Beschreibung:
<jats:p>Abstract. Over a decade ago the semidiurnal lunar M2 ocean tide was identified in CHAMP
satellite magnetometer data. Since then and especially since the launch of
the satellite mission Swarm, electromagnetic tidal observations from
satellites are increasingly used to infer electric properties of the upper
mantle. In most of these inversions, ocean tidal models are used to generate
oceanic tidal electromagnetic signals via electromagnetic induction. The
modeled signals are subsequently compared to the satellite observations.
During the inversion, since the tidal models are considered error free,
discrepancies between forward models and observations are projected only onto
the induction part of the modeling, e.g., Earth's conductivity distribution.
Our study analyzes uncertainties in oceanic tidal models from an
electromagnetic point of view. Velocities from hydrodynamic and assimilative
tidal models are converted into tidal electromagnetic signals and compared.
Respective uncertainties are estimated. The studies main goal is to provide
errors for electromagnetic inversion studies. At satellite height, the
differences between the hydrodynamic tidal models are found to reach up to
2 nT, i.e., over 100 % of the local M2 signal. Assimilative tidal models
show smaller differences of up to 0.1 nT, which in some locations still
corresponds to over 30 % of the M2 signal.
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