ones, however, are practically difficult in the sense that estimating effective G and h for different ice covers requires tremendous efforts since these parameters could vary over several orders of magnitude (section S4; see also Cheng et al 2017).…”

Section: Limitations and Operational Forecastmentioning

confidence: 99%

Spectral Modeling of Ice-Induced Wave Decay

Liu

Rogers

Babanin

et al. 2020

Journal of Physical Oceanography

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Three dissipative (two viscoelastic and one viscous) ice models are implemented in the spectral wave model WAVEWATCH III to estimate the ice-induced wave attenuation rate. These models are then explored and intercompared through hindcasts of two field cases: one in the autumn Beaufort Sea in 2015 and the other in the Antarctic marginal ice zone (MIZ) in 2012. The capability of these dissipative models, along with their limitations and applicability to operational forecasts, are analyzed and discussed. The sensitivity of the simulated wave height to different source terms—the ice-induced wave decay Sice and other physical processes Sother (e.g., wind input, nonlinear four-wave interactions)—is also investigated. For the Antarctic MIZ experiment, Sother is found to be remarkably less than Sice and thus contributes little to the simulated significant wave height Hs. The saturation of dHs/dx at large wave heights in this case, as reported by a previous study, is well reproduced by the three dissipative ice models with or without the utilization of Sother in the ice-infested seas. A clear downward trend in the peak frequency fp is found as Hs increases. As fp decreases, the dominant wave components of a wave spectrum will experience reduced damping by sea ice, and finally result in the flattening of dHs/dx for Hs > 3 m in this specific case. Nonetheless, Sother should not be disregarded within a more general modeling perspective, as our simulations suggest Sother could be comparable to Sice in the Beaufort Sea case where wave and ice conditions are remarkably different.

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“…To proceed and arrive at a concrete (although not general) realization of these functions, we will assume all floes are perfect circles. In assessments of the relationship between major and minor axes of individual floes, the "roundness" parameter for a floe is typically within 15% of one (Rothrock and Thorndike, 1984b;Toyota et al, 2011;Perovich and Jones, 2014;Gherardi and Lagomarsino, 2015;Alberello et al, 2019), suggesting that this circular assumption, while simplistic, is broadly appropriate. Nevertheless, it will likely be necessary to amend the analysis below in the future to account for more realistic shape distributions and geometries (e.g., diamonds (Wilchinsky and Feltham, 2006)), or to evaluate the sensitivity of the results that follow to the assumed shape distribution.…”

Section: Floe Chords and The Floe Size Distributionmentioning

confidence: 99%

Estimating The Sea Ice Floe Size Distribution Using Satellite Altimetry: Theory, Climatology, and Model Comparison

Horvat¹,

Roach²,

Tilling³

et al. 2019

Preprint

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Abstract. In sea-ice-covered areas, the sea ice floe size distribution (FSD) plays an important role in many processes affecting the coupled sea-ice-ocean-atmosphere system. Observations of the FSD are spare – traditionally taken via a pain-staking analysis of ice surface photography – and the seasonal and inter-annual evolution of floe size regionally and globally is largely unknown. Frequently, measured FSDs are assessed using a single number, the scaling exponent of the closest power law fit to the observed floe size data, although in the absence of adequate datasets there have been limited tests of this power-law hypothesis. Here we derive and explain a mathematical technique for deriving statistics of the sea ice FSD from polar-orbiting altimeters, satellites with sub-daily return times to polar regions with high along-track resolutions. Applied to the CryoSat-2 radio altimetric record, covering the period from 2010–2018, and incorporating 11 million individual floe samples, we produce the first climatology and seasonal cycle of sea ice floe size statistics. We then perform the first pan-Arctic test of the power law hypothesis, finding limited support in the range of floe sizes typically analyzed in photographic observational studies. We compare the seasonal variability in observed floe size to fully coupled climate model simulations including a prognostic floe size and thickness distribution and coupled wave model, finding good agreement in regions where modeled ocean surface waves cause sea ice fracture.

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Brief communication: Pancake ice floe size distribution during the winter expansion of the Antarctic marginal ice zone

Cited by 62 publications

References 27 publications

Drift of Pancake Ice Floes in the Winter Antarctic Marginal Ice Zone During Polar Cyclones

Drift of Pancake Ice Floes in the Winter Antarctic Marginal Ice Zone During Polar Cyclones

Spectral Modeling of Ice-Induced Wave Decay

Estimating The Sea Ice Floe Size Distribution Using Satellite Altimetry: Theory, Climatology, and Model Comparison

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