Earth orientation and its excitations by atmosphere, oceans, and geomagnetic jerks
2015
In addition to torques exerted by the Moon, Sun, and planets, changes of the
Earth orientation parameters (EOP) are known to be caused also by excitations
by the atmosphere and oceans. Recently appeared studies, hinting that
geomagnetic jerks (GMJ, rapid changes of geomagnetic field) might be
associated with sudden changes of phase and amplitude of EOP (Holme and de
Viron 2005, 2013, Gibert and Le Mouёl 2008, Malkin 2013). We (Ron et al.
2015) used additional excitations applied at the epochs of GMJ to derive its
influence on motion of the spin axis of the Earth in space
(precession-nutation). We demonstrated that this effect, if combined with the
influence of the atmosphere and oceans, improves substantially the agreement
with celestial pole offsets observed by Very Long-Baseline Interferometry.
Here we concentrate our efforts to study possible influence of GMJ on
temporal changes of all five Earth orientation parameters defining the
complete Earth orientation in space. Numerical integration of Brzezinski's
broad-band Liouville equations (Brzezinski 1994) with atmospheric and oceanic
excitations, combined with expected GMJ effects, is used to derive EOP and
compare them with their observed values. We demonstrate that the agreement
between all five Earth orientation parameters integrated by this method and
those observed by space geodesy is improved substantially if the influence of
additional excitations at GMJ epochs is added to excitations by the
atmosphere and oceans.
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