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Andrew Jackson

Self Introduction

I'm very happy to have had the opportunity to take up the generous offer of Prof. Utada to come and visit ERI. I am professor of geophysics at the Swiss Federal Institute of Technology in Zurich Switzerland. I am primarily interested in the physics of the Earth's core, in particular the mechanism by which the magnetic field is created and sustained over Earth's history. We approach this problem from both an observational and computational perspective.

One of the exciting upcoming events of the next years will be the launch of the European Space Agency's Swarm mission to measure the Earth's magnetic field from space with unprecedented accuracy. The mission uses 3 satellites with some concepts of gradiometry in its design. Our group at ETH plans to try to perform space-based induction studies, to retrieve upper mantle electrical conductivity. Amongst other things, Prof Utada's network of observatories in the Pacific will play a role in this effort. I greatly look forward to the opportunity of learning about the research endevours of ERI scientists.

Research Report

I visited ERI as a guest of Utada-san. During the visit I interacted with Shimizu-san on the subject of propagation of torsional oscillations in the core. We also discussed his most recent results for the electrical conductivity of the mantle derived from MT data and voltages on cables in the Pacific. I took the opportunity to work on a problem concerned with finding properties of the magnetic field in the core when the quasi-geostrophic assumption is adopted. This problem is an unusual inverse problem, in that the variables that are sought must satisfy the Cauchy-Schwarz inequality. One requires a parametrisation that implicitly honours that inequality. Fortunately a solution was forthcoming, and allows further progress on finding properties of the interior core field.

George Hellfrich, also visiting professor, and I discussed his recent results suggesting stratification of the outer reaches of the core. I took the opportunity to write a News and Views oppinion piece for Nature, attached. I would like to thank the International Office for their fine handing of the logistics, and Utada-san for acting as a genial host.