GRACE Mascons - Current Products

Name: GSFC.glb.200204_202009_RL06v1.0_OBP-ICE6GD

Summary: Global mascon solution where the GAD product has been restored, meaning the ocean mascons describe ocean bottom pressure (OBP). This product is comparable to the JPL and CSR mascon products.

Grid: 1-arc-degree equal area cells

Available formats: HDF5, ASCII

Name: GSFC.glb.200204_202009_RL06v1.0_SLA-ICE6GD

Summary: Global mascon solution where the GAD product has been restored and the mean GAD over the ocean has been removed, meaning the ocean mascons describe sea level anomalies (SLA), and their sum captures the mass component of global mean sea level change.

Grid: 1-arc-degree equal area cells

Available formats: HDF5, ASCII 

HDF5 format documentation: GSFC_mascons_HDF5_format_RL6v01.pdf 

Important notes about RL06 v1.0:

  • ***As of Feb 2021, the mascon definitions have been modified***
  • Noise and leakage uncertainties are provided (Loomis et al., 2019)
  • Mean removed: 2004.0 – 2010.0
  • Background static field: GGM05C (Ries et al., 2016)
  • Background time-variable field: Trend/annual and Han et al. (2013) coseismic
  • Tide model: GOT4.7 to degree/order 90 (Ray 1999)
  • Atmosphere and ocean de-aliasing: RL06 AOD1B
  • Geocenter correction: JPL TN-13 (Sun et al., 2016)
  • C20 replacement: TN-14 (Loomis et al., 2020)
  • C30 replacement after August 2016: TN-14 (Loomis et al., 2020)
  • Glacial isostatic adjustment correction: ICE-6G_D (Peltier et al., 2018)

 

GSFC solution strategy:

The applied regularization strategy is the critical design parameter for mascon estimation. As described in Loomis et al. (2019), the GSFC monthly regularization matrices are determined by analyzing the spatiotemporal characteristics of the inter-satellite range-acceleration pre-fit residuals. We also use the full monthly mascon resolution operators to compute leakage (i.e. bias) statistics. In conjunction with the provided noise uncertainties, the user can compute the total uncertainty time series for both individual mascons and any desired region. Details are provided in Loomis et al. (2019) and the PDF document above. Also, please see the PDF document for a description of provided metadata that allows the user to quickly identify and sum the mass for many different pre-defined regions and basins. This information is provided with both the HDF5 and ASCII products.

 

When using this data please cite:

Loomis, B.D., Luthcke, S.B. & Sabaka, T.J. (2019) Regularization and error characterization of GRACE mascons. J Geod 93, 1381–1398. https://doi.org/10.1007/s00190-019-01252-y

 

Contact:

Bryant Loomis: Bryant.D.Loomis@nasa.gov
 

References:

  • Dobslaw, H., Bergmann-Wolf, I., Dill, R., et al. (2017), Product Description Document for AOD1B Release 06, GRACE 327-750, GFZ German Research Centre for Geosciences, Department 1: Geodesy and Remote Sensing. https://podaac-tools.jpl.nasa.gov/drive/files/allData/gracefo/docs/AOD1B_PDD_RL06_v6.1.pdf
  • Han, S.-C., R. Riva, J. Sauber, and E. Okal (2013), Source parameter inversion for recent great earthquakes from a decade-long observation of global gravity fields, J. Geophys. Res. Solid Earth, 118, 1240-1267,doi:10.1002/jgrb.50116
  • Loomis, B.D., Luthcke, S.B. & Sabaka, T.J. (2019) Regularization and error characterization of GRACE mascons. J Geod 93, 1381–1398. https://doi.org/10.1007/s00190-019-01252-y
  • Loomis, B. D., K. E. Rachlin, D. N. Wiese, F. W. Landerer, and S. B. Luthcke (2020) Replacing GRACE/GRACE‐FO C30 with satellite laser ranging: Impacts on Antarctic Ice Sheet mass change. Geophys. Res. Lett., 47 (3), https://doi.org/10.1029/2019GL085488
  • Peltier, W. R., D. F. Argus, and R. Drummond (2015), Space geodesy constrains ice-age terminal deglaciation: The global ICE-6G C (VM5a) model, J. Geophys. Res. Solid Earth, 120, 450-487, doi:10.1002/2014JB011176.
  • Ray, R. (1999), A global ocean tide model from Topex/Poseidon altimetry: GOT99.2. NASA Tech. Memo 209478.
  • Ries, J., Bettadpur, S., Eanes, R., et al. (2016) The Combined Gravity Model GGM05C. GFZ Data Services. https://doi.org/10.5880/icgem.2016.002
  • Sun, Y., R. Riva, and P. Ditmar (2016) Optimizing estimates of annual variations and trends in geocenter motion and J2 from a combination of GRACE data and geophysical models, J. Geophys. Res. Solid Earth, 121, https://doi.org/10.1002/2016JB013073