A 2-D Frequency-Domain Algorithm to Remove GRACE Stripe Noise

The gravity recovery and climate experiment (GRACE) sensors observe changes in the Earth’s mass distribution between water storage compartments, estimating the terrestrial water stage (TWS). Unfortunately, the estimation is affected by noise, characterized by primary north–south-oriented stripes. The noise impact is severe in tropical areas. Existing denoising algorithms remove the stripes, but the noise removal and signal preservation can be further improved. Thus, a new 2-D frequency-domain filtering algorithm is proposed, consisting of notch filter banks and a low-pass filter. Also, the relative sum absolute difference (RSAD) is proposed to evaluate noise removal and signal preservation effectiveness. The proposed algorithm removed stripe noise and preserved signal in simulated noisy GRACE Level-2 data. The denoised results were satisfactory qualitatively and quantitatively assessed by the RSAD. In addition, the proposed algorithm outperforms three existing denoising algorithms in noise removal and signal preservation.