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Full catalog/MCD43D40
MCD43D40·v061·dataset

Snow flag for surface-reflectance quality (MODIS, daily, 30 arc-sec)

MODIS/Terra+Aqua BRDF/Albedo QA SnowStatus Daily L3 Global 30ArcSec CMG V061
land NASA LPCLOUD Level 3 active HDF-EOS2
In plain English

What it measures. A simple per-pixel flag that says whether the ground was snow-covered or snow-free when the land's reflectance was measured. It's a quality marker, not a measurement of any physical quantity itself.

How it's made. Produced daily from 16 days of combined Terra and Aqua MODIS observations, gridded worldwide at about 1 km, as one single data layer in a larger family of land-reflectance products.

How & where you'd use it. A behind-the-scenes helper: it tells scientists whether snow was present so they can correctly interpret companion land-surface and albedo products. Most people use it indirectly rather than on its own.

What's measured

LAND SURFACE › SURFACE RADIATIVE PROPERTIES › ALBEDOLAND SURFACE › SURFACE RADIATIVE PROPERTIES › ANISOTROPYLAND SURFACE › SURFACE RADIATIVE PROPERTIES › REFLECTANCE

Coverage & cadence

  • Time span2000-02-16 → ongoing
  • Measured byTerra (MODIS) · Aqua (MODIS)
  • Processing levelLevel 3
  • Spatial extent-180, -90, 180, 90
  • FormatsHDF-EOS2
  • StatusACTIVE

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 MCD43D40 Version 6.1 Bidirectional Reflectance Distribution Function and Albedo (BRDF/Albedo) QA Snow Status dataset is produced daily using 16 days of Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) data at 30 arc second (1,000 meter (m)) resolution. Data are temporally weighted to the ninth day which is reflected in the Julian date in the file name. This Climate Modeling Grid (CMG) product covers the entire globe for use in climate simulation models. Due to the large file size, each MCD43D project contains just one data layer. MCD43D40 provides snow cover information for the MCD43D products. Users are urged to use the band specific quality flags to isolate the highest quality full inversion results for their own science applications as described in the [User Guide](https://www.umb.edu/spectralmass/modis-user-guide-v006-and-v0061/mcd43d-cmg-30-arc-second-products/). MCD43D40 contains the snow status quality layer which identifies each pixel as either “Snow-free Albedo Retrieved” or “Snow Albedo Retrieved” for the acquisition period. Known Issues * For complete information about known issues please refer to the [MODIS/VIIRS Land Quality Assessment website](https://landweb.modaps.eosdis.nasa.gov/knownissue?sensor=MODIS&sat=TerraAqua&as=61).

Get the data

mcd43d40_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="MCD43D40",
    version="061",
    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.