Journal of Conference Abstracts

Inner Core of the Earth: Process of Latitudes Change and its Relation to Geodynamo Problem

Boris Levin (levin@rfbr.ru) & Jurij Avsjuk (levin@rfbr.ru)

P.P. Shirshov Institute of Oceanology, RAS, Nakhimovsky prosp., 36, Moscow, 117851, Russia

There are facts to which geophysics pay little attention, also their consideration is important in respect to geodynamics problems. Let's start with accurate description of the Earth's orbit movement.

The center of mass of Earth-Moon system (barycenter) moves around the Sun with a period of 365 days. The ecliptic plane - is a plane of the barycenter orbital movement, and not the Earth alone. The Sun's attraction is dynamically balanced within the barycenter. The Earth rotates around the barycenter with a monthly periodicity. The theory of the Moon's movement that describes all the perturbations is at the same time a theory of the Earth's movement around the barycenter. The perturbations modulus of the Earth's orbital movement is 81 times less than the Moon's (what equals to the ratio of Earth mass to the mass of the Moon). The periodicities of the perturbations of the monthly movement are characterized by the values 412-437 days (for the series with "one point per month" temporal resolution) and 6 years (with "one point per year" sampling frequency).

Based on the study of latitudes change C.Chandler in 1891 empirically established the periodicity of one year and 410-440 days (with 0.1 year sampling frequency) and 6-7 years periodicity (with annual sampling frequency). The similarity of the Earth's orbital movement and latitudes change cycles remained out of the geophysics discussions. Only the model of free nutation has been considered what gave birth to many questions that still have no answers.

In 1936 Inge Lemann found the existence of the inner core (IC) suspended in the surrounding melt - the outer core (OC). There is a natural question: if the (IC) is not rigidly connected with the (OC) and if the Sun's attraction is dynamically balanced within the barycenter and not within the Earth's center where the (IC) is located, will in this case the (IC) remain in a permanent position, or will it move with the forcing periodicity?

The founding of C.Chandler provides grounds for the answer: the (IC) is drifting in the surrounding (OC). The founding of I.Lemann explains the mechanism of the rotation axis shifts within the Earth's body. It is clear that these movements lead to the formation of the (IC)-(OC) boundary layer, which is in nowadays confirmed by analyses of the anisotropy of seismic waves propagating through the core (Poupinet, 1983; Jealoz et al.,1988; Romanowicz et al., 1996). The report deals with detailed discussion of the consequences of the induced (IC) movements and their relation to the problem of geodynamo.