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Full catalog/AST_09T
AST_09T·v004·dataset

Heat energy rising off the land surface (ASTER)

ASTER L2 Surface Radiance TIR V004
land NASA LPCLOUD Level 2 COG
In plain English

What it measures. How much thermal (heat) energy leaves the land surface, measured in five infrared bands at 90 meter resolution. It captures both the heat the surface gives off and the heat it reflects, and is only valid for clear, cloud-free pixels.

How it's made. Generated from the thermal infrared bands of the ASTER instrument on NASA's Terra satellite, then corrected for atmospheric effects using a radiative-transfer model.

How & where you'd use it. A building-block input used to derive higher-level products like surface temperature and emissivity, which in turn support studies of land heat, geology, and the environment.

What's measured

SPECTRAL/ENGINEERING › INFRARED WAVELENGTHS › INFRARED FLUXSPECTRAL/ENGINEERING › INFRARED WAVELENGTHS › INFRARED IMAGERYSPECTRAL/ENGINEERING › INFRARED WAVELENGTHS › INFRARED RADIANCESPECTRAL/ENGINEERING › INFRARED WAVELENGTHS › THERMAL INFRARED

Coverage & cadence

  • Time span2000-03-04 → 2026-01-16
  • Measured byTerra (ASTER)
  • Processing levelLevel 2
  • Spatial extent-180, -90, 180, 90
  • FormatsCOG
  • 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

The Terra Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Surface Radiance TIR (AST_09T) is generated using the five Thermal Infrared (TIR) bands (acquired either during the day or nighttime) between 8 and 12 µm spectral range. It provides surface-leaving radiance for the TIR bands at a spatial resolution of 90 meters, which includes both surface-emitted and surface-reflected components. It also provides the downwelling sky irradiance values (in W/m2/µm) for each of the TIR bands. This product is atmospherically corrected, and the surface-leaving radiance is of known accuracy and valid only for clear-sky scenes (cloud-free pixels). This atmospherically corrected product provides the input for generating two other higher level products: surface spectral emissivity and surface kinetic temperature. The algorithm to correct atmospheric effects involves two elements. First, it uses a radiative transfer model—the Moderate Resolution Transmittance Code (MODTRAN)—which can estimate the magnitude of atmospheric emission, absorption, and scattering. MODTRAN calculates atmospheric transmittance and radiance for frequencies from 0 to 50,000 cmˉ¹ at moderate spectral resolution. Second, it identifies and incorporates all the necessary atmospheric parameters applicable to the location and time for which the measurements require correction, including temperature, water vapor, elevation, ozone, and aerosols. Acquisitions for AST_09T ended on January 16, 2026, at 05:10:45 UTC, when the ASTER TIR instrument was permanently turned off due to power limitations on the Terra spacecraft. More information is available in this [NASA Science News Brief](https://science.nasa.gov/blogs/science-news/2026/02/12/terra-adjusts-instrument-operations-to-extend-mission-life/).  Known Issues * Level 2 products that are on the international date line/anti-meridian have incorrect bounding coordinates for the UTM zone defined in the file metadata. * Data acquisition gaps: On November 28, 2024, one of Terra's power-transmitting shunt units failed. As a result, there was insufficient power to maintain functionality of the ASTER instrument. ASTER resumed acquisitions for the TIR bands on April 15, 2025. Users should note the data gap in ASTER acquisitions from November 28, 2024, through April 15, 2025, for TIR acquisitions.

Get the data

ast_09t_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="AST_09T",
    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 LPCLOUD
Browsing CMR needs no login. Downloading or streaming bytes needs a free Earthdata Login + the earthaccess package.