The climatic and environmental features on both sides of the Lambert Glacier Basin

During the 1992-1993 joint Australian-Chinese over-snow traverse of thewestern Lambert Glacier Basin (LGB), two firn cores were drilled respectively at MGA and LGB16.During the 1996-1997 and 1997-1998 austral summers, two firn cores were drilled respectively atDT001 and DT085 on the eastern LGB. Based on the measurements made during the expeditions, theclimatic and environmental features on both sides of the LGB have been studied. Results show thatduring the past 50 years, the trends of both air temperature and accumulation rate show a slightincrease on the east side of the LGB, in contrast to the west side of the LGB. The spatial trends ofthe accumulation rate measured by accumulation canes at 2 km intervals along the nearly 500 km ofthe traverse lines on both sides of the LGB are different. Moreover, correlations of δ^(18)O vsT_(10) along the two sides of the LGB are also different. In addition, the variations of sea saltion concentrations show different trends in the past 50 years. All the evidence shows that theLambert Glacier is a dividing region for the different climatic regimes over the East Antarctic icesheet, which may be due to different moisture resources resulting from special local circumfluencesuch as cyclone activities, local terrain influences.

Mass budgets of the Lambert, Mellor and Fisher Glaciers and basal fluxes beneath their flowbands on Amery Ice Shelf

We used in situ measurements and remote-sensing data sets to evaluate the mass budgets of the Lambert, Mellor and Fisher Glaciers and the basal melting and freezing rates beneath their flowbands on the Amery Ice Shelf. Our findings show the Lambert and Mellor Glaciers upstream of the ANARE Lambert Glacier Basin (LGB) traverse may have positive imbalances of 3.9±2.1 Gt a-1 and 2.1±2.4 Gt a-1, respectively, while the Fisher Glacier is approximately in balance. The upstream region as a whole has a positive imbalance of 5.9±4.9 Gt a-1. The three same glaciers downstream of the ANARE LGB traverse line are in negative imbalance, where the whole downstream region has a negative imbalance of -8.5±5.8 Gt a-1. Overall the mass budgets of the Lambert, Mellor, and Fisher Glaciers are close to bal-ance, and the collective three-glacier system is also nearly in balance with a mass budget of -2.6±6.5 Gt a-1. The significant positive imbalances for the interior basin upstream of the ice-movement stations established in the early 1970s (GL line) reported previously are possibly due to an overestimate of the total accumulation and an underestimate of the ice flux through the GL line. The mean melting rate is -23.0±3.5 m ice a-1 near the southern grounding line, which decreases rapidly downstream, and transitions to refreezing at around 300 km from the southern extremity of the Amery Ice Shelf. Freezing rates along the flowbands are around 0.5±0.1 to 1.5±0.2 m ice a-1. The per-centage of ice lost from the interior by basal melting beneath the flowbands is about 80%±5%. The total basal melting and refreezing beneath the three flowbands is 50.3±7.5 Gt ice a-1 and 7.0±1.1 Gt ice a-1, respectively. We find a much larger total basal melting and net melting than the results for the whole Amery Ice Shelf derived from previous modeling and oceanographic measurements.