SIOG231
is jointly taught by
Steven
Constable (sconstable@ucsd.edu), Munk 326,
and
Cathy
Constable (cconstable@ucsd.edu), Munk 329,
Meets Winter
2024 Tues/Thurs 9:30-10:50 am
SIOG 231, Geomagnetism and
Electromagnetism, will cover the theory of geomagnetism and electromagnetic
induction, instrumentation, forward and inverse modeling of data, properties of
Earth materials, and applications.
Earth's magnetic field shields life, and even the atmosphere itself,
from the solar wind, and is used by organisms from bacteria to birds for
navigation (humans too). Observations of
Earth's internal and external magnetic fields are used to understand how the
core geodynamo works, and to image the electrical
conductivity structure of the crust and mantle by means of the magnetotelluric method.
The magnetotelluric method has become an
important tool, often used alongside seismic methods, to study a variety of
geological processes, and is used extensively on land and at sea both
commercially and academically.
Topics to be covered are listed
below. Students will be expected to complete homework assignments designed to
develop hands-on skills in manipulating geomagnetic and electromagnetic
data. Grading will be based on active
class participation, homework, and a final project.
Prerequisite: graduate standing or
consent of instructors.
Lecture 1- 01/09/2024
Topics: Introduction, motivation, history, overview of the
applications
Reading: Chapter 1, notes, pages 1-15
Slides for Lecture 1 (pdf), or Keynote
Lecture 2- 01/11/2024
Topics: Classical Electrodynamics
Reading: Chapter 2 –
Slides for Lecture 2 (pdf), or Keynote
Homework 1 - due 1/18/2024
Lecture 3- 01/16/2024
Topics: Lorentz Force, Diffusion Equations,
Electromagnetic Sounding
Reading: Chapter 3 notes
Slides for Lecture 3(pdf), or Keynote
Lecture 4- 01/18/2024
Topics: Instrumentation
Reading: Chapter 4 notes
Slides for Lecture 4(pdf), or Keynote -updated 1/22/2024
Homework 2 - due
1/25/2024
Lecture 5- 01/23/2024
Topics: Gauss’ Theory and the Main
Geomagnetic Field
Reading: Chapter 5 notes
Slides for Lecture 5(pdf), or Keynote – updated 1/23/2024
Lecture 6- 01/25/2024
Topics: Spherical harmonic representation, internal/external
separation, upward and downward continuation
Slides for Lecture 6(pdf) or Keynote – updated 1/25/2024
Lecture 7- 01/30/2024
Topics: Secular Variation and Geomagnetic Power
Spectra
Slides for Lecture 7(pdf) – updated 1/30/2024
Gufm1 animation
GGF100k animation
Link to EOS article on the World Magnetic Model
Lecture 8- 02/01/2024
Topics: Earth’s external geomagnetic and electromagnetic
environment.
Reading: Chapter 8 notes
Slides for Lecture 8(pdf) or Keynote – updated 2/1/2024
Homework 3 - due
2/13/2024
Data sets for homework:
CHAOS average field model chaos7_9_av_lm
MAGSAT pass331.dat
Link to Grand Spectrum paper
Using magnetic fields to predict tsunami wave height
Lecture 9- 02/06/2024
Topics: Geomagnetic
depth sounding + Fitting data: Least squares, errors, parameter estimation.
Reading: Chapter 9 notes
Slides for Lecture 9(pdf) or Keynote – updated 2/5/2024
Lecture 10- 02/08/2024
Topics: Main
field modeling, regularization.
Reading: Chapter 10 notes
Slides for Lecture 10 (pdf) or Keynote updated 2/11/2024
Lecture 11- 02/13/2024
Topics: Lithospheric
fields, magnetic remanence, Runcorn’s theorem.
Reading: Chapter 11 notes
Slides for Lecture 11 (pdf) or Keynote – updated 2/12/2024
Lecture 12- 02/15/2024
Topics: The one-dimensional Earth - Forward modeling
using finite differences and finite elements.
Reading:
Chapter 15 notes
Slides for Lecture 12 (pdf) or Keynote - updated 2/15/2024 - fixed a few typos
Homework 4 – due 02/27/2024 - updated 2/14/2024
Lecture 13- 02/20/2024
Topics: The Magnetotelluric
Method.
Reading:
Chapter 14 notes
Slides for Lecture 13(pdf) or Keynote updated 2/20/2024
Lecture 14- 02/22/2024
Topics: The Geodynamo: Toroidal and poloidal fields,
Magnetohydrodynamics in Earth’s Core I
Reading: Chapter
12-13 notes
Slides for Lecture 14 (pdf) or Keynote - updated 2/22/2024
Lecture 15- 02/27/2024
Topics: Magnetohydrodynamics
in Earth’s Core II
Reading: Chapter
12-13 notes
Slides for Lecture 15 (pdf) or Keynote
Lecture 16- 02/29/2024
Topics: Modeling in Higher Dimensions
Reading: Chapter 16a - The Two-Dimensional MT Forward Problems, notes from Bob
Parker
Slides for Lecture 16 (pdf) or Keynote
Lecture 17- 03/05/2024
Topics: Regularized Inversion
Reading: Chapter 17
Slides for Lecture 17 (pdf) or Keynote
Lecture 18- 03/07/2024
Topics: Electrical conductivity of rocks, minerals,
and melts. The crust, mantle, and core.
Reading: Chapter 18 – Electrical conductivity of Rocks
Slides for Lecture 18 (pdf) or Keynote
______________________
Lecture 19 - 03/12/2024
Topics: The Solar Dynamo
Reading: review paper by Charbonneau
(2014) doi: 10.1146/annurev-astro-081913-040012
Slides for Lecture 19 (pdf) or Keynote
Homework 5 - due 3/21/2024
Lecture 20 - 03/14/2024
Topic: From the Sun to Earth's core: The EM response of the sunspot
cycle and the conductivity of the lowermost mantle
Slides for Lecture 20 (pdf) or Keynote
Background Stuff: A few
resources for getting started if you forgot or never learned EM as an
undergraduate.
Basic physics of magnetic fields, Chapters 5-7, of Introduction to Electrodynamics, David
J. Griffiths,
4th Edition, Cambridge University Press, 2017.
Div and Curl Grant
Sanderson on his Youtube channel 3blue1brown, which has some useful
visualization and intuition about divs and curls.
More things are covered at an elementary level in Khan Academy
e.g., Laplacian intuition, …. Harmonic functions
Supplementary
References, Geomagnetism:
Foundations of Geomagnetism
George Backus, Robert Parker, Catherine Constable
Cambridge University Press, New York 1996
Introduction to Electrodynamics, David J. Griffiths,
4th Edition, Cambridge University Press, 2017.
Treatise on Geophysics,
Volume 5, Geomagnetism
Volume Editor: M. Kono. Editor-in-Chief: G. Schubert
Elsevier, Amsterdam, 2015, 2nd
Edition.
[available online from UCSD in electronic
format]
Technical summaries of many
current topics in geomagnetic and electromagnetic research.
Treatise on Geophysics,
Volume 8, Core Dynamics
Volume Editor: P. Olson.
Editor-in-Chief: G. Schubert
Elsevier, Amsterdam, 2015, 2nd
Edition.
[available online from UCSD in electronic
format]
Technical summaries of many
current topics in core dynamics.
Space Science reviews volume
on Planetary Magnetism at http://link.springer.com/journal/11214/152/1/page/1
And Terrestrial Magnetism http://link.springer.com/journal/11214/155/1/page/1
Earth’s
Electromagnetic Environment Surv Geophys
DOI 10.1007/s10712-015-9351-1
Potential Theory in Gravity and Magnetic Applications
Richard J. Blakely
Cambridge University Press, New York 1995
Available online
Another look at potential theory, specifically in the context of gravity and geomagnetism.