Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Fast Quasi-Geostrophic Magneto-Coriolis Modes in the Earth's core   Fast changes of Earth's magnetic field could be explained by inviscid and
diffusion-less quasi-geostrophic (QG) Magneto-Coriolis modes. We present a
hybrid QG model with columnar flows and three-dimensional magnetic fields and
find modes with periods of a few years at parameters relevant to Earth's core.
For the simple poloidal magnetic field that we consider here they show a
localization of kinetic and magnetic energy in the equatorial region. This
concentration of energy near the equator and the high frequency make them a
plausible mechanism to explain similar features observed in recent geomagnetic
field observations. Our model potentially opens a way to probe the otherwise
inaccessible magnetic field structure in the Earth's outer core.

33
The categories of this paper are: plasm-ph
30
The categories of this paper are: q-alg
5
The categories of this paper are: gr-qc
20
The categories of this paper are: acc-phys
26
The categories of this paper are: bayes-an
22
The categories of this paper are: chao-dyn
9
The categories of this paper are: nlin
2
The categories of this paper are: math
17
The categories of this paper are: q-fin
18
The categories of this paper are: econ
24
The categories of this paper are: dg-ga
37
The categories of this paper are: supr-con
13
The categories of this paper are: quant-ph
31
The categories of this paper are: ao-sci
25
The categories of this paper are: patt-sol
36
The categories of this paper are: cmp-lg