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Full catalog/N18_AVH02C1
N18_AVH02C1·v6·dataset

Raw light bouncing off Earth's top of atmosphere (NOAA-18, daily)

NOAA-18 AVHRR Top-of-Atmosphere Reflectance Daily L3 Global 0.05 Deg. CMG
atmosphere NASA LAADS Level 3 HDF-EOS
In plain English

What it measures. How much sunlight bounces back to the sensor from the top of Earth's atmosphere each day, before any correction for the atmosphere itself.

How it's made. Generated from the AVHRR sensor on the NOAA-18 satellite as part of a long-term climate data record, gridded globally at about 5 km resolution from an earlier surface-reflectance product.

How & where you'd use it. A foundational input for long-term vegetation and climate records; most people use it through derived products like vegetation indexes rather than directly.

What's measured

ATMOSPHERE › ATMOSPHERIC RADIATION › REFLECTANCE › TOP OF ATMOSPHERE (TOA) REFLECTANCELAND SURFACE › SURFACE RADIATIVE PROPERTIES › REFLECTANCESPECTRAL/ENGINEERING › INFRARED WAVELENGTHS › BRIGHTNESS TEMPERATURE

Coverage & cadence

  • Time span2005-07-01 → 2010-01-31
  • Measured byNOAA-18 (AVHRR)
  • Processing levelLevel 3
  • Spatial extent-180, -90, 180, 90
  • FormatsHDF-EOS
  • StatusACTIVE

What you can do with it

  • Map air pollutants — NO₂, aerosols, ozone
  • Track greenhouse gases and Earth's energy budget
  • Feed weather and air-quality analysis
Official description

The Long-Term Data Record (LTDR) produces, validates, and distributes a global land surface climate data record (CDR) that uses both mature and well-tested algorithms in concert with the best-available polar-orbiting satellite data from past to the present. The CDR is critically important to studying global climate change. The LTDR project is unique in that it serves as a bridge that connects data derived from the NOAA Advanced Very High Resolution Radiometer (AVHRR), the EOS Moderate resolution Imaging Spectroradiometer (MODIS), the Suomi National Polar-orbiting Partnership (SNPP) Visible Infrared Imaging Radiometer Suite (VIIRS), and Joint Polar Satellite System (JPSS) VIIRS missions. The LTDR draws from the following eight AVHRR missions: NOAA-7, NOAA-9, NOAA-11, NOAA-14, NOAA-16, NOAA-18, NOAA-19, and MetOp-B. Currently, the project generates a daily surface reflectance product as the fundamental climate data record (FCDR) and derives daily Normalized Differential Vegetation Index (NDVI) and Leaf-Area Index/fraction of absorbed Photosynthetically Active Radiation (LAI/fPAR) as two thematic CDRs (TCDR). LAI/fPAR was developed as an experimental product. The NOAA-18 AVHRR Top-of-Atmosphere Reflectance Daily L3 Global 0.05Deg CMG, short-name N18_ AVH02C1 is generated from GIMMS Advanced Processing System (GAPS) BRDF-corrected Surface Reflectance product (AVH01C1). The N18_ AVH02C1 consist of Top-of-atmosphere reflectance for bands 1 and 2, data Quality flags, angles (solar zenith, view zenith, and relative azimuth), thermal data (thermal bands 3, 4 and 5), and additional data (scan time).

Get the data

n18_avh02c1_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="N18_AVH02C1",
    version="6",
    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 LAADS
Browsing CMR needs no login. Downloading or streaming bytes needs a free Earthdata Login + the earthaccess package.