Global Ocean Apparent Visible Wavelength Data from VIIRS

Apparent Visible Wavelength (AVW) data quantifies the spectral center of water-leaving reflectance across the global ocean, reported in nanometers. The dataset is produced by the OB_CLOUD organization from NOAA-20 VIIRS satellite observations for version 2022.0. It serves as an indicator for water type, with lower values for clear blue waters and higher values for greener, more productive or sediment-rich waters.

Use Cases

• Classify global ocean water types (e.g., oligotrophic vs. productive) based on the `avw` value.
• Guide chlorophyll-a algorithm selection or blending by using `avw` as a contextual spectral index.
• Detect regional temporal changes in water optical properties by analyzing time-series of the `avw` geophysical variable.
• Correlate `avw` with other ocean color products like chlor_a or Kd_490 to study coastal optical complexity.

Strengths

• Derived from the VIIRS instrument on the NOAA-20 satellite, a primary source for global ocean color data.
• Provides a single, standardized geophysical variable (`avw`) for summarizing the visible reflectance spectrum.

Limitations

• Interpretation of the `avw` variable can be ambiguous in optically complex coastal and inland waters.
• Data quality is contingent on ancillary quality flags for cloud, glint, and aerosol, which are not detailed here.

Provenance

Source

NOAA-20 VIIRS satellite sensor, processed by OB_CLOUD.

Collection Method

Satellite remote sensing, with the AVW metric calculated from water-leaving reflectance spectra (Rrs).

Time Range

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Freshness

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Geography

Global ocean coverage.