Publication Date:
2023-01-19
Description:
The Atmosphere and Ocean De‐Aliasing Level‐1B (AOD1B) product provides a priori information about temporal variations in the Earth's gravity field induced by non‐tidal circulation processes in atmosphere and ocean. It is routinely applied as a background model in the Gravity Recovery and Climate Experiment (GRACE)/GRACE Follow‐On (GRACE‐FO) satellite gravimetry data processing. We here present three new datasets in preparation for the upcoming release RL07 of AOD1B, that are based on either the global ERA5 reanalysis or the ECMWF operational data together with simulations from the Max‐Planck‐Institute for Meteorology general circulation model forced consistently with the fields of the same atmospheric data set. The oceanic simulations newly include an updated bathymetry around Antarctica including cavities under the ice shelves, the explicit implementation of the feedback effects of self‐attraction and loading to ocean dynamics as well as a refined harmonic tidal analysis. Comparison to the current release of AOD1B in terms of GRACE‐FO K‐band range‐acceleration pre‐fit residuals, LRI line‐of‐sight gravity differences and band‐pass filtered altimetry data reveals an overall improvement in the representation of the high‐frequency mass variability. Potential benefits of enhancing the temporal resolution remain inconclusive so that the upcoming release 07 will be sampled again every 3 hr.
Description:
Plain Language Summary:
Satellite gravimetry missions such as the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow‐On (GRACE‐FO), which play a vital role in the monitoring of the Earth's mass transports, require a priori background information on the high‐frequency mass variations which can not be resolved by the monthly gravity solutions. The Atmosphere and Ocean De‐Aliasing Level‐1B (AOD1B) data product provides the required background information for non‐tidal high‐frequency mass changes in the atmosphere and oceans. However, the accurate representation of these mass variations remains challenging and deficiencies in the background models have a significant impact on the overall gravity field errors. Thus, we here present three new datasets in preparation for an upcoming release of AOD1B (RL07). The datasets improve over previous releases by incorporating the effects of the self attraction and solid earth deformation caused by anomalous water masses (SAL), an improved representation of the bathymetry and atmospheric forcing around Antarctica, making use of the new ERA5 atmospheric reanalysis as well as an updated estimation and subtraction of atmospherically induced tidal signals. We compare the new data to the previous release of AOD1B using microwave‐ and laser‐ranging data from GRACE‐FO as well as Jason‐3 altimetry data and show a global improvement in the representation of high‐frequency mass changes.
Description:
Key Points:
Atmospheric mass variability from ECMWF’s latest global reanalysis ERA5 is discussed.
Ocean response from Max‐Planck‐Institute for Meteorology Ocean Model includes feedback of self‐attraction and loading.
Applicable for Gravity Recovery and Climate Experiment (GRACE), GRACE Follow‐On, and legacy data from SLR satellites.
Description:
Deutsche Forschungsgemeinschaft, DFG
http://dx.doi.org/10.13039/501100001659
Description:
https://doi.org/10.5880/GFZ.1.3.2022.003
Keywords:
ddc:526.7
;
AOD1B RL07
;
GRACE
;
ERA5
;
self‐attraction and loading
;
satellite gravimetry
Language:
English
Type:
doc-type:article
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