Treatment of temporal aliasing effects in the context of next generation satellite gravimetry missions

Abstract

Temporal aliasing effects have a large impact on the gravity field accuracy of current gravimetry missions and are also expected to dominate the error budget of Next Generation Gravimetry Missions (NGGMs). This paper focuses on aspects concerning their treatment in the context of Low‐Low Satellite‐to‐Satellite Tracking NGGMs. Closed‐loop full‐scale simulations are performed for a two‐pair Bender‐type Satellite Formation Flight (SFF), by taking into account error models of new generation instrument technology. The enhanced spatial sampling and error isotropy enable a further reduction of temporal aliasing errors from the processing perspective. A parameterization technique is adopted where the functional model is augmented by low‐resolution gravity field solutions coestimated at short time intervals, while the remaining higher‐resolution gravity field solution is estimated at a longer time interval. Fine‐tuning the parameterization choices leads to significant reduction of the temporal aliasing effects. The investigations reveal that the parameterization technique in case of a Bender‐type SFF can successfully mitigate aliasing effects caused by undersampling of high‐frequency atmospheric and oceanic signals, since their most significant variations can be captured by daily coestimated solutions. This amounts to a “self‐dealiasing” method that differs significantly from the classical dealiasing approach used nowadays for Gravity Recovery and Climate Experiment processing, enabling NGGMs to retrieve the complete spectrum of Earth's nontidal geophysical processes, including, for the first time, high‐frequency atmospheric and oceanic variations.

Impact of a novel hybrid accelerometer on satellite gravimetry performance

“…In order to maximize its potential, the application of de-aliasing techniques, especially for non-tidal AO signals and the tidal component of the gravity field, shall be a decisive factor. This is a reasonable demand for the upcoming decades, as first results by Daras and Pail (2017) as well as Hauk and Pail (2018) have shown. The results of this study clearly encourage to further improve, in parallel to the processing strategies, also the performance of the key instruments, particularly the accelerometers.…”

“…However, it is reasonable to assume that a reduction of the temporal aliasing to a sufficiently low level may amplify the accelerometer's impact. We therefore apply the Wiese parametrization (Wiese et al, 2011;Daras and Pail, 2017) where low-resolution gravity fields for shorter time periods are estimated alongside the full solution, ultimately leading to an improvement of the latter. For this study, the best results could be obtained by co-estimating daily gravity fields up to degree and order 15.…”

Combination Analysis of Future Polar-Type Gravity Mission and GRACE Follow-On

“…The standard deviations (SD) of major onboard sensors' noises, listed in Table 3, are based on their performances in real GRACE data. As shown, 1-cm SD is selected for orbit positions [31][32][33]. With regard to the range-rate data, we add noise with SD of 0.2 µm/s to KBR measurements in GFO and FPG [18,45], while with SD of 10 nm/s to LRI measurements in GFO [18].…”

“…To mitigate the troublesome temporal aliasing effects, post-processing filtering techniques are generally applied as a standard procedure [28][29][30]. However, the fundamental solution should be based on the enhanced signal sampling and gravity field modelling strategy [31][32][33][34]. One of the most straightforward and efficient ways is to increase the number of satellites in space for denser sampling of gravity signals.…”

An Optimized Short‐Arc Approach: Methodology and Application to Develop Refined Time Series of Tongji‐Grace2018 GRACE Monthly Solutions

“…The improved data processing algorithms generally focus on refinements of background force models, GRACE Level‐1b data, gravity field recovery methodologies and noise modeling. Imperfectness of the background force models (especially ocean tide and dealiasing models; Daras & Pail, ;Zenner et al, ) will inevitably cause temporal aliasing, which is one of the reasons for the north‐south stripes (Loomis et al, ; Wiese et al, ). The enhanced ocean tide modeling (Mayer‐Gürr et al, ) and nontidal dealiasing strategy (Flechtner & Dobslaw, ) were demonstrated to reduce the impact of temporal aliasing on gravity field estimates to some extent.…”