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Full catalog/SPL4SMAU
SPL4SMAU·v008·dataset

How wet the soil is, corrected model (SMAP, 9 km)

SMAP L4 Global 3-hourly 9 km EASE-Grid Surface and Root Zone Soil Moisture Analysis Update V008
land NASA NSIDC_CPRD Level 4 active HDF5
In plain English

What it measures. How wet the soil is, both at the surface and in the root zone (the deeper layer plants draw from), as a model-corrected estimate on a 9 km grid every 3 hours. This particular file also shows the corrections made and diagnostic details.

How it's made. Produced by SMAP's Level-4 system, which feeds the satellite's microwave brightness-temperature readings into a land-surface model (GEOS-5) to estimate moisture deeper than the satellite can directly see.

How & where you'd use it. Useful for agriculture, drought and flood assessment, and weather and climate models that need root-zone soil moisture. This 'analysis update' file is mainly for users wanting to inspect how the assimilation adjusted the model, rather than the main geophysical product.

What's measured

LAND SURFACE › SOILS › SOIL MOISTURE/WATER CONTENT › ROOT ZONE SOIL MOISTURELAND SURFACE › SOILS › SOIL MOISTURE/WATER CONTENT › SURFACE SOIL MOISTURE

Coverage & cadence

  • Time span2015-03-31 → ongoing
  • Measured byGEOS-5 (NOT APPLICABLE) · SMAP (SMAP L-BAND RADIOMETER)
  • Processing levelLevel 4
  • Spatial extent-180, -85.044, 180, 85.044
  • FormatsHDF5
  • StatusACTIVE

What you can do with it

  • Track deforestation, fire scars and land-cover change
  • Monitor crop and vegetation health (NDVI/EVI)
  • Map how built-up vs. green an area is over time
Official description

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.

Get the data

spl4smau_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="SPL4SMAU",
    version="008",
    bounding_box=(-122.5, 37.2, -121.8, 37.9),  # your area (W,S,E,N)
    temporal=("2024-01-01", "2024-12-31"),       # your dates
)
files = earthaccess.open(results)   # stream straight from NSIDC_CPRD
Browsing CMR needs no login. Downloading or streaming bytes needs a free Earthdata Login + the earthaccess package.