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Full catalog/CLDMSK_L2_VIIRS_NOAA20
CLDMSK_L2_VIIRS_NOAA20·v1·dataset

Where clouds are blocking the view (VIIRS, NOAA-20)

VIIRS/NOAA20 Cloud Mask and Spectral Test Results 6-Min L2 Swath 750m
atmosphere NASA LAADS Level 2 active NetCDF-4
In plain English

What it measures. A judgment, for each spot the sensor sees, of whether the view of Earth's surface is clear or cloud-covered, along with the underlying spectral test results, at 750-meter resolution.

How it's made. Produced from the NOAA-20 VIIRS instrument using the same cloud-detection approach applied to MODIS and other VIIRS sensors, so the records line up across instruments over time.

How & where you'd use it. A consistency-focused cloud layer used to screen out cloudy pixels in other products and to extend long-term cloud records. It is mainly an input behind clear-sky data products.

What's measured

ATMOSPHERE › CLOUDSATMOSPHERE › CLOUDS › CLOUD PROPERTIES › CLOUD FREQUENCYATMOSPHERE › CLOUDS › CLOUD PROPERTIES › CLOUD HEIGHTSPECTRAL/ENGINEERING › INFRARED WAVELENGTHS › INFRARED RADIANCESPECTRAL/ENGINEERING › INFRARED WAVELENGTHS › REFLECTED INFRAREDSPECTRAL/ENGINEERING › VISIBLE WAVELENGTHS › VISIBLE RADIANCE

Coverage & cadence

  • Time span2012-03-01 → ongoing
  • Measured byNOAA-20 (VIIRS)
  • Processing levelLevel 2
  • Spatial extent-180, -90, 180, 90
  • FormatsNetCDF-4
  • 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 VIIRS/NOAA20 Cloud Mask and Spectral Test Results 6-Min L2 Swath 750m product Mask is one of three continuity products designed to sustain the long-term records of both Moderate Resolution Imaging Spectroradiometer (MODIS) and VIIRS heritages. CLDMSK_L2_VIIRS_NOAA20 is the shortname for the NOAA-20 VIIRS incarnation of the Cloud Mask continuity product derived from the MODIS-VIIRS cloud mask (MVCM) algorithm, which itself is based on the MODIS (MOD35) algorithm. MVCM describes a continuity algorithm that is central to both MODIS data (from Terra and Aqua missions) and VIIRS data (from Suomi National Polar-orbiting Partnership (SNPP) and Joint Polar Satellite System missions). Please bear in mind that the term MVCM does not appear as an attribute within the product’s metadata. Implemented to consistently handle MODIS and VIIRS inputs, the NOAA-20 VIIRS collection-1 products use calibration-adjusted NASA VIIRS L1B as inputs. The nominal spatial resolution of the NOAA-20 VIIRS L2 Cloud mask is 750 meters. For more information consult Product Page at: https://cimss.ssec.wisc.edu/MVCM/

Get the data

cldmsk_l2_viirs_noaa20_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="CLDMSK_L2_VIIRS_NOAA20",
    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 LAADS
Browsing CMR needs no login. Downloading or streaming bytes needs a free Earthdata Login + the earthaccess package.