QUANTITATIVE IDENTIFICATION OF ANTARCTIC FIRST YEAR PRESSURE RIDGES AND PRELIMINARY RESULTS ON RIDGE MORPHOLOGY

摘要

We developed a quantitative scheme for identifying Antarctic first year ridge sails and keels from 204 drill profiles obtained from the Weddell, Ross, Amundsen and Bellingshausen Seas. A sail is defined as a non-level section on the top surface which has at least one point which is >0.3m above the surrounding level top surface. A keel is defined as a non-level section on the bottom surface which has at least one point which is >2.25 times as thick as the surrounding mean level ice thickness. From nearly 19km of drill data we identified 48 ridges. Almost 65% of them are not associated with any sails, while a small proportion overlap with two sails. The ratio between maximum snow sail height and maximum ice keel depth is 1:3.6. Estimating the volume of a ridge by assuming it has the same thickness as the surrounding level ice, underestimates by approximately 40%. Estimation of mass contained within keels from snow sail statistics must take into account the probability of a keel being associated with a sail and the ratios between the snow sail and ice keel.