Observing the disintegration of the A68A iceberg from space

Braakmann-Folgmann, Anne; Shepherd, Andrew; Gerrish, Laura; Izzard, Jamie; Ridout, A.

doi:10.1016/j.rse.2021.112855

Cited by 12 publications

(20 citation statements)

References 52 publications

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“…In contrast with the sea ice melt anomalies, which covered a very broad area of the northern Weddell Sea, the melt anomalies from the giant A68 iceberg were much more localized. While the iceberg discharged a considerable quantity of freshwater to the ocean (802 ± 34 Gt of ice was lost from A68a in 3.5 y [ 9 ]), this still represents a comparatively small flux given the spatial scales over which the freshwater is distributed. If salinity measurements alone were available, it would not have been straightforward to trace the meltwater from the iceberg: the salinities of the waters were largely (though not entirely) encompassed within the typical range of salinities at this location ( figure 12 ).…”

Section: Discussionmentioning

confidence: 99%

“…The source of this anomaly is meltwater from the giant iceberg A68, which originated in the Weddell Sea and traversed the Scotia Sea in the period preceding the timing of the 2021 A23 cruise (blue in figure 10 d , e ). By the time A68 had reached the vicinity of South Georgia, it had lost considerable mass [ 9 ] and had begun disintegrating into multiple pieces ( figure 11 ). In addition to the routine A23 stations, extra CTD stations were occupied on cruise JC211 in the vicinity of these iceberg fragments, with the purpose of tracing and quantifying meltwater injection to the ocean.…”

Section: Meteoric Water Distribution and Changesmentioning

confidence: 99%

“…Meltwater from glaciers and ice shelves is injected at the coast and can be a source of the micronutrients that stimulate productivity [ 7 , 8 ]. Glacial melt can also be injected at distance from Antarctica via the calving, advection and progressive melt of icebergs [ 9 ]; these can modulate stratification locally and have the potential to enhance phytoplankton growth in their wake [ 10 , 11 ]. Precipitation can enter the ocean directly as snowfall or rainfall, or via accumulation on sea ice or at coastal sites with subsequent seasonal melt [ 12 ].…”

Section: Introductionmentioning

confidence: 99%

“…Although not well constrained by observations, high-latitude precipitation is likely to increase in a warming climate, consistent with an increase in the capacity of warmer air to hold and transport moisture [ 20 ]. The impact of icebergs has been the focus of significant attention recently, due at least partly to the gigantic (initially 5719 ± 77 km 2 ) A68 iceberg that calved in 2017, and that exited the Weddell Sea and reached the shelf of South Georgia before disintegrating in 2021 [ 9 , 21 ].…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Tracing the impacts of recent rapid sea ice changes and the A68 megaberg on the surface freshwater balance of the Weddell and Scotia Seas

Meredith

Abrahamsen

Haumann

et al. 2023

Phil. Trans. R. Soc. A.

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The Southern Ocean upper-layer freshwater balance exerts a global climatic influence by modulating density stratification and biological productivity, and hence the exchange of heat and carbon between the atmosphere and the ocean interior. It is thus important to understand and quantify the time-varying freshwater inputs, which is challenging from measurements of salinity alone. Here we use seawater oxygen isotopes from samples collected between 2016 and 2021 along a transect spanning the Scotia and northern Weddell Seas to separate the freshwater contributions from sea ice and meteoric sources. The unprecedented retreat of sea ice in 2016 is evidenced as a strong increase in sea ice melt across the northern Weddell Sea, with surface values increasing approximately two percentage points between 2016 and 2018 and column inventories increasing approximately 1 to 2 m. Surface meteoric water concentrations exceeded 4% in early 2021 close to South Georgia due to meltwater from the A68 megaberg; smaller icebergs may influence meteoric water at other times also. Both these inputs highlight the importance of a changing cryosphere for upper-ocean freshening; potential future sea ice retreats and increases in iceberg calving would enhance the impacts of these freshwater sources on the ocean and climate. This article is part of a discussion meeting issue ‘Heat and carbon uptake in the Southern Ocean: the state of the art and future priorities’.

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Section: Discussionmentioning

confidence: 99%

Section: Meteoric Water Distribution and Changesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Tracing the impacts of recent rapid sea ice changes and the A68 megaberg on the surface freshwater balance of the Weddell and Scotia Seas

Meredith

Abrahamsen

Haumann

et al. 2023

Phil. Trans. R. Soc. A.

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“…It is worth mentioning that remote sensing technology has been widely used to assess different aspects of iceberg properties comprising iceberg detection and iceberg trajectory (Lopez-Lopez et al, 2021;Braakmann-Folgmann et al, 2022), iceberg drift (Monteban et al, 2020), and iceberg draft (Liu et al, 2021). The geometrical properties of the exposed part of the icebergs are obtained from remote sensing studies.…”

Section: Comparison With the Previous Modelsmentioning

confidence: 99%

Determination of Parameters Affecting the Estimation of Iceberg Draft

2023

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Recent offshore oil and gas loading facilities developed in the Arctic area have led to a considerable awareness of the iceberg draft approximation, where deep keel icebergs may gouge the ocean floor, and these submarine infrastructures would be damaged in the shallower waters. Developing reliable solutions to estimate the iceberg draft requires a profound understanding of the problem’s dominant parameters. As such, the dimensionless groups of the parameters affecting the iceberg draft estimation were determined for the first time in the present study. Using the dimensionless groups recognized and the linear regression (LR) analysis, nine LR models (i.e., LR 1 to LR 9) were developed and then validated using a comprehensive dataset, which has been constructed in this study. A sensitivity analysis distinguished the premium LR models and important dimensionless groups. The best LR model, as a function of all dimensionless parameters, was able to estimate the iceberg draft with the highest level of precision and correlation along with the lowest degree of complexity. The ratio of iceberg length to iceberg height as the “iceberg length ratio” and the ratio of iceberg width to iceberg height as the “iceberg width ratio” was detected as the important dimensionless groups in the estimation of the iceberg draft. An uncertainty analysis demonstrated that the best LR model was biased towards underestimating the iceberg drafts. The premium LR model outperformed the previous empirical models. Ultimately, a set of LR-based relationships were derived for estimating the iceberg drafts for practical engineering applications, e.g., the early stages of the iceberg management projects.

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Quantifying dissolution rates of Antarctic icebergs in open water

et al. 2023

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At any one time 130 000 icebergs are afloat in the Southern Ocean; 97% of these are too small to be registered in current satellite-based databases, yet the melting of these small icebergs provides a major input to the Southern Ocean. We use a unique set of visual size observations of 53 000 icebergs in the South Atlantic Ocean, the SCAR International Iceberg Database, to derive average iceberg dissolution rates. Fracture into two parts is the dominant dissolution process for tabular icebergs, with an average half-life of 30 days for icebergs <4 km length and 60 days for larger icebergs. Complete shatter producing many icebergs <1 km length is rare. A side attrition rate of 0.23 m d−1 combined with drift speed of 6 km d−1, or any proportional change in both numbers fits the observed changes in iceberg distribution. The largest injection into the Southern Ocean of fresh water and any iceberg-transported material takes place in a ~2.3 × 10⁶ km2 zone extending east-northeast from the Antarctic Peninsula to the Greenwich meridian. The iceberg contribution to salinities and temperatures, with maximum contribution north of the Weddell Sea, differs in some regions, from those indicated by tracking large icebergs.

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Observing the disintegration of the A68A iceberg from space

Cited by 12 publications

References 52 publications

Tracing the impacts of recent rapid sea ice changes and the A68 megaberg on the surface freshwater balance of the Weddell and Scotia Seas

Tracing the impacts of recent rapid sea ice changes and the A68 megaberg on the surface freshwater balance of the Weddell and Scotia Seas

Determination of Parameters Affecting the Estimation of Iceberg Draft

Quantifying dissolution rates of Antarctic icebergs in open water

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