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Full catalog/VIIRSJ1_L2_OC_NRT
VIIRSJ1_L2_OC_NRT·v2022.0·dataset

Ocean color and tiny plant life, live (VIIRS, NOAA-20)

NOAA-20 VIIRS Level-2 Regional Ocean Color (OC) - Near Real-time (NRT) Data, version 2022.0
ocean NASA OB_CLOUD Level 2 active netCDF-4
In plain English

What it measures. Records the color of the ocean as seen from space and turns it into useful numbers, including how much chlorophyll (a stand-in for the amount of tiny floating plants called phytoplankton) is in the surface water, how clear the water is, and how much sunlight plants there can use. It also tracks haze in the air over the water.

How it's made. Built from the VIIRS sensor on the NOAA-20 satellite, with the raw light measurements cleaned up to remove the atmosphere's effect; this is a fast 'near real-time' version, so the calibration is good enough rather than the very best.

How & where you'd use it. Helps people watch algae blooms, ocean health, and ocean productivity as they happen. Because it is the quick-turnaround version, it is best for timely monitoring rather than long-term scientific records.

What's measured

Oceans › Ocean Optics › Ocean ColorOceans › Ocean Optics › ReflectanceAtmosphere › Aerosols › Aerosol Optical Depth/ThicknessAtmosphere › Aerosols › Aerosol Optical Depth/Thickness › Angstrom ExponentOceans › Ocean Optics › Chlorophyll › Chlorophyll ConcentrationOceans › Ocean Optics › Attenuation/TransmissionOceans › Ocean Chemistry › Organic CarbonOceans › Ocean Chemistry › Inorganic CarbonOceans › Ocean Optics › FluorescenceOceans › Ocean Optics › Photosynthetically Active Radiation

Coverage & cadence

  • Time span2017-11-29 → ongoing
  • Measured byNOAA-20 (VIIRS)
  • Processing levelLevel 2
  • 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 Ocean Color (OC) data suite provides calibrated, atmospherically corrected ocean-optics measurements and derived biogeophysical products. This data suite includes the Apparent Optical Properties (AOP) and provides satellite-derived measures of the interaction between solar radiation and the upper ocean. AOPs are “apparent” because they depend not only on the inherent optical properties (IOPs) of seawater and its constituents but also on the ambient light field. These variables are critical for studying light penetration, primary productivity, and biogeochemical cycling. Geophysical variables in this suite include: - Kd_490 - Diffuse attenuation coefficient at 490 nm, KD2 algorithm (m⁻¹) - Rrs - Remote sensing reflectance (sr⁻¹) - angstrom - Aerosol Angstrom exponent, 443 to 865 nm - chlor_a - Chlorophyll Concentration, OCI Algorithm (mg m⁻³) - l2_flags - Level-2 Processing Flags - aot_868 - Aerosol optical thickness at 868 nm - par - Photosynthetically Available Radiation, R. Frouin (einstein m⁻² day^⁻¹) - pic - Calcite Concentration, Balch and Gordon (mol m⁻³) - poc - Particulate Organic Carbon, D. Stramski, 2007 (443/555 version) (mg m⁻³)

Get the data

viirsj1_l2_oc_nrt_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="VIIRSJ1_L2_OC_NRT",
    version="2022.0",
    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.