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Description

The Apparent Visible Wavelength (AVW) data suite quantifies the spectral “center” of ocean color by summarizing the shape of the water‐leaving reflectance spectrum (Rrs) across the visible. Reported in nanometers (nm), AVW is lower for bluer, clearer (oligotrophic) waters and higher for greener/browner, more optically complex or productive waters influenced by phytoplankton, colored dissolved organic matter (CDOM), or suspended sediments. Users apply AVW for water-type classification, algorithm selection/blending (e.g., guiding chlorophyll retrievals), regional change detection, and as context alongside chlor_a, Kd, IOPs, and PAR. As with all ocean-color products, review quality flags (cloud/glint/aerosol) and note that interpretations can vary in optically complex coastal/inland waters.

Geophysical variables in this suite include:
• avw — Apparent Visible Wavelength (nm)

Version Description

Reprocessing of Ocean Color (OC) Datasets

Product Summary

Platforms
NOAA-21
Instruments
VIIRS
Spatial Extent

N: 90 S: -90 E: 180 W: -180

Geographic Region
GLOBAL OCEAN
Coordinate System
CARTESIAN
Granule Spatial Representation
CARTESIAN
Temporal Extent
2022-11-10 to Present
Data Partner
Ocean Biology Processing Group (OBPG) ,
Ocean Biology Distributed Active Archive Center (OB.DAAC), Global Change Data Center, Earth Sciences Division, Science and Exploration Directorate, Goddard Space Flight Center, NASA (NASA/GSFC/SED/ESD/GCDC/OB.DAAC)
Concept ID
C3779579842-OB_CLOUD
Data State
ACTIVE
Number of Files/Granules
1161
Processing Level
4
Published
Updated
Science Keywords
Visible Wavelengths

Citation

Citation is critically important for dataset documentation and discovery. This dataset is openly shared, without restriction, in accordance with the EOSDIS Data Use and Citation Guidance.

Copy Citation

NASA Ocean Biology Processing Group. (2025). NOAA-21 VIIRS Level-4 Global Mapped Apparent Visible Wavelength (AVW) Data, version 2025.0 [Data set]. NASA Ocean Biology Distributed Active Archive Center. https://doi.org/10.5067/NOAA-21/VIIRS/L4M/AVW/2025.0 Date Accessed: 2025-12-13

Documents

Variables

Variables are a set of physical properties whose values determine the characteristics or behavior of something. For example, temperature and pressure are variables of the atmosphere. Parameters and variables can be used interchangeably. Variable level attributes provide individual information for each variable.

The Name in this table is the variable name. Fill value indicates missing or undefined data points in a variable. Valid range is the range of values the variable can store. Scale factor is used to increase or decrease the size of an object and can be used to correct for distortion. For questions on a specific variable, please use the Earthdata Forum.

Name Description Units Data Type Fill Value Valid Range Scale Factor
avw Apparent Visible Wavelength nm float32 -32767 400 to 700 N/A
lat Latitude degrees_north float32 -999 -90 to 90 N/A
lon Longitude degrees_east float32 -999 -180 to 180 N/A
palette palette N/A uint8 N/A N/A N/A
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