IMOS - Satellite Remote Sensing - NOAA20 - 01 day - Diffuse attenuation coefficient (k490)

Hard coral cover and composition Ocean colour

The NOAA20 satellite platform carries a VIIRS sensor that observes sunlight reflected from within the ocean surface layer at multiple wavelengths. These multi-spectral measurements are used to infer the diffuse attenuation coefficient (Kd) at 490nm wavelength which provides information on how light is attenuated in the water column. It is defined as the scaling length of the exponential decrease of the downwelling irradiance, and has units (m^-1). The VIIRS K490 product estimates Kd at 490nm wavelength, using a semi-empirical model based on the ratio of water leaving radiances at 490nm and 555nm. The algorithm is described at https://oceancolor.gsfc.nasa.gov/atbd/kd/.

Data and resources

Link to OPENDAP server

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Satellite Remote Sensing page on IMOS website

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srs_oc_noaa20_K_490_url/K_490

SRS - K490 - WMS layer

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srs_oc_noaa20_K_490_url

The GoGoDuck subsets and aggregates gridded data. Data is returned as a NetCDF file.

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GoGoDuck help documentation

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Access To AWS Open Data Program registry for the Cloud Optimised version of this dataset

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Access to Jupyter notebook to query Cloud Optimised converted dataset

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Website of the Integrated Marine Observing System (IMOS)

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License Graphic

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Additional information

Temporal extent	2022-05-21 – ongoing
Date (creation)	2025-02-07
Status	onGoing
Update frequency	asNeeded
Metadata language	en
License	Data, products and services from IMOS are provided "as is" without any warranty as to fitness for a particular purpose.
Source metadata	ISO 19115 XML
Last updated	2026-11-05
Created	2026-11-05
API	package_show