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Description

Scientists at NASA Goddard Space Flight Center generate groundwater and soil moisture drought indicators each week. They are based on terrestrial water storage observations derived from GRACE-FO satellite data and integrated with other observations, using a sophisticated numerical model of land surface water and energy processes.

This data product is GRACE Data Assimilation for Drought Monitoring (GRACE-DA-DM) Global Version 3.0 from a global GRACE and GRACE-FO data assimilation and drought indicator product generation (Li et al., 2019). It varies from the other GRACE-DA-DM products which are from the U.S. GRACE-based drought indicator product generation (Houborg et al., 2012).
The GRACE-DA-DM Global V3.0 is similar to the GRACE-DA-DM U.S. V4.0 product. Both products are based on the Catchment Land Surface Model (CLSM) Fortuna 2.5 version simulation that was created within the Land Information System data assimilation framework (Kumar et al., 2016). GRACE-DA-DM Global V3.0 drought indicator maps are derived from the GLDAS_CLSM025_DA1_D product, at 0.25 degree resolution, forced by ECMWF meteorological data, and assimilated RL06 GRACE and GRACE-FO data from the University of Texas at Austin (Save et al., 2016; Save, 2020). The GRACE-DA-DM U.S. V4.0 is at 0.125 degree, which is based on a model simulation (not published at GES DISC) forced by NLDAS-2 meteorological data and assimilated with RL06 GRACE/GRACE-FO data.
More information on GRACE-DA-DM U.S. V4.0 and previous versions of the data can be found in the README.

The GRACE-DA-DM Global V3.0 data product contains three drought indicators: Groundwater Percentile, Root Zone Soil Moisture Percentile, and Surface Soil Moisture Percentile. These drought indicators express wet or dry conditions as a percentile, indicating the probability of occurrence within the period of record from 1948 to 2014. The drought indicator data are daily, but available only one day (Monday) per week. The data have a spatial resolution of 0.25 x 0.25 degree with global coverage (60S, 180W, 90N, 180E), and a temporal range from February 2003 to present (with a 3-6 month latency). The data are archived in NetCDF format.

The GRACE-DA-DM is an operational project which produces groundwater and soil moisture drought indicators each week. The operational data is available weekly with a 2-9 day latency from the NASA GRACE project home page found under the Documentation tab. The GRACE-DA-DM data distributed here at GESDISC is the final archive version, which is generated after the latest GRACE-FO data are available.

Version Description

The GRACE-DA-DM Version 3.0 used the GRACE RL06 (GRACE; 2002-2017) and GRACE Follow On (GRACE-FO; 2018-present) Mascon solutions, at 0.25 degree resolution, from the University of Texas at Austin (Save et al. 2016; Save 2020). This Global simulation assimilated the versions of GRACE/GRACE-FO data at the time of simulation which were restarted from the last available GRACE data month and extended through present for each week, using the baseline of 2004-2018 mean for Terrestrial Water Storage anomaly computation. GRACE-DA-DM Version 3.0 uses both version 1 and version 2 RL06 GRACE/GRACE-FO data. The RL06 GRACE/GRACE-FO version 1 data, covering April 2002 to August 2019, was released in October 2019 then went through incremental changes each time the GRACE-FO observation was extended monthly, and arrived at the stable version 2 in August 2020 (covering thru 2020/06). The percentile computation was switched to a 7-day moving average climatology instead of monthly, to improve the temporal transition of drought/wetness conditions.

Product Summary

Platforms
Catchment-LSM
Instruments
NOT APPLICABLE
Spatial Extent

N: 90 S: -60 E: 180 W: -180

Location
GLOBAL LAND
Coordinate System
CARTESIAN
Granule Spatial Representation
CARTESIAN
Temporal Extent
2003-02-03 to Present
Data Partner
Goddard Earth Sciences Data and Information Services Center (formerly Goddard DAAC), Terrestrial Information Systems Laboratory, Earth Sciences Division, Science and Exploration Directorate, Goddard Space Flight Center, NASA (NASA/GSFC/SED/ESD/TISL/GESDI
Concept ID
C2283200566-GES_DISC
Data State
ACTIVE
Number of Files/Granules
1200
Processing Level
4
Published
Updated
Science Keywords
Land Surface/Agriculture Indicators ,
Drought Indices ,
Satellite Soil Moisture Index

Citation

Citation is critically important for dataset documentation and discovery. This dataset is openly shared, without restriction, in accordance with the EOSDIS Data Use and Citation Guidance.

Copy Citation

Matthew Rodell and Hiroko Kato Beaudoing, N. A. S. A. G. S. F. C. H. S. L. (2022). Groundwater and Soil Moisture Conditions from GRACE and GRACE-FO Data Assimilation L4 7-days 0.25 x 0.25 degree Global V3.0 [Data set]. NASA Goddard Earth Sciences Data and Information Services Center. https://doi.org/10.5067/SZYMDFZ7TJ4H Date Accessed: 2026-04-18

Documents

READ-ME

GENERAL DOCUMENTATION

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 Description Units Data Type Fill Value Valid Range Scale Factor Offset
gws_inst gws_inst % float32 -999 N/A 1 0
lat lat degrees_north float32 -999 N/A 1 0
lon lon degrees_east float32 -999 N/A 1 0
rtzsm_inst rtzsm_inst % float32 -999 N/A 1 0
sfsm_inst sfsm_inst % float32 -999 N/A 1 0
time time days since 2003-02-02 00:00:00 float64 N/A N/A N/A N/A
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