Hydromagnetic dynamo theory in geo- and astrophysics 1 1100-TDH1
1. History of theories describing the generation of the geomagnetic field.
2. The Earth's dynamo compared to the dynamo on other objects of the solar system (the Sun, Mercury, Venus, Jupiter's moon Io, Jupiter and Mars, the Moon in the past). Why is the Earth Dynamo still so effective?
3. Magnetohydrodynamics equations
a. Navier-Stokes equation with Lorentz force
b. Maxwell's equations
c. Derivation of the equation of the magnetic field induction
d. Helmholtz theorem of the frozen magnetic field.
e. Taylor-Proudman theorem
f. Basics of the theoretical description of turbulence, renormalization of the Navier-Stokes equations.
4. Mechanisms of magnetic field generation
a. Omega effect and alpha effect - mean field theory.
b. Dynamo type alpha-Omega and alpha^2
c. Magnetic instabilities - magnetorotational instability and instability of magnetic buoyancy in the context of the Solar Tachocline.
d. Tidal instability (source of the magnetic field on Io).
During the exercise classes, some introductory and supplementary problems will be solved on the above-mentioned aspects of the hydromagnetic dynamo, including the use of MATLAB and MATHEMATICA packages. The exercises will take place partly at the blackboard (solving simple examples), but mostly at the computer (programming with the use of the above-mentioned packages).
Assessment criteria
Students will be required to complete one task per semester to pass. I will present the topics of these tasks during the first lecture - there will be topics to choose from. Some will be descriptive, others more mathematical. In addition, passing an oral exam will be required.
Bibliography
The lecture will not be fully based on any particular book and its aim will be to present complex issues related to the hydromagnetic dynamo in an accessible form. Therefore, there is no single textbook, but the recommended literature includes (will be sent to students in electronic form):
[1] P. Roberts 1967, An introduction to magnetohydrodynamics, American Elsevier Pub. What.
[2] H.K. Moffatt and E. Dormy 2019, Self-exciting fluid dynamos, Cambridge University Press,
[3] K.A. Mizerski 2021, Foundations of Convection with density stratification, Springer
[4] IUGG, 2020, Geomagnetism, Aeronomy and Space Weather, Eds. M. Mandea, M. Korte, A. Yau, E. Petrovsky, Cambridge University Press.
Additional information
Additional information (registration calendar, class conductors, localization and schedules of classes), might be available in the USOSweb system: