| 1. |
- Poutanen, Markku, et al.
(författare)
-
DynaQlim – Upper Mantle Dynamics and Quaternary Climate in Cratonic Areas
- 2010
-
Ingår i: New Frontiers in Integrated Solid Earth Sciences. - Dordrecht : Springer. - 9789048127368 - 9789048127375 ; , s. 349-372
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The isostatic adjustment of the solid Earth to the glacial loading (GIA, Glacial Isostatic Adjustment) with its temporal signature offers a great opportunity to retrieve information of Earth’s upper mantle to the changing mass of glaciers and ice sheets, which in turn is driven by variations in Quaternary climate. DynaQlim (Upper Mantle Dynamics and Quaternary Climate in Cratonic Areas) has its focus to study the relations between upper mantle dynamics, its composition and physical properties, temperature, rheology, and Quaternary climate. Its regional focus lies on the cratonic areas of northern Canada and Scandinavia.Geodetic methods like repeated precise levelling, tide gauges, high-resolution observations of recent movements, gravity change and monitoring of postglacial faults have given information on the GIA process for more than 100 years. They are accompanied by more recent techniques like GPS observations and the GRACE and GOCE satellite missions which provide additional global and regional constraints on the gravity field. Combining geodetic observations with seismological investigations, studies of the postglacial faults and continuum mechanical modelling of GIA, DynaQlim offers new insights into properties of the lithosphere. Another step toward a better understanding of GIA has been the joint inversion of different types of observational data – preferentially connected with geological relative sea-level evidence of the Earth’s rebound during the last 10,000 years.Due to the changes in the lithospheric stress state large faults ruptured violently at the end of the last glaciation in large earthquakes, up to the magnitudes MW = 7–8. Whether the rebound stress is still able to trigger a significant fraction of intraplate seismic events in these regions is not completely understood due to the complexity and spatial heterogeneity of the regional stress field. Understanding of this mechanism is of societal importance.Glacial ice sheet dynamics are constrained by the coupled process of the deformation of the viscoelastic solid Earth, the ocean and climate variability. Exactly how the climate and oceans reorganize to sustain growth of ice sheets that ground to continents and shallow continental shelves is poorly understood. Incorporation of nonlinear feedback in modelling both ocean heat transport systems and atmospheric CO2 is a major challenge. Climate-related loading cycles and episodes are expected to be important, hence also more short-term features of palaeoclimate should be explicitly treated.Within this Chapter View ChapterIntroductionObservational BasisCurrent Models and Problems to be SolvedClimateChallenges with DynaQlimReferencesReferencesOther actionsExport citationsAbout this BookReprints and Permissions
|
|
| 2. |
- Timmen, Ludger, et al.
(författare)
-
Observing Fennoscandian Gravity Change by Absolute Gravimetry
- 2006
-
Ingår i: International Association of Geodesy Symposia, Vol. 131, Geodetic Deformation Monitoring: From Geophysical to Engineering Roles. ; , s. 193-199
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The Nordic countries Norway, Sweden, Denmark and Finland are a key study region for the research of glacial isostasy, and, in addition, it offers a unique opportunity for validating and testing the results of the GRACE experiment. Over a period of five years, the expected life time of GRACE, a temporal geoid variation of 3.0 mm is expected in the centre of the Fennoscandian land uplift area, corresponding to a gravity change of about 100 nm/s2. This is expected to be within the detection capabilities of GRACE. With terrestrial absolute gravimetry, the gravity change due to the land uplift can be observed with an accuracy of ±10 to 20 nm/s2 for a 5-year period. Thus, the terrestrial insitu observations (ground-truth) may be used to validate and test the GRACE results.Since 2003, absolute gravity measurements have been performed in Fennoscandia at about 30 stations covering Norway, Sweden, Finland and Denmark. Four groups with FG5 absolute gravimeters (BKG, FGI, IfE, UMB) are engaged to survey the uplift network annually by a mutually controlled procedure. Nearly all absolute stations are colocated with permanent GPS stations. From the 2003 and 2004 comparisons between the instruments, an overall accuracy of ±30 nm/s2 is indicated for a single absolute gravimeter and a single station determination. This is in full agreement with the project goal.
|
|
