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Description

Smerge-Noah-CCI root zone soil moisture 0-40 cm L4 daily 0.125 x 0.125 degree V2.0 is a multi-decadal root-zone soil moisture product. Smerge is developed by merging the North American Land Data Assimilation System (NLDAS) land surface model output with surface satellite retrievals from the European Space Agency Climate Change Initiative. The data have a 0.125 degree resolution at a daily time-step, covering the entire continental United States and spanning nearly four decades (January 1979 to May 2019).

This data product contains root-zone soil moisture of 0 - 40 cm layer, Climate Change Initiative (CCI) derived soil moisture anomalies of 0-40 cm layer, and a soil moisture data estimation flag.

This data product is the recommended replacement for the AMSR-E/Aqua root zone soil moisture L3 1 day 25 km x 25 km descending and 2-Layer Palmer Water Balance Model V001 product (LPRM_AMSRE_D_RZSM3), which will be removed from archive on June 27, 2022. Smerge provides a better root zone soil moisture estimation because it has higher data quality and longer temporal coverage.

Version Description

SMERGE version 2.0 is an improvement of the previous version v1.0 with a DOI as 10.5067/NRJWAMBMN6JD (decommissioned on November 15, 2019). The main differences between SMERGE v1.0 and SMERGE v2.0 are the addition of a new variable, CCI derived soil moisture anomalies of 0-40 cm layer, and an additional year of data for 2016.

Product Summary

Platforms
SMERGE
Instruments
NOT APPLICABLE
Spatial Extent

N: 53 S: 25 E: -67 W: -125

Geographic Region
NORTH AMERICA
Coordinate System
CARTESIAN
Granule Spatial Representation
CARTESIAN
Temporal Extent
1979-01-02 to 2019-05-10
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
C1569839798-GES_DISC
Data State
COMPLETE
Number of Files/Granules
14739
Processing Level
4
Published
Updated
Science Keywords
Soil Moisture/Water Content ,
Root Zone Soil Moisture

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

Crow, W., USDA ARS, Tobin, K., & Texas AM IU. (2018). Smerge-Noah-CCI root zone soil moisture 0-40 cm L4 daily 0.125 x 0.125 degree V2.0 [Data set]. NASA Goddard Earth Sciences Data and Information Services Center. https://doi.org/10.5067/PAVQY1KHTMUT Date Accessed: 2025-12-14

Documents

READ-ME

Variables

Variables are a set of physical properties whose values determine the characteristics or behavior of something. For example, temperature and pressure are variables of the atmosphere. Parameters and variables can be used interchangeably. Variable level attributes provide individual information for each variable.

The Name in this table is the variable name. Fill value indicates missing or undefined data points in a variable. Valid range is the range of values the variable can store. Scale factor is used to increase or decrease the size of an object and can be used to correct for distortion. For questions on a specific variable, please use the Earthdata Forum.

Name Description Units Data Type Fill Value Valid Range Scale Factor
CCI_ano CCI_ano m3/m3 float64 9999.9 N/A N/A
lat lat degrees_north float64 N/A N/A N/A
lon lon degrees_east float64 N/A N/A N/A
RZSM RZSM m3/m3 float64 9999.9 N/A N/A
smflag smflag N/A int8 127 N/A N/A
time time days since 1979-01-01 00:00:00 float64 N/A N/A N/A
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