| Abstrakt: |
Satellite measurements are essential for understanding Earth's complex system, yet they often lack a reliable a‐priori covariance matrix. This study presents a new methodology to enhance the reliability of satellite measurements by deriving experimental covariance matrices from the original observation. We focus on the accelerometer measurements (1A dataset) from the GRACE (Gravity Recovery and Climate Experiment) C satellite. Using autocorrelation analysis, we create a block‐diagonal covariance matrix for the 1A dataset. We then apply a low‐pass Gaussian filter that integrates this covariance matrix into the least squares estimation, resulting in a refined 1B dataset that minimizes spikes and spurious accelerations while preserving measurement error. Our variance analysis uncovers disturbances linked to geomagnetic storms and the satellite's transitions through Earth's shadow and terminator, with fluctuations notably peaking during the equinoxes. Plain Language Summary: We developed an effective method to generate covariance matrices directly from the raw accelerometer measurements of Gravity Recovery and Climate Experiment (GRACE) C (10 Hz $Hz$ sampling rate) that can be applied to any satellite measurements structured as time or data series. The result of this method is a weighted accelerometer 1B dataset, free of spurious spikes typically present in accelerometer measurements, while preserving error information through the inclusion of measurement variances and correlations. Our approach excels at detecting errors and preserving important signals. Notably, the accelerometer variances depend on latitude and local time, increase during equinoxes and geomagnetic storms, and are highest in the radial direction. Key Points: A new post‐processed 1B accelerometer dataset has been developed for GRACE C satelliteThe dataset variances exhibit significant dependence on equinoxes, terminator crossings, latitude, local time, and β' angleThese variances show strong signals associated with geomagnetic storms [ABSTRACT FROM AUTHOR] |
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