The Drainage Systems of Antarctica: Accumulation

Giovinetto, Mario B.

doi:10.1029/ar002p0127

Cited by 8 publications

(3 citation statements)

References 21 publications

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“…We use ¯  ice j−1 for the latter term, along with a gross mass loss term that is determined by gross accumulation minus net accumulation/loss (where loss is negative). Net accumulation/loss is obtained from sea level variations, and gross accumulation (a grs ) is calculated in an ice sheet surfacearea-dependent manner directly proportional to modern global annual a grs of ~0.008 m seq [following rates in (44,45)] for a global ice volume of 65.1 m seq .…”

Section: Applied Assessmentsmentioning

confidence: 99%

“…To calculate the volume-weighted mean  ice (i.e., ¯  ice ) for each ice sheet, we use a residence-time calculation. This starts with ice sheet gross accumulation rate (a grs ) determination based on the area defined by its volume (with constant aspect ratio ), simply scaled in proportion to a modern global annual a grs of ~0.008 m seq (44,45) for a global ice volume of 65.1 m seq . Volume is obtained in relation to  SL according to Eqs.…”

Section: Individual Ice Sheet Volume Historiesmentioning

confidence: 99%

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Sea level and deep-sea temperature reconstructions suggest quasi-stable states and critical transitions over the past 40 million years

et al. 2021

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Sea level and deep-sea temperature variations are key indicators of global climate changes. For continuous records over millions of years, deep-sea carbonate microfossil–based δ18O (δc) records are indispensable because they reflect changes in both deep-sea temperature and seawater δ18O (δw); the latter are related to ice volume and, thus, to sea level changes. Deep-sea temperature is usually resolved using elemental ratios in the same benthic microfossil shells used for δc, with linear scaling of residual δw to sea level changes. Uncertainties are large and the linear-scaling assumption remains untested. Here, we present a new process-based approach to assess relationships between changes in sea level, mean ice sheet δ18O, and both deep-sea δw and temperature and find distinct nonlinearity between sea level and δw changes. Application to δc records over the past 40 million years suggests that Earth’s climate system has complex dynamical behavior, with threshold-like adjustments (critical transitions) that separate quasi-stable deep-sea temperature and ice-volume states.

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Section: Applied Assessmentsmentioning

confidence: 99%

Section: Individual Ice Sheet Volume Historiesmentioning

confidence: 99%

Sea level and deep-sea temperature reconstructions suggest quasi-stable states and critical transitions over the past 40 million years

et al. 2021

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“…As the largest ice shelf in East Antarctic Ice Sheet, the Amery Ice Shelf (AIS) buttresses the Lambert Glacier Basin which constitutes the fourth largest drainage system in Antarctica (Giovinetto, 1964;McIntyre, 1985) draining approximately 12.5% of the Antarctic Ice Sheet (Drewry, 1983). Lambert Glacier and other two primary tributary glaciers transport ice from the interior Lambert Glacier Basin through the southern grounding line of the AIS discharging into the Prydz Bay.…”

Section: Introductionmentioning

confidence: 99%

Inter-and Intra-annual Surface Velocity Variations at the Southern Grounding Line of Amery Ice Shelf from 2014 to 2018

Chi

Klein

2020

Preprint

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Abstract. The ice flow rate through the grounding line of the Amery Ice Shelf (AIS) is vital to understanding the mass discharge received from its three primary tributary glaciers. Previous studies have indicated a stable multiyear average surface velocity distribution in the convergence area of AIS. However, the surface velocity variations, especially short-term fluctuations, in the AIS have been relatively undocumented. This study investigated inter-annual and intra-annual surface velocity variations along the southern segment of AIS grounding line from 2014 to 2018. Using feature tracking to derive surface velocity for five consecutive austral summers and winters, it was found that AIS’s upstream end has experienced a steady ~ 5 % inter-annual increase in surface velocity. Surface velocity increases were observed in 2014/2015 (0.25 ± 0.02 m/d) and in 2017/2018 (0.21 ± 0.02 m/d) respectively. Surface velocities in winters were lower than the summers except for 2016, which had a 0.12 m/d surface velocity decrease from winter to summer. Although flowing slower than the other two glaciers, Fisher Glacier exhibited the highest inter-annual increase (8.56 ± 4.36 %) and the largest intra-annual variation (−5.41 ± 5.65 %) in surface velocity of the three studied glaciers. While the surface velocity observed in 2018 was generally close to the observed velocity in 1989, the magnitude of velocity variations observed during the 2014–2018 period is similar to the differences in velocities measured at the grounding line since 1989. This indicates continued relative stability in the surface velocities at the grounding line of these three tributary glaciers but also indicates that caution should be applied when interpreting long-term differences based on a limited number of measurements. This study demonstrated the capability of feature tracking to monitor the multidecadal changes of surface velocity.

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Concerning the Deposition and Diagenesis of Strata in Polar Firn

Alley

1988

J. Glaciol.

112

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ABSTRACT. Depth hoar in polar fim forms when large temperature gradients act on low-density firn, but high-density firn does not develop into depth hoar. Low densities in firn may be depositional (burial of surface hoar or still-air snowfall) or diagenetic (mass loss to the freE( atmosphere, typically in autumn); however, diagenesis is sufficiently strong to cause significant mass loss only in the top 50-100 mm of fim. Between about 50-100 mm and 2 m depth, grain growth and densification are accelerated strongly by temperature-gradient effects; from 2 to 5 m, temperature gradients have a small but measurable effect on rates of processes in fim, and below 5 m rates essentially have isothermal values.Diagenetic depth-hoar layers typically develop in the autumn, are relatively thick, and have smooth bases.

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The Drainage Systems of Antarctica: Accumulation

Cited by 8 publications

References 21 publications

Sea level and deep-sea temperature reconstructions suggest quasi-stable states and critical transitions over the past 40 million years

Sea level and deep-sea temperature reconstructions suggest quasi-stable states and critical transitions over the past 40 million years

Inter-and Intra-annual Surface Velocity Variations at the Southern Grounding Line of Amery Ice Shelf from 2014 to 2018

Concerning the Deposition and Diagenesis of Strata in Polar Firn

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