GRACE/GRACE-FO Mascons

Monthly mascon products

Name: GSFC.glb.200204_202207_RL06v2.0_OBP-ICE6GD

Data Span: April 2002 - July 2022

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_202207_RL06v2.0_SLA-ICE6GD

Data Span: April 2002 - July 2022

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 

Name: GSFC.glb.200204_202207_RL06v2.0_OBP-ICE6GD_HALFDEGREE.nc

Data Span: April 2002 – July 2022

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. The 1-arc-degree equal area values have been placed on an equal angle 0.5x0.5 degree grid. Land values are determined with a least squares estimator that conserves mass over each region, while ocean values have been interpolated/extrapolated.

Grid: 0.5x0.5 degrees

Available formats: NetCDF

 

High-resolution trend mascon products

Name: GSFC_highres_trends_GRACE_200204-201608_RL06v1.0_GSM-ICE6GD

Data Span: April 2002 - August 2016

Summary: High-resolution global mascon trend solution, where each mascon regression model (including the trend) has been directly estimated from the full span of Level 1B data. The GAD product has not been restored, meaning the ocean mascons are consistent with the Level 2 GSM product information.

Grid: 1-arc-degree equal area cells

Available formats: ASCII 

Name: GSFC_highres_trends_GRACE_200204-201608_GFO_201806-202009_RL06v1.0_GSM-ICE6GD

Data Span: April 2002 - August 2016 (GRACE); June 2018 - September 2020 (GRACE-FO)

Summary: High-resolution global mascon trend solution, where each mascon regression model (including the trend) has been directly estimated from the full span of Level 1B data. The GAD product has not been restored, meaning the ocean mascons are consistent with the Level 2 GSM product information.

Grid: 1-arc-degree equal area cells

Available formats: ASCII

HDF5 format documentation: GSFC_mascons_HDF5_format_RL6v02.pdf 

Important notes about RL06v2.0:

  • GRACE-FO months use the new ACH0 accelerometer transplant files (solutions made after Apr 2022)
  • The mascon location definitions were modified for RL06 solutions (solutions made after Feb 2021)
  • 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: (Sun et al., 2016)
  • C20 replacement: TN-14 (Loomis et al., 2020)
  • C30 replacement beginning August 2016: TN-14 (Loomis et al., 2020)
  • Glacial isostatic adjustment correction: ICE-6G_D (Peltier et al., 2018)

 

When using the monthly 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

When using the high-resolution trend data please cite:

Loomis, B. D., D. Felikson, T. J. Sabaka, and B. Medley (2021). High‐spatial‐resolution mass rates from GRACE and GRACE‐FO: Global and ice sheet analyses.   Journal of Geophysical Research: Solid Earth, https://doi.org/10.1029/2021JB023024

 

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