How ocean water absorbs and scatters light (Aqua)
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
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
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. Official links
- OPeNDAP Site for Aqua MODIS Standard Mapped Image (SMI) Product USE SERVICE API
- Earthdata Search allows users to search, discover, visualize, refine, and access NASA Earth Observation data. GET DATA
- View the version history of this product. VIEW RELATED INFORMATION
- NASA's Ocean Color Web - Data Distribution Site GET DATA
- Aqua Homepage VIEW RELATED INFORMATION
- MODIS Homepage VIEW RELATED INFORMATION
- Satellite data procesing can be difficult. We're here to help! Visit the Oceandata Help Hub to navigate learning content for accessing visualizing, and analyzing data products. VIEW RELATED INFORMATION
- Algorithm Theoretical Basis Document for Inherent Optical Properties (IOP) VIEW RELATED INFORMATION