SMAP L4: Global 9 km Soil Moisture from Satellite Data Assimilation

NASA's SMAP mission provides three specialized Level-4 soil moisture products derived from assimilating L-band satellite brightness temperature data into a land surface model. The primary geophysical data product offers 3-hourly global surface and root zone soil moisture estimates on a 9 km EASE-Grid 2.0 projection. Additional products include analysis update diagnostics for the data assimilation process and a static file of land model constants required for interpreting the geophysical fields.

Use Cases

• Monitoring agricultural drought conditions based on root zone soil moisture estimates.
• Validating and improving hydrological models using assimilated satellite observations and model predictions.
• Analyzing land-atmosphere interactions through 3-hourly surface soil moisture time series.
• Interpreting geophysical soil moisture fields using the provided static land model constants.

Strengths

• Data is produced by NASA, a leading space agency, indicating high scientific standards.
• Provides three complementary products (geophysical data, analysis updates, model constants) for different user needs.
• Offers global coverage with a consistent 9 km spatial resolution on the EASE-Grid 2.0 projection.
• Assimilates satellite observations from both ascending and descending passes (approx. 6 a.m. and 6 p.m. local time) for temporal completeness.

Limitations

• Key metadata such as exact temporal coverage, file size, and specific column names are not provided in the sources.
• The 'last updated' date of 2026-04-10 appears to be a future date, indicating a potential metadata error or placeholder value.
• Documentation gaps exist, as descriptions are repeated across platforms without detailed technical specifications.

Provenance

Source

National Aeronautics and Space Administration (NASA)

Collection Method

Satellite remote sensing data from the SMAP mission, assimilated into a land surface model.

Freshness

2026-04-10 19:39:49.757721 (Note: This is a future date and may be erroneous)

Geography

Global coverage