Concept information
Preferred term
BBR
Definition
- BBR is an ESA multilook along-track instrument with a 10 km footprint (heritage of ScaRaB). The objective is to provide measurements of the reflected short-wave (SW channel, 0.25-4 µm) and the emitted long-wave (LW channel, 4.0-50 µm) radiance at the top of the atmosphere (TOA) along three along-track views (forward, nadir, and backward). The BBR has spectral channel and accuracy requirements typical for ERB (Earth Radiation Budget) instruments. 81) 82) 83) 84) 85) 86) The instrument is required to observe the incoming radiances in three different directions continuously – nadir, forward and backward. The forward and backward views cover the scene with an OZA (Observational Zenith Angle) of 55º, equivalent to an offset between the three telescopes of 50º. The optical design provides equal pixel sizes (10 km x 10 km) for all three views. There is no cross-track swath. Co-registration to 10% of the footprint size of all views is required. The instrument is a two-channel radiometer, in which the LW channel is obtained by subtracting the SW component from a channel covering the complete spectral range. Dedicated telescopes are used for all views. They are mounted together in one block, allowing them to be moved also towards an internal black body simulator and external views for calibration. A channel selector revolves around the telescopes to modulate the incoming flux (as the detectors are only sensitive to alternating signals), and to generate the two spectral channels. The scene measurements are over-sampled in all three views to correct scene altitude errors by post processing. The telescope assembly is moved in the across track direction by a mechanism to compensate the rotation of the Earth thereby ensuring co-registration of the three views. The importance of this measurement technique is that it provides data to drive the algorithm that converts the instrument-measured flux to the hemispherical TOA radiance. The BBR instrument is being designed and developed by a UK-led consortium with SEA (Systems Engineering & Assessment Ltd.) as the prime contractor, with RAL (Rutherford Appleton Laboratory) responsible for the BBR optics unit, Sula Systems Ltd., ESR Electronic Components Ltd., INO of Canada, SciSys, and LMD (Laboratoire de Météorologie Dynamique du CNRS.) of France. (en)
Broader concept
- Radiometers (en)
Change note
- 2018-07-04 10:36:24.0 [mmorahan] Insert Concept add broader relation (BBR [f3c9a235-939d-4898-94f3-3dea5ad187e1,367747] - Radiometers [5b753e40-b3f1-426a-8d92-ffee1d675468,347283]);
- 2018-07-04 10:38:30.0 [mmorahan] insert AltLabel (id: null category: primary text: Broadband Radiometer language code: en); insert Definition (id: null text: BBR is an ESA multilook along-track instrument with a 10 km footprint (heritage of ScaRaB). The objective is to provide measurements of the reflected short-wave (SW channel, 0.25-4 µm) and the emitted long-wave (LW channel, 4.0-50 µm) radiance at the top of the atmosphere (TOA) along three along-track views (forward, nadir, and backward). The BBR has spectral channel and accuracy requirements typical for ERB (Earth Radiation Budget) instruments. 81) 82) 83) 84) 85) 86) The instrument is required to observe the incoming radiances in three different directions continuously – nadir, forward and backward. The forward and backward views cover the scene with an OZA (Observational Zenith Angle) of 55º, equivalent to an offset between the three telescopes of 50º. The optical design provides equal pixel sizes (10 km x 10 km) for all three views. There is no cross-track swath. Co-registration to 10% of the footprint size of all views is required. The instrument is a two-channel radiometer, in which the LW channel is obtained by subtracting the SW component from a channel covering the complete spectral range. Dedicated telescopes are used for all views. They are mounted together in one block, allowing them to be moved also towards an internal black body simulator and external views for calibration. A channel selector revolves around the telescopes to modulate the incoming flux (as the detectors are only sensitive to alternating signals), and to generate the two spectral channels. The scene measurements are over-sampled in all three views to correct scene altitude errors by post processing. The telescope assembly is moved in the across track direction by a mechanism to compensate the rotation of the Earth thereby ensuring co-registration of the three views. The importance of this measurement technique is that it provides data to drive the algorithm that converts the instrument-measured flux to the hemispherical TOA radiance. The BBR instrument is being designed and developed by a UK-led consortium with SEA (Systems Engineering & Assessment Ltd.) as the prime contractor, with RAL (Rutherford Appleton Laboratory) responsible for the BBR optics unit, Sula Systems Ltd., ESR Electronic Components Ltd., INO of Canada, SciSys, and LMD (Laboratoire de Météorologie Dynamique du CNRS.) of France. language code: en);
- 2019-02-15 12:37:31.0 [mmorahan] insert WeightedRelation (id: null related concept uuid: bf66ef8c-acc5-4c2f-b519-db0cbee37c99 relationship type: null relationship value: null generated by: null);
URI
https://gcmd.earthdata.nasa.gov/kms/concept/f3c9a235-939d-4898-94f3-3dea5ad187e1
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