David Glacier Research Articles

Glaciological study in Terra Nova Bay, Antarctica, inferred from remote sensing analysis

Analysis of satellite images (Landsat 1 MSS, 4 TM and SPOT 1 XS), of U.S. Navy aerial photographs (TMA) and of U.S.G.S. maps has made it possible to assess a number of parameters relating to the surface dynamics (between 1956 and 1990) of eight ice tongues and of two ice shelves in the Terra Nova Bay area. The study shows that between 1960–63 and 1972–73 there was a decided decrease in the areas of some of the tongues and shelves: −53 km2 for the Aviator Glacier Tongue and −124 km2 for the Nansen Ice Sheet. On the other hand, the areas generally increased in the period 1972–73 to 1988. An exception to this situation is the small Hells Gate ice shelf whose area diminished by 1.15 km2 between 1956–57 and 1988. The calculated surface velocity of the ice tongues shows that they increase from the grounding line to their outer limit. Values of longitudinal strain rate generally increase from the grounding line to just after the start of the ice tongue, after which they diminsh proceeding towards its outer limit. Integration of the areal values with radio-echo sounding data has enabled the ice discharges of the southern flow of the David Glacier (12km3a−1) and of the Aviator Glacier Tongue (0.62 km3 a−1) to be calculated. Furthermore, on the basis of the data available, basal melting values of between 25 cm a−1 and 100 cm a−1 are deduced for these two ice tongues, and bottom freezing values of 20 cm a−1 for the Drygalski Ice Tongue. Different spectral responses of the glacial areas have made it possible to discriminate ablation areas from those of accumulation and to differentiate various typologies of ice (glacier ice, melt lake ice, and sea ice formed at the ice shelf-ocean interface).

The confluence zone of the intense katabatic winds at Terra Nova Bay, Antarctica, as derived from airborne sastrugi surveys and mesoscale numerical modeling

The surface wind field inland of the intense coastal katabatic wind regime at Terra Nova Bay, Antarctica, has been studied both observationally and numerically. Airborne surveys of wind‐induced features on the snow surface have been used to construct the time‐averaged winter surface airflow pattern. The surface motion field has also been simulated by a mesoscale primitive equation model using terrain slopes with a horizontal resolution of 32 km. Both methods of analysis demonstrate that the intense katabatic airstream at Terra Nova Bay is forced by converging air currents in the continental interior. The broadscale confluence zone becomes organized into two regions within about 180 km of the coast. The primary route for katabatic mass transport into the Terra Nova Bay area is Reeves Glacier valley, but an important secondary source is provided by airflow down David Glacier. The former is generated by the Coriolis‐induced concentration of mass transport on the left side (looking downwind) of the broadscale confluence zone as well as by the near‐coastal mountain deflection of airflow into the valley head. The confluence zone feeding into David Glacier valley stretches over 100 km into the interior and is forced by the broadscale terrain configuration of the ice sheet. Source areas for the two airstreams diner with Reeves Glacier valley being fed by cold air formed well into the interior, whereas the airflow down David Glacier is sustained by radiative cooling over lower parts of the ice sheet which are much closer to the Ross Sea. Evaluation of the observational and modeling results reveals both the strengths and weaknesses of each approach. Airborne surveys of sastrugi orientations are a highly successful method for establishing the detailed pattern of surface airflow. However, a systematic examination of sastrugi dimensions suggests that such work could also be carried out using SPOT‐type satellite observations, which is a more cost‐effective approach than aircraft surveying. The double‐jet structure of katabatic airflow into the Terra Nova Bay area is well represented by the primitive equation modeling, but much finer grids are needed to resolve the near‐coastal drainage details.

Ice-Sheet flow in the Vicinity of Southern Victoria Land, Antarctica: Implications for Glacial Chronology

AbstractSystematic radio echo-sounding during three seasons since 1971–72 has produced data on the configuration of the ice sheet in East Antarctica. In the sector extending inland from southern Victoria Land, the ice sheet exhibits a large ridge which drives ice towards David Glacier in the north and Mulock and Byrd Glaciers to the south. Within 100 km of the McMurdo dry-valley region soundings along ten sub-parallel lines (c. 10 km apart) provides detail on ice surface and flow patterns at the ridge tip. A small surface dome lies just inland of Taylor Glacier. The surface drops by 100 m or more before rising to join the major ridge in East Antarctica.

Ice-Sheet flow in the Vicinity of Southern Victoria Land, Antarctica: Implications for Glacial Chronology

Abstract Systematic radio echo-sounding during three seasons since 1971–72 has produced data on the configuration of the ice sheet in East Antarctica. In the sector extending inland from southern Victoria Land, the ice sheet exhibits a large ridge which drives ice towards David Glacier in the north and Mulock and Byrd Glaciers to the south. Within 100 km of the McMurdo dry-valley region soundings along ten sub-parallel lines (c. 10 km apart) provides detail on ice surface and flow patterns at the ridge tip. A small surface dome lies just inland of Taylor Glacier. The surface drops by 100 m or more before rising to join the major ridge in East Antarctica.