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Full catalog/PACE_OCI_L2_CLOUD_MASK
PACE_OCI_L2_CLOUD_MASK·v3.1·dataset

Where clouds block the view (PACE)

PACE OCI Level-2 Regional Cloud Mask Data, version 3.1
land NASA OB_CLOUD Level 2 active netCDF-4
In plain English

What it measures. A simple but essential flag for each pixel marking whether the view is blocked by cloud or clear. It comes in a strict version and a more cautious version that also flags pixels right next to clouds.

How it's made. Generated from the OCI instrument on NASA's PACE satellite as a processing step that screens each scene for clouds.

How & where you'd use it. A behind-the-scenes tool that lets other PACE products run only where they should, such as keeping clouds out of ocean color and chlorophyll measurements. Most people use it indirectly through cleaner downstream products.

What's measured

Spectral/Engineering › Visible WavelengthsAtmosphere › Clouds

Coverage & cadence

  • Time span2024-03-05 → ongoing
  • Measured byPACE (OCI)
  • Processing levelLevel 2
  • Spatial extent-180, -90, 180, 90
  • FormatsnetCDF-4
  • 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 Cloud Mask identifies whether pixels are cloud-covered or not. This is important because algorithms to determine cloud properties should only run on cloudy pixels, and other algorithms that require clear-sky pixels need to screen clouds out. In practice, users apply cloud_flag for strict cloud removal and cloud_flag_dilated when they want a conservative mask that reduces cloud-edge artifacts in downstream products (e.g., Rrs, chlorophyll). The CLDMASK is used operationally as the "cloud and cloud-adjacent" screen. Core geophysical variables in this suite include: - cloud_flag - Cloud mask (bitmask; identifies cloud-contaminated pixels) - cloud_flag_dilated - Cloud or cloud-adjacent pixel mask (bitmask; includes surrounding pixels) - l2_flags - Level-2 Processing Flags (bitmask)

Get the data

pace_oci_l2_cloud_mask_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="PACE_OCI_L2_CLOUD_MASK",
    version="3.1",
    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 OB_CLOUD
Browsing CMR needs no login. Downloading or streaming bytes needs a free Earthdata Login + the earthaccess package.