Full catalog/MODISA_L3m_IOP
MODISA_L3m_IOP·v2022.0·dataset

How ocean water absorbs and scatters light (Aqua)

Aqua MODIS Level-3 Global Mapped Inherent Optical Properties (IOP) Data, version 2022.0
ocean NASA OB_CLOUD Level 3 active netCDF-4
In plain English

What it measures. Maps how ocean water and the particles in it absorb and scatter light (its 'inherent optical properties'), broken down into components from water itself, phytoplankton, and dissolved or detrital matter, with uncertainty estimates. These describe the water regardless of sun angle or viewing direction.

How it's made. Retrieved from MODIS reflectance measurements on the Aqua satellite using the GIOP model, delivered as global gridded maps (Level 3).

How & where you'd use it. Used to classify water types, assess water clarity, study ocean biology and chemistry, and compare results across different satellites more reliably than basic color products allow.

What's measured

Oceans › Ocean Optics › AbsorptionOceans › Ocean Optics › ScatteringOceans › Ocean Optics › GelbstoffBiosphere › Ecosystems › Aquatic Ecosystems › Plankton › Phytoplankton

Coverage & cadence

  • Time span2002-07-04 → ongoing
  • Measured byAqua (MODIS)
  • 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 Inherent Optical Properties (IOP) suite provides per-pixel inherent optical properties - quantities that describe how seawater and its constituents absorb and scatter light, independent of illumination or viewing geometry. IOPs are retrieved from spectral Remote Sensing Reflectance (Rrs) using the default configuration of the Generalized Inherent Optical Properties (GIOP) model framework. These products support water-type classification, water-clarity assessment, biogeochemical studies, and forward/adjoint radiative-transfer applications, and they enable more robust cross-sensor comparisons than purely apparent (AOP) products. Geophysical variables in this suite include: - a — Total absorption coefficient (sum of pure water + phytoplankton + CDOM/detritus, m⁻¹) - bb — Total backscattering coefficient (m⁻¹) - aph_443 — Phytoplankton absorption coefficient at 443 nm (m⁻¹) - aph_unc_443 — Uncertainty in absorption due to phytoplankton at 443 nm (m⁻¹) - adg_443 — Combined CDOM + non-algal detritus absorption coefficient at 443nm; accompanied by adg_s (spectral slope, units nm⁻¹). - adg_unc_443 — Uncertainty in absorption due to gelbstoff and detrital material at 443 nm (m⁻¹). - bbp_443 — Particulate backscattering coefficient at 443nm (m⁻¹); include bbp_s (power-law slope, unitless) describing spectral shape. - bbp_unc_443 — Uncertainty in particulate backscattering at 443 nm (m⁻¹). - rrsdiff — Fractional mean Rrs difference.

Get the data

modisa_l3m_iop_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="MODISA_L3m_IOP",
    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.