Intrayear irregularities of the Earth’s rotation

Irregularities of the Earth’s rotation and the problem of the time scale instability

“…Earlier, the authors of [3][4][5] considered the possi bility of forecasting quasi periodic oscillations of the day duration in the mean frequency range; taking them into account is statistically significant and can be justified within intervals close to periods of corre sponding components. Structure expressions were written for the numerical simulation.…”

“…Here, C* is the axial moment of inertia with account taken of deformations of the "frozen" configuration of the Earth; ϕ is the angle of proper rotation; is the lunar-solar gravitational-tidal moments of force with primary frequencies [3][4][5]; ΔM SL ( , ) are terms of a higher order of smallness in the expansion of the lunar-solar gravitational-tidal moment of the spa tial variant of the given problem. The quantity of the variation of day duration l.o.d.…”

“…The quantity of the variation of day duration l.o.d. (ϕ, t) (length of the day changes) is defined by the following expression [1,[3][4][5]: Here 〈…〉 ϕ is the symbol of averaging within a diurnal time interval.…”

“…(3) The celestial mechanics model of tidal regular variations of the Earth's axial rotation velocity is described by a linear system of differential equations [3][4][5]:…”

“…Let us note that variations in the velocity of the Earth's axial rotation, the period and mean motion of the Moon, and the mean distance or the semimajor axis of the lunar orbit, including the principal inequalities in the lunar motion, are essen tially interrelated parameters [2][3][4][5][6].…”