Radar reflections off land and ice (SMAP, twice daily)

In plain English

What it measures. How strongly land and ice surfaces bounce radar signals back to the satellite, mapped twice a day across polar and mid-latitude regions.

How it's made. Built from radar data collected by NASA's SMAP satellite, combined and sharpened using image-reconstruction methods and laid out on a fixed map grid at either 25 km or 3 km detail.

How & where you'd use it. Radar reflections reveal surface conditions like soil wetness, frozen versus thawed ground, and vegetation, supporting water and climate research.

What's measured

SPECTRAL/ENGINEERING › RADAR › SIGMA NAUGHT

Coverage & cadence

Time span2015-04-13 → 2015-07-12
Measured bySMAP (SMAP L-BAND RADAR)
Processing levelLevel 3
Spatial extent-180, -90, 180, 90
FormatsnetCDF-4
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 data set contains twice-daily synthetic aperture radar (SAR) and enhanced-resolution scatterometer radar backscatter derived from SMAP radar data. Data are available on the Northern Hemisphere, Southern Hemisphere, Temperate, and Mid-Latitude (sub-set of Global) EASE-Grid 2.0 projections and as either 25 km or 3.125 km resolution grids. This new product uses the drop-in-the bucket gridding (GRD) algorithm and Scatterometer Image Reconstruction (SIR) algorithm to process the individual swath-based data from the input data sets into twice-daily images, producing SAR images (high-resolution), slice and footprint images (both lower-resolution), respectively. Note, that as a companion product, the radiometer form of the SIR algorithm (rSIR) was used to derive brightness temperatures from SMAP radiometer data for the <i>SMAP Radiometer Twice-Daily rSIR-Enhanced EASE-Grid 2.0 Brightness Temperatures, Version 2</i>, data set (<a href="https://nsidc.org/data/nsidc-0738">NSIDC-0738</a>).

Get the data

nsidc-0774_access.py

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

results = earthaccess.search_data(
    short_name="NSIDC-0774",
    version="1",
    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.

What's measured

Coverage & cadence

What you can do with it

Get the data

Official links