THE CEOS DATABASE : Missions, Instruments and Measurements
CEOS EO HANDBOOK – MEASUREMENTS
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Radiation budget


The Earth’s radiation budget is the balance within the climate system between the energy that reaches the Earth from the Sun and the energy that returns from Earth to space. The goal of such measurements is to determine the amount of energy emitted and reflected by the Earth. This is necessary to understand the processes by which the atmosphere, land and oceans transfer energy to achieve global radiative equilibrium, which in turn is necessary to simulate and predict climate.
Detailed MeasurementDescription*InstrumentsTimeline
Diffuse attenuation coefficient (DAC)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 ].3 instruments
Downwelling (Incoming) long-wave radiation at the Earth surfaceFlux of long-wave radiation from sun, atmosphere and clouds to the Earth’s surface - Physical unit: [ W/m2 ] - Accuracy unit: [ W/m2 ].11 instruments
Downwelling (Incoming) short-wave radiation at the Earth surfaceFlux of short-wave radiation from sun, atmosphere and clouds to the Earth’s surface - Physical unit: [ W/m2 ] - Accuracy unit: [ W/m2 ].7 instruments
Downwelling (Incoming) solar radiation at TOAFlux of the solar radiation at the top of the atmosphere - Physical unit: [ W/m2 ] - Accuracy unit: [ W/m2 ].14 instruments
Long-wave cloud emissivityFraction of emitted radiation in respect of a black-body at the same temperature as the cloud top. Varies with wave-length. [Unit of measurement -dimensionless]0 instruments
Long-wave Earth surface emissivityEmissivity of the Earth’s surface in the thermal IR, function of the wavelength - Physical unit: [ % ] - Accuracy unit: [ % ].16 instruments
Short-wave cloud reflectanceReflectance of the solar radiation from clouds - Physical unit: [ % ] - Accuracy unit: [ % ].2 instruments
Short-wave Earth surface bi-directional reflectanceReflectance of the Earth’s surface function of the viewing angle and the illumination conditions in the range 0.4-0.7 µm (or other specific short-wave ranges) - Physical unit: [ % ] - Accuracy unit: [ % ].18 instruments
Solar spectral irradiance-0 instruments
Upwelling (Outgoing) long-wave radiation at Earth surfaceFlux of thermal radiation from the Earth’s surface - Physical unit: [ W/m2 ] - Accuracy unit: [ W/m2 ].6 instruments
Upwelling (Outgoing) long-wave radiation at TOAFlux of the terrestrial radiation in the range 4-200 µm (thermal emission) moving to Space through the top of the atmosphere - Physical unit: [ W/m2 ] - Accuracy unit: [ W/m2 ].22 instruments
Upwelling (Outgoing) short-wave radiation at the Earth surface-0 instruments
Upwelling (Outgoing) short-wave radiation at TOAFlux of the terrestrial radiation in the range 0.2-4 µm (reflected solar radiation) moving to Space through the top of the atmosphere - Physical unit: [ W/m2 ] - Accuracy unit: [ W/m2 ].13 instruments
Upwelling (Outgoing) spectral radiance at TOALevel-1 product. Spectral range 0.2-200 mm. Resolving power l/∆l = 1000. Accuracy quoted as SNR (Signal-to-Noise-Ratio), actually SNR-1 so that smaller figure means better performance, as usual. WMO and IOCCG quote accuracy in [ % ]1 instrument
* Description adapted from WMO.
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