Thu Aug 14, F. Flechtner
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Pfaffenzeller, Nikolas, Pail, Roland, and Gruber, Thomas, 2025. Impact of tone errors in future satellite gravimetry missions. Advances in Space Research, 75(10):6961–6980, doi:10.1016/j.asr.2025.02.059.
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@ARTICLE{2025AdSpR..75.6961P,
author = {{Pfaffenzeller}, Nikolas and {Pail}, Roland and {Gruber}, Thomas},
title = "{Impact of tone errors in future satellite gravimetry missions}",
journal = {Advances in Space Research},
keywords = {Satellite gravity, Satellite geodesy, Tone errors, Numerical simulations, Future gravity mission, Gravity field processing},
year = 2025,
month = may,
volume = {75},
number = {10},
pages = {6961-6980},
abstract = "{One of the main limiting factors to observe variations of the very low
degrees and orders of the spherical harmonic (SH) spectrum of
the Earth's gravity field with satellite gravimetry missions
like GRACE and GRACE-FO are the so-called tone errors. They are
deterministic errors occurring periodically at the orbital
frequency of the spacecraft (one cycle-per-revolution, 1 CPR)
and its multiples. Tone errors are generated by external
perturbations acting on the satellite at the spacecraft
environment and by spacecraft-internal processes. In this study,
we investigate the impact of tone errors on the resulting
gravity field model and their mitigation by numerical
simulations for selected mission concepts. We start with a
GRACE/GRACE-FO-like single polar pair mission concept and extend
the simulations to a so-called Bender double pair constellation
by adding an inclined (70{\textdegree}) satellite pair. Within
our gravity-field simulation approach, we consider realistic
instrument noise assumptions for the accelerometers and the
inter-satellite ranging instrument, leading to instrument-only
simulation scenarios. Tone error contributions are modeled at
so-called orbital harmonics at 1, 2, and 3 CPR and incorporated
into the instrumental noise time series. Three selected sets of
low, moderate and large tone amplitudes and the occurrence of a
single tone amplitude on either 1, 2, or 3 CPR are considered to
analyze the effects on gravity field retrieval. Simulation
results show, that for instrument-only scenarios, tone errors
significantly affect single polar pair solutions over the
complete SH spectrum by amplifying resonance orders, whereas
double pair solutions are less affected. Since the tone
amplitudes and occurrences are known, the applied stochastic
modeling based on the instrumental behavior is extended by
additional notch filters to mitigate the impact of tone errors.
This approach has been selected to identify its performance and
applicability for gravity field determination. Applying the
adapted stochastic model, we can conclude that for both
satellite constellations, the erroneous effect of tone errors in
the higher SH spectrum can be mitigated at the cost of increased
errors in the low degrees. The behavior, as seen in the
instrument-only scenarios, cannot be confirmed in additional,
more realistic simulations, including temporal gravity field
contributions, called full-noise scenarios. Temporal gravity
field signals are, in general, larger than the erroneous signal
caused by tone errors. The under-sampling of high-frequency mass
signals from atmosphere, ocean and ocean tides, causing temporal
aliasing, dominates the gravity field solution errors for single
and double pair constellations and is up to one order of
magnitude larger than the tone errors impact considering low and
moderate tone amplitudes. Only with large tone amplitudes the
tone error effect exceeds temporal aliasing in the case of a
single polar pair. In the presence of temporal aliasing applying
the adapted stochastic modeling is disadvantageous since the
down-weighting of specific frequencies via notch filters also
affects the temporal gravity field solutions, in particular the
single polar pair. Other suitable mitigation approaches to be
applied for real data processing are identified as possible
options.}",
doi = {10.1016/j.asr.2025.02.059},
adsurl = {https://ui.adsabs.harvard.edu/abs/2025AdSpR..75.6961P},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
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