Whether the ground is frozen or thawed, daily (SMAP, 36 km)

In plain English

What it measures. Whether the land surface is frozen or thawed each day, across the globe and the Northern Hemisphere, on a 36 km grid.

How it's made. Derived from the microwave glow (brightness temperature) the ground emits as seen by SMAP's radiometer on its morning and evening passes, then snapped to an equal-area grid.

How & where you'd use it. Marks the start and end of the growing season and frozen-ground periods, useful for ecology, agriculture, and water-cycle studies.

What's measured

CRYOSPHERE › SNOW/ICE › FREEZE/THAW › TRANSITION DIRECTION

Coverage & cadence

Time span2015-03-31 → ongoing
Measured bySMAP (SMAP L-BAND RADIOMETER)
Processing levelLevel 3
Spatial extent-180, 45, 180, 85.044
FormatsHDF5
StatusACTIVE

What you can do with it

Measure sea ice, snow cover and glaciers
Watch ice-sheet elevation change
Track freeze/thaw and permafrost

Official description

This Level-3 (L3) product provides a daily composite of landscape freeze/thaw conditions retrieved by the Soil Moisture Active Passive (SMAP) radiometer from 6:00 a.m. descending and 6:00 p.m. ascending half-orbit passes. SMAP L-band brightness temperatures are used to derive freeze/thaw state and transition data, which are then resampled to both an Earth-fixed, Northern Hemisphere azimuthal 36 km Equal-Area Scalable Earth Grid (EASE-Grid 2.0), and to an Earth-fixed global 36 km EASE-Grid 2.0.

Get the data

spl3ftp_access.py

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

results = earthaccess.search_data(
    short_name="SPL3FTP",
    version="004",
    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