A New 1-Hourly ERA5-Based Atmosphere De-Aliasing Product for GRACE, GRACE-FO, and Future Gravity Missions
Abstract
The current state-of-the-art of satellite gravity data processing makes use of de-aliasing products to reduce high-frequency mass anomalies. For example, the most recent official Atmosphere and Ocean De-aliasing products (AOD1B-RL06) are applied for the Gravity Recovery and Climate Experiment (GRACE) and GRACE-Follow On (GRACE-FO) missions. The temporal resolution of AOD1B-RL06 is 3 h, and spectrally, they are computed up to degree and order 180. In this study, we explore a refined, e.g., geometrically, physically, and numerically improved, mass integration approach that is important for computing the atmosphere part of these products. Besides, the newly available ERA5 climate data are used to produce a new set of non-tidal atmosphere de-aliasing product (HUST-ERA5) that is computed hourly up to degree and order 100, covering 2002 onwards. Despite an overall agreement with AOD1B-RL06 (correlation≥0.99), considerable discrepancies still exist between HUST-ERA5 and AOD1B-RL06. The possible reasons are therefore analyzed, and we find the input climate data, sampling rate and integration method may result in a product difference of ∼0.3, ∼0.15 and ∼0.05 millimeter geoid height, respectively. The total differences between HUST-ERA5 and AOD1B-RL06 can lead to a mean variation of ∼7.34 nm/s on the laser ranging interferometry (LRI) range-rate residuals, for example, during January 2019, which is already close to the LRI precision. This impact is invisible for the GRACE (-FO) gravity inversion because of the less accurate on-board KBR (K-band ranging) instrument, however, it will be non-negligible and should be considered when the LRI completely replaces the KBR in the future gravity missions.
- Publication:
-
Journal of Geophysical Research (Solid Earth)
- Pub Date:
- September 2021
- DOI:
- Bibcode:
- 2021JGRB..12621926Y
- Keywords:
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- GRACE;
- GRACE-FO;
- AOD;
- De-aliasing;
- ERA5;
- Gravity field