How wet the soil is (SMAP, 36 km) — SPL2SMP

In plain English

What it measures. Estimates how much moisture is in the top layer of soil across global land, mapped in roughly 36 km blocks. It captures conditions at the dawn and dusk passes of the satellite.

How it's made. Derived from the SMAP satellite's passive microwave radiometer, which senses faint natural microwave energy from the land; those readings are gridded and then converted into soil moisture estimates.

How & where you'd use it. Useful for tracking drought, informing farming and water management, and feeding weather and flood forecasts.

What's measured

SPECTRAL/ENGINEERING › MICROWAVE › BRIGHTNESS TEMPERATURELAND SURFACE › SOILS › SOIL MOISTURE/WATER CONTENT › SURFACE SOIL MOISTURE

Coverage & cadence

Time span2015-03-31 → ongoing
Measured bySMAP (SMAP L-BAND RADIOMETER)
Processing levelLevel 2
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

This Level-2 (L2) soil moisture product provides estimates of global land surface conditions retrieved by the Soil Moisture Active Passive (SMAP) passive microwave radiometer during 6:00 a.m. descending and 6:00 p.m. ascending half-orbit passes. SMAP L-band brightness temperatures are resampled to an Earth-fixed, global, cylindrical 36 km Equal-Area Scalable Earth Grid, Version 2.0 (EASE-Grid 2.0) [and made available as the SPL1CTB product], and the gridded brightness temperatures are then used to derive gridded soil moisture data.

Get the data

spl2smp_access.py

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

results = earthaccess.search_data(
    short_name="SPL2SMP",
    version="009",
    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.

Official links

Search and order NASA Earth Science data using spatial and temporal filters. Reformatting, reprojecting, and subsetting options are available for some data sets. GET DATA
Quickly download a few files using a web browser, or access data through a command-line utility such as WGET. GET DATA
Search data by spatial and/or temporal ranges or file name. Choose from various download options, including a Python script. GET DATA
A Python library to search and access NASA Earth science data with just a few lines of code GET DATA
Find more data access options and help resources. VIEW RELATED INFORMATION
SMAP L2 Radiometer Half-Orbit 36 km EASE-Grid Soil Moisture, Version 9 User Guide VIEW RELATED INFORMATION
SPL2/3SMP/_E Algorithm Theoretical Basis Document [2021] VIEW RELATED INFORMATION
SPL2SMP Product Specification Document [2021] VIEW RELATED INFORMATION