How wet the soil is (SMAP radar, 3 km) — SPL2SMA

In plain English

What it measures. How wet the soil is across the world's land surface, plus extra information like surface temperature and how much water is held in vegetation.

How it's made. Retrieved from the active radar on NASA's SMAP satellite during its early-morning passes, with the data placed on a 3-km global grid.

How & where you'd use it. Soil moisture matters for drought tracking, flood forecasting, crop planning, and weather and climate models. This particular radar-based version is one input among SMAP's soil moisture products.

What's measured

SPECTRAL/ENGINEERING › RADAR › SIGMA NAUGHTLAND SURFACE › SOILS › SOIL MOISTURE/WATER CONTENT

Coverage & cadence

Time span2015-04-13 → 2015-07-07
Measured bySMAP (SMAP L-BAND RADAR)
Processing levelLevel 2
Spatial extent-180, -85.044, 180, 85.044
FormatsHDF5
StatusCOMPLETE

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) active radar during 6:00 a.m. descending half-orbit passes, as well as ancillary data such as surface temperature and vegetation water content. Input backscatter data used to derive soil moisture are resampled to an Earth-fixed, global, cylindrical 3 km Equal-Area Scalable Earth Grid, Version 2.0 (EASE-Grid 2.0).

Get the data

spl2sma_access.py

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

results = earthaccess.search_data(
    short_name="SPL2SMA",
    version="003",
    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 Radar Half-Orbit 3 km EASE-Grid Soil Moisture, Version 3 User Guide VIEW RELATED INFORMATION
SPL2/3SMA Assessment Report Version 4 [2017] VIEW RELATED INFORMATION
SMAP Ancillary Data Report: Landcover Classification [2013] VIEW RELATED INFORMATION