NASA SMERGE: Root Zone Soil Moisture for the Continental U.S., 1979-2019

Continental United States root zone soil moisture data at a 0.125-degree resolution, produced daily from January 1979 to May 2019. The SMERGE product merges land surface model output from NLDAS with satellite retrievals from the European Space Agency Climate Change Initiative. This dataset is the recommended replacement for the AMSR-E/Aqua root zone soil moisture product.

Use Cases

• Modeling drought conditions and agricultural water stress based on the 0-40 cm root zone soil moisture layer.
• Analyzing long-term soil moisture trends and anomalies based on the nearly four-decade temporal coverage.
• Validating and improving land surface and hydrological models based on the merged model-satellite data product.
• Studying the impact of climate variability on soil water storage across the continental U.S. based on the high-resolution spatial grid.

Strengths

• Long temporal coverage spanning nearly four decades (January 1979 to May 2019).
• High spatial resolution of 0.125 degrees covering the entire continental United States.
• Product merges two data sources (land surface model and satellite retrievals), which likely improves estimation quality.
• Explicitly stated as the recommended replacement for a legacy product, indicating official support.

Limitations

• Description metadata is limited; actual data quality requires manual inspection after download.
• Column-level documentation is absent; field semantics must be inferred after download.
• Data freshness is limited, with the time series ending in May 2019.

Provenance

Source

NASA, developed by merging NLDAS model output with ESA Climate Change Initiative satellite data.

Collection Method

Merging of land surface model output and satellite retrievals.

Time Range

January 1979 to May 2019

Freshness

Daily time-step, but the time series ends in May 2019.

Geography

Continental United States