Dates of Images:

September 22, 2026

Date of Next Image:

Unknown

Summary:

SMAP Level-4 (L4) surface and root zone soil moisture (L4_SM) data are provided in three products. The SMAP L4 Global 3-hourly 9 km EASE-Grid Surface and Root Zone Soil Moisture Geophysical Data (SPL4SMGP, DOI: 10.5067/T5RUATAQREF8) product is a series of 3-hourly time average geophysical land surface fields that are output by the L4_SM algorithm. It is likely of primary interest to most users. The SMAP L4 Global 3-hourly 9 km EASE-Grid Surface and Root Zone Soil Moisture Analysis Update (SPL4SMAU, DOI: 10.5067/02LGW4DGJYRX) product provides diagnostics from the land surface analysis updates. It consists of a series of 3-hourly instantaneous (or snapshot) files that contain the assimilated SMAP observations, the corresponding land model predictions and analysis estimates, and additional data assimilation diagnostics. Lastly, the SMAP L4 Global 9 km EASE-Grid Surface and Root Zone Soil Moisture Land Model Constants (SPL4SMLM, DOI: 10.5067/PXQIBL2ALDZD) product provides static (time-invariant) land surface model constants that will be needed by some users for further interpretation of the geophysical land surface fields. This product consists of only one granule (file) per L4_SM data product version (as defined by a distinct Science Version ID). For each product, SMAP L-band brightness temperature data from descending and ascending half-orbit satellite passes (approximately 6:00 a.m. and 6:00 p.m. local solar time, respectively) are assimilated into a land surface model that is gridded using an Earth-fixed, global cylindrical 9 km Equal-Area Scalable Earth Grid, Version 2.0 (EASE-Grid 2.0) projection.

Parameter(s):

ROOT ZONE SOIL MOISTURE

SURFACE SOIL MOISTURE

Platform(s):

GEOS-5SMAP

Sensor(s):

NOT APPLICABLE (root zone)

SMAP L-BAND RADIOMETER (surface soil moisture)

Data Format(s):

GeoTIFF

Temporal Resolution:

3 hour

Spatial Resolution:

9 km

Spatial Reference System(s):

WGS 84 / NSIDC EASE-Grid 2.0 Global

EPSG:6933

Dates of Images:

September 22, 2026

Date of Next Image:

Unknown

Summary:

SMAP Level-4 (L4) surface and root zone soil moisture (L4_SM) data are provided in three products. The SMAP L4 Global 3-hourly 9 km EASE-Grid Surface and Root Zone Soil Moisture Geophysical Data (SPL4SMGP, DOI: 10.5067/T5RUATAQREF8) product is a series of 3-hourly time average geophysical land surface fields that are output by the L4_SM algorithm. It is likely of primary interest to most users. The SMAP L4 Global 3-hourly 9 km EASE-Grid Surface and Root Zone Soil Moisture Analysis Update (SPL4SMAU, DOI: 10.5067/02LGW4DGJYRX) product provides diagnostics from the land surface analysis updates. It consists of a series of 3-hourly instantaneous (or snapshot) files that contain the assimilated SMAP observations, the corresponding land model predictions and analysis estimates, and additional data assimilation diagnostics. Lastly, the SMAP L4 Global 9 km EASE-Grid Surface and Root Zone Soil Moisture Land Model Constants (SPL4SMLM, DOI: 10.5067/PXQIBL2ALDZD) product provides static (time-invariant) land surface model constants that will be needed by some users for further interpretation of the geophysical land surface fields. This product consists of only one granule (file) per L4_SM data product version (as defined by a distinct Science Version ID). For each product, SMAP L-band brightness temperature data from descending and ascending half-orbit satellite passes (approximately 6:00 a.m. and 6:00 p.m. local solar time, respectively) are assimilated into a land surface model that is gridded using an Earth-fixed, global cylindrical 9 km Equal-Area Scalable Earth Grid, Version 2.0 (EASE-Grid 2.0) projection.

Parameter(s):

ROOT ZONE SOIL MOISTURE

SURFACE SOIL MOISTURE

Platform(s):

GEOS-5SMAP

Sensor(s):

NOT APPLICABLE (root zone)

SMAP L-BAND RADIOMETER (surface soil moisture)

Data Format(s):

GeoTIFF

Temporal Resolution:

3 hour

Spatial Resolution:

9 km

Spatial Reference System(s):

WGS 84 / NSIDC EASE-Grid 2.0 Global

EPSG:6933

Credits:

Funding was provided by the NASA SMAP Mission. Computational resources were provided by the NASA High-End Computing program through the NASA Center for Climate Simulation. The generation and dissemination of SMAP data products possible includes staff at GSFC, JPL, and NSIDC.