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Ice sheet thickness is determined mainly by the strength of ice‐bed coupling that controls holistic transitions from slow sheet flow to fast streamflow to buttressing shelf flow. Byrd Glacier has the largest ice drainage system in Antarctica and is the fastest ice stream entering Ross Ice Shelf. In 2004 two large subglacial lakes at the head of Byrd Glacier suddenly drained and increased the terminal ice velocity of Byrd Glacier from 820 m yr−1 to 900 m yr−1. This resulted in partial ice‐bed recoupling above the lakes and partial decoupling along Byrd Glacier. An attempt to quantify this behavior is made using flowband and flowline models in which the controlling variable for ice height above the bed is the floating fraction of ice along the flowband and flowline. Changes in before and after drainage are obtained from available data, but more reliable data in the map plane are required before Byrd Glacier can be modeled adequately. A holistic sliding velocity is derived that depends on , with contributions from ice shearing over coupled beds and ice stretching over uncoupled beds, as is done in state‐of‐the‐art sliding theories. Key Points The height of ice above the bed is determined mainly by ice‐bed coupling Uncoupling occurs mainly along ice streams which discharge up to 90% of ice Because of #1 and #2 ice sheets can rapidly self‐destruct

A longer temporal scale of Antarctic observations is vital to better understanding glacier dynamics and improving ice sheet model projections. One underutilized data source that expands the temporal scale is aerial photography, specifically imagery collected prior to 1990. However, processing Antarctic historical aerial imagery using modern photogrammetry software is difficult, as it requires precise information about the data collection process and extensive in situ ground control is required. Often, the necessary orientation metadata for older aerial imagery is lost and in situ data collection in regions like Antarctica is extremely difficult to obtain, limiting the use of traditional photogrammetric methods. Here, we test an alternative methodology to generate elevations from historical Antarctic aerial imagery. Instead of relying on pre-existing ground control, we use structure-from-motion photogrammetry techniques to process the imagery with manually derived ground control from high-resolution satellite imagery. This case study is based on vertical aerial image sets collected over Byrd Glacier, East Antarctica in December 1978 and January 1979. Our results are the oldest, highest resolution digital elevation models (DEMs) ever generated for an Antarctic glacier. We use these DEMs to estimate glacier dynamics and show that surface elevation of Byrd Glacier has been constant for the past ∼40 years.

P228.3%P332; 南极冰盖下流动水、活跃冰下湖的活动对冰动力学、接地线稳定性和冰盖物质平衡都有重要影响.本文结合ICESat和CryoSat-2测高卫星数据集,分别运用重复轨道法和差分DEM法,对Byrd冰川流域17个活跃冰下湖进行长达16年的监测,并计算其平均高程和平均水量变化,总结活跃冰下湖的水文特征.根据水势方程获取了此区域的冰下排水路径图,结合冰下湖的位置和活动情况分析其相互间的水文联系.结果表明Byrd冰川流域多个活跃冰下湖间存在明显的水文联系:Byrd1和Byrd2冰下湖具有以2～3年为周期的储排水活动规律,并且Byrd1冰下湖主要受到上游Byrd2冰下湖活动的影响;Byrds9和Byrds14分别受到上游Byrds11和Byrds15冰下湖排水的补充,使湖水水量持续上升.

A one-dimensional, numerical model of time-evolving firn densification was used to simulate the response of the density profile through an ice sheet to changes in the temperature, density and accumulation rate at the surface. The equilibrium response of the model was compared with ice-core density profiles from Byrd, Antarctica and Site 2, Greenland, and the model predicted the density to within 10% of both cores. The response of the model to step-wise changes and random fluctuations in the surface boundary conditions was investigated. The standard deviation of elevation changes as a function of observation interval was computed. These changes were found to be small in comparison with the magnitude of present uncertainties in the mass balances of the Antarctic and Greenland Ice Sheets. It was concluded that, in the dry snow zones, natural variability in the densification will not prevent the geodetic determination of ice sheet mass balance from improving upon current estimates. Uncertainty in the constitutive equation for snow and firn is the dominant source of error in the calculations.

[...]the naming of Dobbratz Glacier came about because Maj Dobbratz so impressed members of a geological research team from the University of Minnesota who were exploring and conducting experiments in the Ellsworth Mountains and nearby glaciers in the Heritage Range, that they personally and persistently petitioned authorities to have a particular glacier that they had discovered and mapped named for him. Eventually, they succeeded in their quest to honor their Marine resupply pilot and in December 1973, some nine years after departing Antarctica for the last time, while serving at the Pentagon in Washington, D.C., then-Lieutenant Colonel Dobbratz received a personal and unexpected letter from the International Coordinator of the National Science Foundation's Office of Polar Programs: \"It gives me great deal of pleasure to inform you that the U.S. Board on Geographic Names has named in your honor the geographic feature Dobbratz Glacier located at 79 24' S. latitude 85 05' W. longitude in the Heritage Range of the Ellsworth Mountains, Antarctica.\" According to the National GeospatialIntelligence Agency, Dobbratz Glacier is \"A broad tributary glacier which drains the S part of the White Escarpment and flows NE between Watlack Hills and Weber Peaks into Splettstoesser Glacier, in the Heritage Range.

One of the two bases that had been established in 1940 as part of the US government expedition to Antarctica, East Base, has survived as the oldest permanent US research station in Antarctica. Broadbent and Rose present an account of the reclaiming of East Base, its cleanup, its archaeology, and a discussion of its value as a physical record of American presence and scientific endeavor in Antarctica.