1 / 25

DynaQlim project and the GIA modelling

DynaQlim project and the GIA modelling. Markku Poutanen Finnish Geodetic Institute. Glacial Isostatic Adjustment. Land uplift is just one of the consequences of the Glacial Isostatic Adjustment, GIA

maisie
Download Presentation

DynaQlim project and the GIA modelling

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. DynaQlim project and the GIA modelling Markku Poutanen Finnish Geodetic Institute

  2. Glacial Isostatic Adjustment • Land uplift is just one of the consequences of the Glacial Isostatic Adjustment, GIA • GIA-related phenomena originate to the large-scale mass transportation; Waxing and waning of the Northern hemisphere glaciers in about 100 000 year cycles cause up to 135 m of global sea level rise and fall. This corresponds about 5×1019 kg of mass • The mass transportation causes cyclic variation on the surface load resulting in the viscoelastic mantle flow and elastic effects on the lithosphere • No single technique or observing network will give enough information on all aspects and consequences of GIA

  3. Glacial Isostatic Adjustment • GIA with its unique temporal signatures is one of the great opportunities in geosciences to retrieve information about Earth processes. • GIA contains information about recent climate forcing, being dependent on the geologically recent on- and off-loading of ice sheets. • GIA gives a unique chance to study the dynamics and rheology of the lithosphere and asthenosphere with an increasingly detailed modelling • GIA is of fundamental importance in geodesy, since reference frames, physical heights, Earth rotation and polar motion are influenced by it.

  4. Other signals • The GIA signal is contaminated by several other spatially and temporally varying mass changes and crustal deformation. These include seismic deformation, mantle convection, plate tectonics and other tectonic phenomena • Sea level change is an example of a phenomenon which is related to GIA but mixed with other signals. The observed sea level change relative to a fixed benchmark on the ground contains components of • GIA related crustal vertical motion • other crustal motions (tectonic, anthropogenic, ...) • eustatic rise of the sea level • seawater thermal expansion • changes in semi-permanent sea surface topography • geoid changes

  5. Growth and decay of a glacier

  6. Mitrovica et al., Nature 2001 Scenario if Greenland glacier is melting

  7. DynaQlimUpper Mantle Dynamics and Quaternary Climate in Cratonic AreasA regional co-ordination committee of the International Lithosphere Program (ILP) Markku Poutanen and the DynaQlim Group* * Søren Gregersen, Sören Haubrock, Erik Ivins, Matt King, Volker Klemann, Ilmo Kukkonen, Juha-Pekka Lunkka, Christophe Pascal, Hans-Georg Scherneck, Bert Vermeersen

  8. Objectives of DynaQlim • to collectexisting relevant geo-data for improving geophysical models, • to improve kinematic 3-D models,and in general, understand better the dynamics of the Earth's crust, • to better understand the relations between the upper mantle dynamics, mantle composition, physical properties, temperature and rheology, • to studythe effect of Quaternary climate, glaciation cycles and ice thickness on contemporary climate, rebound rate,… • to study the Quaternary climate variations and Weichselian (Laurentian and other) glaciations,

  9. Objectives of DynaQlim • to study the response of the gravity field with different ice loads and to understand the secular change of gravity in the rebound area and especially in its margin areas, • to apply the results in the polar regions, like the glaciation history in Antarctica and Greenland and the Holocene rebound history in deglaciated areas, • to offer reliable data for other disciplines in geoscience and for studies of the global change, sea level rise and climate variation

  10. Collaborating disciplines 7) IT management and outreach 1) Geodesy, geodynamics, ocean dynamics 6) Properties of lithosphere 2) GIA, gravity, kinematics 3) Dynamic ice sheets, glaciology 5) Neotectonics, seismotectonics 4) Quaternary palaeo- environments, climate

  11. Activities 2009-2010 UnderstandingGlacial Isostatic AdjustmentGGOS/DynaQlim workshop, Espoo Finland 6/2009 Sessions in EGU General Assembly 2009, 2010 Journal of Geodynamics Special issue (2010) Physics and Chemistry of the Earth Special issue under preparation Long introductory article in New Frontiers in Integrated Solid Earth Sciences (Eds. Cloetingh, S and Negendank, J.). (Springer book) • Workshop objectives • review the current state of the science in modeling glacial isostatic adjustment, • review the use of geodetic measurements to both constrain and to test GIA models, • identify obstacles to improving GIA models, and • identify the improvements to the global geodetic observing system that are required to advance our understanding of glacial isostatic adjustment.

  12. …but we’re not going to re-invent a wheel (In the history of mankind it was a great innovation to use a 3-corner wheel instead of a 4-corner wheel because a 3-corner wheel causes one bump less in every revolution…)

  13. Geodetic Observing systems and multi-technique sites • To observevariousaspects of GIA weneedseveraltechniques; in geodesyweobserve 3D-motions, gravity, EOP, sealevel, … • Thisimplies: GNSS, SLR, VLBI, AG, SCG, levelling, relative gravimetry, altimetry, InSAR, … • Geodetic Observing Systems: GGOS, ECGN, NGOS, … • Special projects (BIFROST, COST ES0701, DynaQlim…) + terrestrial levelling, AG, SCG, rel.g, tide gauges, …

  14. Global Reference Frames SLR VLBI GNSS Motivation for multi-technique sites BGI Geodynamics Postglacial rebound Earth structure Gravity changes Vertical datums Local coordinates

  15. Observing techniques IAG SERVICE (IVS) IAG SERVICE (ILRS) IAG SERVICE (IGS), EPN, NKG, more IAG SERVICE (IDS) UELN, Nordic PSML AG plan + archive (developing) GGP (IAG PROJECT ) Manysources, partlyavailable Meta-databases, data archives, partlyavailable

  16. Postglacial rebound Maps of vertical motion have traditionally been based on long time series of tide gauges and repeated precise levellings over several decades. Today we can observe 3-D motions with GNSS Courtesy Martin Lidberg / BIFROST

  17. Data, errors and noise • Time series are noisy and may contain various errors or biases • Changes in trend (annual, decadal, random) • Outliers and environmental errors Nordman, 2007 Sea level and prediction Gravity differences Mäkinen, 2004 Kahma, 2008

  18. Uplift rate vs. distance We get different values when using different techniques; Blue = GPS time series, Green = tide gauge data, Red = model

  19. NKG2005LU uplift model

  20. Differences between models Comparison of the Nordic land uplift model NKG2005LU with observed velocities [mm/y] in Finland. Vertical velocities are estimated from the three precise levelling. Open small circles represent levelling bench marks in bedrock. The thick grey isobases come from the NKG2005LU and the thin black isobases from the three precise levellings in Finland.

  21. Societal needs: Renewal of national height systems 1892-1910 1935-1975 1978-2006 N00 N60 N2000 Due to land uplift, the renewal of a national height system is needed approximately twice / century; precise levelling is a labourous task…

  22. Common Nordic adjustment Created as a Nordic co-operation ”EVRS compatible”; but national realisations Saaranen 2006 Land uplift is the dominating factor in new height readings Mäkinen 2005

  23. Global change, glaciers:Greenland mass change Dietrich 2008 -193 +/- 22 Gt/a Mass change based on GRACE satellite data [mm water per year] If the melting rate remains constant, melting will take more than 10000 years Associated with crustal deformation; uplift/subsidence by GNSS

  24. Local measurements: Uplift induced stress?

  25. Summary • GIA is very complicated in the viewpoint of precise observations and reference frames • No single observing technique is sufficient • Geodetic observing systems (GGOS, ECGN, NGOS, …) offer (or will/should offer) multi-technique data/sites in a coordinated way • We need also regional and local dense networks • Repeated gravity observations are essential • Many GIA-related phenomena are global but many consequences are local and may have also serious societal aspects (sea level rise, earth quakes, …) or which are laborious and expensive (new height systems) • Sub-mm accuracy achievable in ten years with GPS + levelling is needed for proper height control and to maintain vertical references

More Related