Status of AOD1B RL07

Abstract

<p>The Atmosphere and Ocean non-tidal De-aliasing Level-1B (AOD1B) product is widely used in satellite gravimetry to correct for transient effects of atmosphere-ocean mass variability that would otherwise alias into monthly-mean global gravity fields. The most recent release is based on the global ERA5 reanalysis and ECMWF operational data together with simulations from the general ocean circulation model MPIOM consistently forced with fields of the same atmospheric data-set.</p> <p>The talk focusses on the current status of the new release RL07. We present the changes made for RL07 with respect to the previous release RL06, the current status of the processing as well as the ongoing work in terms of consistency and uncertainty assessment.</p>

Non‐Tidal Background Modeling for Satellite Gravimetry Based on Operational ECWMF and ERA5 Reanalysis Data: AOD1B RL07

“…AOD1B RL07 is available at GFZs ISDC and published under Shihora, Balidakis, et al. (2022). Going forward, two further points will need to be addressed: (a) AOD1B is not only required to accurately represent the high‐frequency mass variations but also needs to exhibit a temporal stability over long time‐scales from years to decades to allow for a reliable signal separation of atmospheric mass change from the underlying terrestrial water cycle signals.…”

“…We also allow for the far‐field attraction effects of atmospheric pressure variability on ocean dynamics as detailed in Shihora, Sulzbach, et al. (2022).…”

“…The most significant differences, however, are found in the southern ocean in the region of the ACC. Here, model changes in MPIOM between v74 and RL06 such as the feedback from SAL as well as the inclusion of cavities under the Antarctic ice‐shelves have a rather strong effect (Schindelegger et al., 2021; Shihora, Sulzbach, et al., 2022).…”

Non‐Tidal Ocean Loading Signals of the North and Baltic Sea From Terrestrial Gravimetry, GNSS, and High‐Resolution Modeling

“…We also replace model predictions from BSH with other NTOL data sets frequently used in the gravity community. Ocean bottom pressure anomalies from MPIOM that are also applied for the GRACE non-tidal dealiasing model AOD1B RL07 (Shihora et al, 2022) are used with SPOTL to calculate NTOL effects (denoted as AOD7). MPIOM is a baroclinic ocean model based on the primitive equations and operates on a global domain with a moderate temporal and spatial resolution (1.0°tri-polar grid and 3-hourly output) and does not employ data assimilation.…”

“…Hence, for the analysis of terrestrial water storage variations or hazard and geothermal monitoring on local or regional scales, the NTOL signals should be reduced from the observations, provided that the quality of the NTOL signals is sufficient. At present, two operational products based on global ocean models are available for terrestrial gravimetry that are both limited in temporal and spatial resolution: The EOST loading service (Boy, 2024) provides daily NTOL model predictions based on the global ocean model ECCO2 in 0.25°resolution, while the MATLAB toolbox mGlobe (Mikolaj et al, 2016) allows for the computation of NTOL predictions from ocean bottom pressure anomalies of the GRACE Atmosphere and Ocean De-Aliasing Level-1B (AOD1B RL07 and predecessor products) in 3 hr sampling up to spherical harmonic degree and order (d/o) 180 (Dobslaw et al, 2017;Shihora et al, 2022). In general, both operational products show a weak correlation with gravimetric observations and their application does not lead to a significant reduction of the observational signal variation.…”