CEOS EO HANDBOOK – MEASUREMENT INSTRUMENTS
Measurements > Atmosphere >
Radiation budget >
Diffuse attenuation coefficient (DAC)


Measurement Definition*: Former name: “Water clarity”. Parameter extracted from ocean colour observation. Indicative of water turbidity and vertical processes in the ocean. Requested in both open ocean and coastal zone - Physical unit: [ m-1 ] - Accuracy unit: [m-1 ].
InstrumentStatus/
Accuracy
Instrument DescriptionMeasurement TechnologyTimeline
MODIS
MODerate-Resolution Imaging Spectroradiometer
Operational
Data on biological and physical processes on the surface of the Earth and in the lower atmosphere, and on global dynamics. Surface temperatures of land and ocean, chlorophyll fluorescence, land cover measurements, cloud cover (day and night).n/a
OCI
Ocean Color Instrument
Operational
Ocean color slit-grating imaging spectrometer/radiometer for measuring top of atmosphere reflectance which is used to estimate ocean leaving light that contains information on biological components plus aerosol and cloud propertiesln/a
OLCI
Ocean and Land Colour Imager
Operational
Marine and land services.n/a
VIS-NIR
Multi-spectral Optical Camera - Visible & Near Infrared
Approved
Ocean Colour - Open ocean, coastal & in-land waters.n/a
* Description adapted from WMO.