N: 90 S: -90 E: 180 W: -180
Description
This dataset contains gridded monthly global water storage/height anomalies relative to a time-mean, derived from GRACE and GRACE-FO and processed at JPL using the Mascon approach (RL06.3Mv04). A Coastal Resolution Improvement (CRI) filter has been applied to this data set to reduce signal leakage errors across coastlines. For most land hydrology, oceanographic as well as land-ice applications this is the recommend data set for the analysis of surface mass changes. The data are provided in a single data file in netCDF format, with water storage/height anomalies in equivalent water thickness units (cm). The data are derived from solving for monthly gravity field variations on geolocated spherical cap mass concentration functions, rather than global spherical harmonic coefficients. Additionally, realistic geophysical information is introduced during the computation to intrinsically remove correlated errors. Thus, these Mascon grids do not need to be de-correlated or smoothed, like traditional spherical harmonic gravity solutions.
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The complete Mascon solution consists of 4,551 independent estimates of surface mass change that have been derived using an equal-area 3-degree grid of individual mascons. A subset of these individual mascons span coastlines, and contain mixed land and ocean mass change signals. In a post-processing step, the CRI filter is applied to those mixed land/ocean Mascons to separate land and ocean mass. The land mask used to perform this separation is provided in the same directory as this dataset, as are uncertainty values, and the gridded mascon-ID number to enable further analysis. Since the individual mascons act as an inherent smoother on the gravity field, a set of optional gain factors (or scale factors) is provided within the netCDF and can be applied to the solution to study mass change signals at sub-mascon resolution (e.g. for continental hydrology applications). For use-case examples and further background on the gain factors, please see Wiese, Landerer & Watkins, 2016, https://doi.org/10.1002/2016WR019344.
This RL06.3Mv04 is an updated version of the previous Tellus JPL Mascon RL06.1Mv03 (DOI, 10.5067/TEMSC-3JC63). For a detailed description on the Mascon solution, including the mathematical derivation, implementation of geophysical constraints, and solution validation, please see Watkins et al., 2015, doi: 10.1002/2014JB011547. For a detailed description of the CRI filter implementation, please see Wiese et al., 2016, doi:10.1002/2016WR019344.
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Variables
The table below lists the variables contained within a single granule for this dataset. Variables often contain observed or derived geophysical measurements collected from a variety of sources, including remote sensing instruments on satellite and airborne platforms, field campaigns, in situ measurements, and model outputs. The terms variable, parameter, scientific data set, layer, and band have been used across NASA’s Earth science disciplines; however, variable is the designated nomenclature in NASA’s Common Metadata Repository (CMR). Variable metadata attributes such as Name, Description, Units, Data Type, Fill Value, Valid Range, and Scale Factor allow users to efficiently process and analyze the data. The full range of attributes may not be applicable to all variables. Additional information on variable attributes is typically available in the data, user guide, and/or other product documentation.
For questions on a specific variable, please use the Earthdata Forum.
| Name Sort descending | Description | Units | Data Type | Fill Value | Valid Range | Scale Factor | Offset |
|---|---|---|---|---|---|---|---|
| GAD | Coastline Resolution Improvement (CRI) filter is applied | cm | double | -99999 | -28.73597710071 to 46.229601876783 | 1 | N/A |
| land_mask | Land Mask that was used with the CRI filter | binary | double | N/A | N/A | 1 | N/A |
| lat | latitude | degrees_north | double | N/A | -89.75 to 89.75 | 1 | N/A |
| lat_bounds | latitude values at the north and south bounds of each pixel | degrees_north | double | N/A | N/A | 1 | N/A |
| lon | longitude | degrees_east | double | N/A | 0.25 to 359.75 | 1 | N/A |
| lon_bounds | longitude values at the west and east bounds of each pixel | degrees_east | double | N/A | N/A | 1 | N/A |
| lwe_thickness | Coastline Resolution Improvement (CRI) filter is applied | cm | double | -99999 | -2085.878844178 to 1016.7514038309 | 1 | N/A |
| mascon_ID | Mascon identifier mapped to the grid | dimensionless | double | N/A | 1 to 4551 | 1 | N/A |
| scale_factor | Gridded scale factors to be used with mascon solution that has the CRI filter applied; based on CLM data from 2002-2009 | dimensionless | double | -99999 | -99999 to 24.13398846779 | 1 | N/A |
| time | time | days since 2002-01-01T00:00:00Z | double | N/A | N/A | 1 | N/A |
| time_bounds | time bounds for each time value, i.e. the first day and last day included in the monthly solution | days since 2002-01-01T00:00:00Z | double | N/A | N/A | 1 | N/A |
| uncertainty | 1-sigma uncertainty: not for each 0.5 degree grid cell, but for each 3-degree mascon estimate | cm | double | -99999 | 0.22740321267317 to 53.344695985601 | 1 | N/A |