Multidisciplinary studies of Deep Earth:From Geodynamo to Geodesy

1. Multidisciplinary studies of Deep Earth:From Geodynamo to Geodesy Weijia Kuang Joint Center for Earth Systems Technology, UMBC Space Geodesy Branch, Code 926, NASA Goddard Space Flight Center Introduction 1. Mass redistribution in the core and time-variable gravity field 2. Pressure variation at CMB and mantle deformation 3. Prediction of geomagnetic secular variation

2. Serving our society !? Introduction What can numerical dynamo modeling tell us about the Earth? What can surface geophysical observations tell us about core dynamics?

3. Introduction Core interacts with Mantle on different time scales ! Core convection is controlled by mantle thermodynamic processes on very long time scales (~ 108 years) Mantle reacts to the forces from core on short time scales (~ 10 years)

4. Introduction What surface observations can tell us about the core dynamics? • Geomagnetic field observations:

5. Introduction What surface observations can tell us about the core dynamics? • Geomagnetic field observations: • Earth’s rotation variation

6. Introduction What surface observations can tell us about the core dynamics? Geomagnetic + LOD

7. Any more observations can serve our purposes?

8. Mass Redistribution in the Core and Gravity Field The core is in convection: two types of mass redistribution • Density anomalies driving convection

9. Mass Redistribution in the Core and Gravity Field

10. Mass Redistribution in the Core and Gravity Field • Mass redistribution around ICB

11. At CMB, Mass Redistribution in the Core and Gravity Field

12. Mass Redistribution in the Core and Gravity Field

13. Pressure Loading at CMB and Mantle Deformation The core is exerting a time-varying, non hydrostatic pressure at the CMB.

14. p  10 mb

15. Pressure Loading at CMB and Mantle Deformation

16. Prediction of Geomagnetic Field Secular Variation Promising in applying numerical dynamo modeling to predict geomagnetic field secular variation

18. Conclusion We should/could pursue the path of applying numerical modeling to surface observations • Using observational results to guide our numerical modeling, and to understand fundamental physics • Initiating multi-disciplinary studies on Earth’s deep interior • Being prepared for, and helping shape the direction of technology new technology advancement • Being prepared for, and helping shape the direction of technology new technology advancement

19. Introduction What surface observations can tell us about the core dynamics? • Geomagnetic field observations:

20. Inertia dominates drag Drag dominatesinertia