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.
Kenneth C. JEZEKBeata M. CSATHóUte C. HERZFELDKaty L. FARNESSPhilippe HUYBRECHTS
Snow/ice stratigraphic profile is one of the traditional and important research fields in glaciology. The profile drawn by hand, however, is a tough job. Using the Object Oriented Programming (OOP) Visual Basic (VB), we developed a Drawing Software for Snow/Ice Stratigraphic Profile (DSSISP). This paper introduces the functions, designing process and realizing methods of the drawing software. It presents the key techniques and aspects that should be payed attention to during the software development. Moreover, it also proposes the ideas for complete development of this drawing system. Legend database is a key aspect in the software designing. The major functions of the software include the stratigraphic profile drawing, edition and data management, which can help researchers draw the stratigraphic profile (including the scale, stratigraphic figure, text note and legend) quickly in a computer. In addition, the database technique is used to manage drawing data, which makes the figure drawing convenient and efficient. The drawing data is also convenient to be preserved, exchanged, processed and used.
It is well known that varying of the sea ice not only in the Antarctic but also in the Arctic has an active influence on the globe atmosphere and ocean. In order to understand the sea ice variation in detail, for the first time, an objective index of the Arctic and Antarctic sea ice variation is defined by projecting the monthly sea ice concentration anomalies poleward of 20°N or 20°S onto the EOF (empirical orthogonal function)-1 spatial pattern. Comparing with some work in former studies of polar sea ice, the index has the potential for clarifying the variability of sea ice in northern and southern high latitudes.
Climate anomalies in the southern high latitude associated with the Subtropical Dipole Mode (SDM) are investigated using a 23-year database consisting of SLP (sea level pressure), surface air temperature (SAT) and sea surface temperature (SST). The analysis depicts, for the first time, the spatial variability in the relationship of the above variables with the Subtropical Dipole Mode Index (SDI). It suggests that the SDM signal exists in the southern high latitudes and the correlation fields exhibit a wavenumber-3 pattern around the circumpolar Southern Ocean. Lead-lag correlation analysis used to the SLP, SAT, and SST anomalies with the SDI time series at the positive and negative correlation extremes shows that the southern-high-latitude climate responses to SDM almost instantaneously proposing the connection is by atmospheric and not by oceanic propagation.
