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Rapid ice mass variations within the large polar ice sheets lead to distinct and highly non-uniform sea-level changes that
have come to be known as ‘sea-level fingerprints’. We explore in detail the physics of these fingerprints by decomposing the
total sea-level change into contributions from radial perturbations in the two bounding surfaces: the geoid (or sea surface)
and the solid surface. In the case of a melting event, the sea-level fingerprint is characterized by a sea-level fall in the
near-field of the ice complex and a gradually increasing sea-level rise (from 0.0 to 1.3 times the eustatic value) as one
considers sites at progressively greater distances (up to ≈ 90° or so) from the ice sheet. The far-field redistribution is
largely driven by the relaxation of the sea-surface as the gravitational pull of the ablating ice sheet weakens. The near-field
sea-level fall is a consequence of both this relaxation and ocean-plus-ice unloading of the solid surface. We argue that the
fingerprints provide a natural explanation for geographic variations in sea-level (e.g., tide gauge, satellite) observations.
Therefore, they furnish a methodology for extending traditional analyses of these observations to estimate not only the globally
averaged sea-level rate but also the individual contributions to this rate (i.e., the sources).
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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D Milne K O'Sullivan 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1994,14(8):451-458
Young students find extra-terrestrial life one of the most intriguing of all topics. A project funded by the National Science Foundation and NASA, and administered by the SETI Institute, is underway to devise science lessons for grades 3-9 that draw upon this fascination. The lessons are designed by teachers and persons with long experience at curriculum design, tested in classrooms, revised and retested. Six guides, each containing some 6-10 science lessons, will be finished by summer, 1994. The theme Life in the Universe lends itself naturally to integrated treatment of facts and concepts from many scientific disciplines. The lessons for two completed guides span the origin of planet systems, evolution of complex life, chemical makeup of life, astronomy, spectroscopy, continental drift, mathematics and SETI (Search for Extra-Terrestrial Intelligence). All lessons are hands-on, interesting, and successful. 相似文献
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