Light Attenuation Kd490

This dataset represents monthly and annual mean summaries for Kd490 for the time period from 2000/2001 to 2017/2018, depending on the month and data available (see processing steps). Kd (490) is the diffuse attenuation coefficient at 490 nm. The diffuse attenuation coefficient in water indicates how strongly light intensity at a specified wavelength is attenuated within the water column. This parameter has wide applicability in ocean optics, as it is directly related to the presence of scattering particles in the water column, either organic or inorganic, and thus is an indication of water clarity. The diffuse attenuation coefficient at 490 nm (Kd490) indicates the turbidity of the water column -- how visible light in the blue to green region of the spectrum penetrates within the water column. The value of Kd490 (m-1) represents the rate at which light at 490 nm is attenuated with depth. For example, a Kd490 of 0.1/meter means that light intensity will be reduced one natural log within 10 meters of water. Thus, for a Kd490 of 0.1, one attenuation length is 10 meters. Higher Kd490 value means smaller attenuation depth and lower clarity of ocean water.

To support ocean planning activities pursuant to the Executive Order Regarding the Ocean Policy to Advance the Economic, Security, and Environmental Interests of the United States, the Energy Policy Act, the National Environmental Policy Act, the Rivers and Harbors Act, and the Coastal Zone Management Act.

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For coastal and ocean planning

Version 6.2 (Build 9200) ; Esri ArcGIS 10.5.1.7333

The attributes in this dataset are believed to be accurate.

Maximum scale of intended use is 1:80,000.

Spatial and attribute properties are believed to be complete, although attribute information has been simplified. Geometric thresholds from original data are preserved. No tests have been completed for exhaustiveness.

These data are believed to be logically consistent. Geometry is topologically clean.