Ice flow dynamics, subglacial hydrology and long-term mass balanceat Lake Vostok from the combination of geodetic GNSS observationsand radio-echo sounding

点击翻译按钮获取中文摘要

This proposal aims at a focused analysis, interpretation and publication of a unique set of geodetic and geophysical in-situobservations in the region of subglacial Lake Vostok, central East Antarctica. These data have been obtained by the applicant and his cooperation partner during nine field expeditions since 2001 up to now. Based on repeated satellite positioning on surface markers the velocity and direction of ice flow across the subglacial lake shall be investigated. The particular conditions in this region limit the applicability of remote sensing techniques and ice-dynamic modelling and make geodetic insitu observations the most reliable source of information. Special attention will be paid to the transition from grounded to floating ice across the lake's shore where preliminary observational results contradict current theoretical considerations. Furthermore, the variability of ice flow in the Lake Vostok region over climatic timescales shall be constrained by a combination of geodetic observations at the surface with the geometry of internal ice layers. In addition, different geodetic techniques shall be combined to separate and quantify the contributions of local ice-mass balance, water volume changes and water movements within the subglacial lake to observable height changes. The largest subglacial lake on Earth represents a particularly promising target for the geodetic determination of ice-flow velocities and height changes. These observations allow insights into the complex interactions between ice, subglacial water and bedrock and interpretations regarding different processes within the lake. Moreover, observational constraints on thepresent and past ice-flow regime are crucial for the interpretation of the ice core retrieved at Vostok station. The results of this project shall be combined in a time-integrating model for the Vostok flowline that determines where ice samples of the core of a certain age were formed. This will contribute to the improvement of the multidisciplinary interpretation of the Vostok ice core that is relevant not only for the understanding of the Lake Vostok system, but also for research on continental and global scales. Although the emphasis is given on the utilization of existing data, the fieldwork shall be continued throughout the project duration to ensure the continuity of the geodetic monitoring. This is a cooperation project with Dr. Sergey V. Popov (PMGE, St. Petersburg) in the frame of the MoU between DFG and the Russian Foundation of Basic Research (RFBR).