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Global Gravity-based Groundwater Product (G3P)

The Global Gravity-based Groundwater Product (G3P) provides groundwater storage anomalies (GWSA) from a cross-cutting combination of GRACE/GRACE-FO-based terrestrial water storage (TWS) and storage compartments of the water cycle (WSCs) that are part of the Copernicus portfolio. The data set comprises gridded anomalies of groundwater, TWS, and the WSCs glacier, snow, soil moisture and surface water bodies plus layers containing uncertainty information for the individual data products. All WSCs are spatially filtered with a Gaussian filter to be compatible with TWS. Spatial coverage is global, except Greenland and Antarctica, with 0.5-degree resolution. Temporal coverage is from April 2002 to September 2023 with monthly temporal resolution. Gridded data sets are available as NetCDF files containing variables for the parameter value as anomaly in mm equivalent water height and the parameter’s uncertainty as mm equivalent water height. The latest version of the data is visualized at the GravIS portal: https://gravis.gfz-potsdam.de/gws. From GravIS, the data is also available as area averages for several large river basins and aquifers, as well as for climatically similar regions. G3P was funded by the EU Horizon 2020 programme in response to the call LC-SPACE-04-EO-2019-2020 “Copernicus evolution – Research activities in support of cross-cutting applications between Copernicus services” under grant agreement No. 870353. --------------------------------------------------------------------------------------------- Version History: 10 March 2023: Release of Version v1.11. That version is the initial release of the data (Güntner et al., 2023; https://doi.org/10.5880/G3P.2023.001) (DATE TO BE ADDED) Release of Version v1.12. Temporal coverage has been extended until September 2023.

Global Gravity-based Groundwater Product (G3P)

The Global Gravity-based Groundwater Product (G3P) provides groundwater storage anomalies (GWSA) from a cross-cutting combination of GRACE/GRACE-FO-based terrestrial water storage (TWS) and storage compartments of the water cycle (WSCs) that are part of the Copernicus portfolio. The data set comprises gridded anomalies of groundwater, TWS, and the WSCs glacier, snow, soil moisture and surface water bodies plus layers containing uncertainty information for the individual data products. All WSCs are spatially filtered with a Gaussian filter to be compatible with TWS. Spatial coverage is global, except Greenland and Antarctica, with 0.5-degree resolution. Temporal coverage is from April 2002 to December 2020 with monthly temporal resolution. Gridded data sets are available as NetCDF files containing variables for the parameter value as anomaly in mm equivalent water height and the parameter’s uncertainty as mm equivalent water height. The latest version of the data is visualized at the GravIS portal: http://gravis.gfz-potsdam.de/gws. From GravIS, the data is also available as area averages for several large river basins and aquifers, as well as for climatically similar regions. G3P was funded by the EU Horizon 2020 programme in response to the call LC-SPACE-04-EO-2019-2020 “Copernicus evolution – Research activities in support of cross-cutting applications between Copernicus services” under grant agreement No. 870353. --------------------------------------------------------------------------------------------- Version History: 10 March 2023: Release of Version v1.11. This is the initial release of the data.

Regularized Empirical Variance-Covariance-Matrices for stochastic gravity modeling of 8 major ocean tides

This data publication represents the main outcomes of WP1.200 of Individual Project IP1 and Deliverable D1.1 of the research unit NEROGRAV. The goal of WP1.200 was the realistic representation of modern ocean tide model uncertainties in the form of empirical Variance-Covariance Matrices (VCMs) for the utilization in satellite gravimetric dealiasing. In the following, we describe the data set generation and format. A more detailed description of the processing strategy of the data set can be found in Abrykosov et al. (2021).

AOe07 Variance-Covariance-Matrix

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. As background models are inevitably imperfect, residual errors due to aliasing remain. Accounting for the uncertainties of the background model data has, however, proven to be a useful approach to mitigate the impact of residual aliasing. In light of the changes made in the new release of AOD1B, previous uncertainty assessments are deemed too pessimistic and have been revised in the new time-series of true errors: AOe07. One possible way to include the uncertainty information of background models in gravity field estimation or simulation studies is through the computation and application of a variance-covariance matrix that describes the spatio-temporal error characteristics of the background model. The AOe07 variance-covariance-matrix provides this information through (1) a fully populated matrix up to degree and order 40 as well as (2) a diagonal matrix up to degree and order 180.

TiME22: Periodic Disturbances of the Terrestrial Gravity Potential Induced by Oceanic and Atmospheric Tides

This data publication presents global high-frequency mass variability that is induced by individual oceanic and atmospheric partial tides. While the atmospheric component is obtained by conducting a tidal analysis of numerical weather data data, the oceanic component has been produced using the hydro-dynamical ocean tide model TiME that was recently upgraded in the framework of the DFG-funded Research Group NEROGRAV and can be used for gravimetric applications. The overall goal of this project is to facilitate the analysis of gravimetric data sets (e.g. GRACE/GRACE-FO) by improving the understanding of sensor data, processing strategies, and background models. The data set presented herein contributes to this goal as the here described tidally induced mass variations are an important part of the described background models. As tidal variability is usually described as a superposition of so-called partial tides, the presented mass variations can be attributed to individual partial tide frequencies and are thus represented by individual files for each partial tide frequencies. Here, not only the effect of direct gravitation exerted by the ocean and atmospheric mass is included but also gravity variations due to the elastic yielding of the solid Earth in response to water and atmospheric mass redistribution (the load tide) are allowed for. The information describing the partial tides has been transformed to fully normalized Stokes Coefficients describing harmonic in-phase and quadrature component fields as those are especially handy for gravimetric purposes. Additionally, a set of files that allows further expansion of the ensemble of ocean partial tides via linear admittance theory is provided.

TiME22: Periodic Disturbances of the Terrestrial Gravity Potential Induced by Oceanic and Atmospheric Tides

This data publication presents global high-frequency mass variability that is induced by individual oceanic and atmospheric partial tides. While the atmospheric component is obtained by conducting a tidal analysis of numerical weather data data, the oceanic component has been produced using the hydro-dynamical ocean tide model TiME that was recently upgraded in the framework of the DFG-funded Research Group NEROGRAV ( https://www.lrg.tum.de/iapg/nerograv/) and can be used for gravimetric applications. The overall goal of this project is to facilitate the analysis of gravimetric data sets (e.g. GRACE/GRACE-FO) by improving the understanding of sensor data, processing strategies, and background models. The data set presented herein contributes to this goal as the here described tidally induced mass variations are an important part of the described background models. As tidal variability is usually described as a superposition of so-called partial tides, the presented mass variations can be attributed to individual partial tide frequencies and are thus represented by individual files for each partial tide frequencies. Here, not only the effect of direct gravitation exerted by the ocean and atmospheric mass is included but also gravity variations due to the elastic yielding of the solid Earth in response to water and atmospheric mass redistribution (the load tide) are allowed for. The information describing the partial tides has been transformed to fully normalized Stokes Coefficients describing harmonic in-phase and quadrature component fields as those are especially handy for gravimetric purposes. Additionally, a set of files that allows further expansion of the ensemble of ocean partial tides via linear admittance theory is provided.

Atmosphere and Ocean Non-Tidal Dealiasing Level-1B (AOD1B) Product RL07

The Atmosphere and Ocean De-Aliasing Level-1B (AOD1B) Product provides a priori information about temporal variations in the Earth's gravity field caused by global mass variability in atmosphere and ocean.'It is based on analysis and forecast data of the operational high-resolution global numerical weather prediction (NWP) model from the European Centre for Medium-Range Weather Forecasts (ECMWF) such as ERA5 and ocean bottom pressure from an unconstrained simulation with a global ocean general circulation model that is consistently forced with ECMWF atmospheric data.

Mass variations induced by ocean tide oscillations (TiME21)

This data publication presents global mass variations that are induced by individual ocean partial tides. The data set was produced using the purely-hydrodynamical ocean tide model TiME in the framework of the DFG-project Nerograv\\ (https://www.lrg.tum.de/iapg/nerograv/) and can be used for gravimetric applications. The overall goal of this project is to improve the processing of gravimetric data sets (e.g. GRACE/GRACE-FO) by improving the understanding of sensor data, processing strategies, and background models. The here presented DOI can contribute to this goal as the here described tidally induced mass variations are an important part of the described background models. As ocean tides are usually described as a superposition of so-called partial tides, the presented mass variations can be attributed to single partial tide frequencies and are thus represented for single partial tide frequencies. Here, not only the effect of direct gravitation exerted by the ocean water is included but also gravity variations due to the elastic yielding of the solid earth in response to water mass redistribution (the load tide) are allowed for. The information describing the partial tides has been transformed to fully normalized Stokes Coefficients describing in-phase and quadrature fields as those are especially handy for gravimetric purposes. The next section describes the creation of the data in more detail.

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