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Full catalog/PACE_OCI_L3M_KD_NRT
PACE_OCI_L3M_KD_NRT·v3.1·dataset

How deep sunlight reaches in seawater (PACE, near-real-time)

PACE OCI Level-3 Global Mapped Diffuse Attenuation Coefficient of Downwelling Irradiance (KD) - Near Real-time (NRT) Data, version 3.1
ocean NASA OB_CLOUD Level 3 active netCDF-4
In plain English

What it measures. How quickly sunlight fades as it travels down through seawater. Lower values mean clearer water where light reaches deeper; higher values mean murkier water.

How it's made. Derived from the PACE satellite's Ocean Color Instrument using the Lee optical model, then mapped onto a global grid. This is the fast near-real-time version, so its calibration and inputs are less refined than the final product.

How & where you'd use it. People use it to estimate how deep the sunlit zone goes, track coastal water clarity and turbidity, study algae blooms, and feed ocean ecosystem models. Readings can be less reliable in complex coastal or inland waters.

What's measured

Oceans › Ocean Optics › Attenuation/Transmission

Coverage & cadence

  • Time span2024-03-05 → ongoing
  • Measured byPACE (OCI)
  • Processing levelLevel 3
  • Spatial extent-180, -90, 180, 90
  • FormatsnetCDF-4
  • StatusACTIVE

What you can do with it

  • Watch sea-surface temperature and marine heatwaves
  • Spot algal blooms and ocean-colour shifts
  • Support fisheries and coastal monitoring
Official description

The Ocean Biology DAAC produces near real-time (NRT) products using the best-available combination of ancillary data from meteorological and ozone data. As such, the inputs and the calibration used are less than optimal. Near real-time products provide a snapshot of the data during a short time period within a single orbit. The spectral diffuse attenuation coefficient of downwelling irradiance (Kd). Kd is an apparent optical property (AOP) that is derived from IOPs using the Lee bio-optical model. Kd describes how visible light diminishes with depth in the ocean. Lower values indicate clearer water (deeper light penetration); users commonly apply Kd to estimate euphotic depth, track coastal water quality and turbidity, interpret bloom/light environments, and supply inputs to biogeochemical and ecosystem models. As with all ocean-color products, uncertainties can be larger in optically complex coastal or inland waters; refer to the file metadata and algorithm documentation for quality flags and usage notes. Geophysical variables in this suite include: - Kd — Diffuse attenuation coefficient of downwelling irradiance, Lee algorithm (m⁻¹)

Get the data

pace_oci_l3m_kd_nrt_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="PACE_OCI_L3M_KD_NRT",
    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.