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The Gravity Recovery and Climate Experiment (GRACE) gravitational models suffer from a dominant systematic error, usually referred to as "longitudinal stripes." These stripes contaminate useful geophysical signals and limit the spectrum of geoscience applications that can be benefited from GRACE and GRACE-Follow On. Analyses of the spatiotemporal structure of latitudinal stripe profiles show consistent spectral characteristics throughout three years of monthly solutions. Using an elegant combination of GRACE sampling characteristics and advanced moire theory, we show that the GRACE stripes are sub-Nyquist (pseudo-moire) artifacts arising from the oversampling of the Earth's low-frequency static disturbing potential (geoid) along the parallels. The low-frequency geoid modulates the total sampled gravitational signal with a frequency near m/n f(s), where f(s) is the sampling frequency of the GRACE ground track "bundles" along the parallels of latitude, and m and n are mutually prime integers, with 2m <= n.

Plain Language Summary The Gravity Recovery and Climate Experiment (GRACE) mission allowed the monitoring of the Earth's static and dynamic gravity field. Although GRACE has been subject to an extensive number of studies, GRACE-based gravity field models display strong disturbing systematic noise in the form of "stripes" extending longitudinally and around the globe, contaminating useful geophysical signals. Their origin has not been explained since the launch of GRACE in 2002. Thorough analyses of the spatiotemporal structure of GRACE stripes reveal that their location is nonstationary but with consistent spectral characteristics over monthly and long-term gravity models. In this contribution, we quantify the GRACE sampling characteristics and we use them to prove that the stripes are sub-Nyquist (pseudo-moire) artifacts. We prove that the stripes are the result of oversampling the low frequency geoid along the east-west (latitudinal) direction. We generate synthetic stripes using moire theory, and by means of rigorous spectral analysis, we show that their spectral and spatial characteristics are very similar to the observed ones.