Multi-satellite determination of global and regional geoid and sea level variations

点击翻译按钮获取中文摘要

Canada and the US have recently decided to establish geoid-based vertical datums by 2010 and 2018, respectively. The geoid is the equipotential surface of the idealized oceans at rest and thus serves as the reference surface (datum) for elevations. Therefore, its precise determination and refinement is an on-going subject of research in geodesy, as it is indispensable in mapping, navigation, oceanography, geo-referencing of spatial data and geo-hazards monitoring, and for studying the physics of the Earth's interior, sea level changes, ocean circulation, ice motion, and climate changes. A vertical datum requires precise knowledge of the geoid, the Earth's crust and the mean sea surface, together with their variations in time. Such knowledge can only be obtained by combining space-borne observations with other terrestrial/oceanic information. Of primary importance are the data provided by satellites dedicated (a) to the determination of the Earth's gravity field (CHAMP, GRACE, and the soon-to-be-launched GOCE) and (b) to the monitoring of the Earth's oceans and ice caps (various laser altimetry satellites, the soon-to-be-launched CryoSat-2, etc.). The abundance of such data presently and in the future provides tremendous opportunities for advancing geodetic research and its applications. Therefore, the main goal, and expected outcome, of the proposed research is to enhance Canada's capacity in remote sensing of the Earth system by developing methods for the joint exploitation of data from various Earth-observing satellites for ocean circulation monitoring and gravity field determination. The first major objective is to determine an accurate high-resolution geoid at continental and global scales, and its temporal and error characteristics. For the second major objective, multi-satellite sea and ice altimetry data from current and future missions will be merged to compute a high-resolution mean sea surface and the contribution of ice sheets to the mean global rise in sea level. Combining both objectives will lead to the successful establishment of a geoid-based vertical datum. Other important outcomes of this research will be the use of GRACE and other data for hydrology studies and for postglacial rebound determination in Canada.