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... > Instruments > Earth Remote Sensing Instruments > Passive Remote Sensing > Spectrometers/Radiometers > Imaging Spectrometers/Radiometers > Sentinel-3 MWR

Preferred term

Sentinel-3 MWR  

Definition

  • MWR is a nadir looking sounder, operating at 23.8 and 36.5 GHz (K/Ka-band) covering a bandwidth of 200 MHz in each channel. The objective is to provide water vapor and cloud water contents in the field of view of the altimeter, necessary to compensate for the propagation delay induced by these atmospheric components and affecting the radar measurements. Such corrections are only possible over the ocean, where the background noise is stable and can be quantified either by the 3rd (optional) radiometer channel, or derived from the altimeter measurements of the backscattered power. Alternatively, over ice and land surfaces where MWR data cannot be used, wet troposphere corrections will be derived based on global meteorological data and dedicated models. The MWR instrument is being developed by EADS CASA Espacio (ECE) under contract with Thales Alenia Space France (TAS-F) and ESA. MWR measures the thermal radiation emitted by Earth (brightness temperature). The received signal is proportional to the abundance of the atmospheric component emitted at the observed frequency and the sea-surface reflectivity. This information reveals the delay added to the altimeter pulses by moisture in the troposphere. The MWR instrument is comprised of the following part elements: antenna assembly, REU (Radiometer Electronics Units), the main structure and the thermal control hardware. Both K-band and Ka-band channels are fully redundant, except for the antenna assembly, with cold redundancy without cross-strapping. Center frequency, bandwidth 23.8 GHz, 200 MHz 36.5 GHz, 200 MHz Center frequency stability 180 kHz/ºC 220 kHz/ºC Radiometric performance Accuracy: < 3K Sensitivity: 0.29 K Stability: < 0.6 K Accuracy: < 3K Sensitivity: 0.34 K Stability: < 0.6 K Beam efficiency (2.5 HPBW) 94.1% 96.0% Antenna footprint diameter (average HPBW) 23.5 km 18.5 km Calibration cycle ~ 1 / hour Dicke frequency 78.5 Hz (nominal, programmable within 76-80 Hz range) Integration time 152.88 ms (nominal, within 150-157.9 ms range) Dynamic range 2.7 K to 320 K (radiometric performance guaranteed at 150 K - 313 K range) Side-lobe level (SLL) < -36 dB < -45 dB Antenna beam pointing Along-track: 1.98 Cross-track: 0.0º Along-track: 1.93º Cross-track: 0.0ºº Main antenna diameter 60 cm Instrument mass, power consumption ~25 kg, 34 W (en)

Broader concept

Change note

  • 2018-07-10 13:00:28.0 [mmorahan] Insert Concept add broader relation (Sentinel-3 MWR [d81fc4e3-c0b4-4205-82b2-ef2161c169a3,367815] - Imaging Spectrometers/Radiometers [944b7691-af37-4fb4-9393-c114e7997829,347979]);
  • 2018-07-10 13:18:33.0 [mmorahan] insert AltLabel (id: null category: primary text: Sentinel-3 Microwave Radiometer language code: en); insert Definition (id: null text: MWR is a nadir looking sounder, operating at 23.8 and 36.5 GHz (K/Ka-band) covering a bandwidth of 200 MHz in each channel. The objective is to provide water vapor and cloud water contents in the field of view of the altimeter, necessary to compensate for the propagation delay induced by these atmospheric components and affecting the radar measurements. Such corrections are only possible over the ocean, where the background noise is stable and can be quantified either by the 3rd (optional) radiometer channel, or derived from the altimeter measurements of the backscattered power. Alternatively, over ice and land surfaces where MWR data cannot be used, wet troposphere corrections will be derived based on global meteorological data and dedicated models. The MWR instrument is being developed by EADS CASA Espacio (ECE) under contract with Thales Alenia Space France (TAS-F) and ESA. MWR measures the thermal radiation emitted by Earth (brightness temperature). The received signal is proportional to the abundance of the atmospheric component emitted at the observed frequency and the sea-surface reflectivity. This information reveals the delay added to the altimeter pulses by moisture in the troposphere. The MWR instrument is comprised of the following part elements: antenna assembly, REU (Radiometer Electronics Units), the main structure and the thermal control hardware. Both K-band and Ka-band channels are fully redundant, except for the antenna assembly, with cold redundancy without cross-strapping. Center frequency, bandwidth 23.8 GHz, 200 MHz 36.5 GHz, 200 MHz Center frequency stability 180 kHz/ºC 220 kHz/ºC Radiometric performance Accuracy: < 3K Sensitivity: 0.29 K Stability: < 0.6 K Accuracy: < 3K Sensitivity: 0.34 K Stability: < 0.6 K Beam efficiency (2.5 HPBW) 94.1% 96.0% Antenna footprint diameter (average HPBW) 23.5 km 18.5 km Calibration cycle ~ 1 / hour Dicke frequency 78.5 Hz (nominal, programmable within 76-80 Hz range) Integration time 152.88 ms (nominal, within 150-157.9 ms range) Dynamic range 2.7 K to 320 K (radiometric performance guaranteed at 150 K - 313 K range) Side-lobe level (SLL) < -36 dB < -45 dB Antenna beam pointing Along-track: 1.98 Cross-track: 0.0º Along-track: 1.93º Cross-track: 0.0ºº Main antenna diameter 60 cm Instrument mass, power consumption ~25 kg, 34 W language code: en);
  • 2019-02-22 14:28:35.0 [mmorahan] insert WeightedRelation (id: null related concept uuid: 5449d87b-5573-450f-8acb-2fdfeab3c8ce relationship type: null relationship value: null generated by: null);
  • 2019-03-26 16:54:29.0 [sritz] insert WeightedRelation (id: null related concept uuid: 41163801-6aac-43e5-aed7-9f52613a6a73 relationship type: null relationship value: null generated by: null);
  • 2019-03-26 16:55:00.0 [sritz] update WeightedRelation (Platform-Instrument); update WeightedRelation (1);

URI

https://gcmd.earthdata.nasa.gov/kms/concept/d81fc4e3-c0b4-4205-82b2-ef2161c169a3

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