The Magnetic Field Induced by the Bodily Tide in the Core of the Earth

Abstract

The motion in the liquid core of the earth due to the bodily tide can induce a periodic magnetic field having the frequency σ of the tide as well as multiple frequencies, including a steady term. The coupling coefficient for the steady term between the convectively inducing and induced fields is estimated to be of the order of σH ²/λ, where H denotes the height of the equilibrium tide, and λ = 1/4πκ, κ denoting the electrical conductivity of the core. With σ = 1.4 × 10^-4 sec^-1, H = 20 cm, and κ = 3 × 10^-6 emu, the coupling coefficient comes out only of the order of 10^-6, as against unity in the case of the dynamo theory.

• dynamo theory
• coupling coefficient