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Radiometer
OSTM/Jason-2
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The Advanced Microwave Radiometer (AMR), is an enhanced version of the Jason-1 Microwave Radiometer (JMR). Like the JMR, it acquires measurements via three separate frequency channels to determine the path delay of the altimeter's radar caused by atmospheric water vapor. This instrument measures radiation from Earth's surface at three frequencies (18, 21 and 37 GHz). Measurements acquired at each frequency are combined to determine atmospheric water vapor and liquid water content. Once the water content is known, we can determine the correction to be applied for radar signal path delays.
Additional information on the AMR is available on the AVISO site.
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Jason-1
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The JMR, Jason Microwave Radiometer, acquires measurements via three separate frequency channels to determine the path delay of the
altimeter's radar signal due to atmospheric water vapor.
Its measurements can also be used directly for studying other atmospheric
phenomena, particularly rain.
To determine atmospheric water vapor content accurately, we need to eliminate sea surface and cloud contributions
from the signal received by
the radiometer. That is why the JMR uses three different frequencies:
- Redundant 23.8GHz channel measures atmospheric water vapor emission
- 18.7 GHz Channel correct for ocean surface effects
- 34.0 GHz Channel corrects for non raining clouds
By combining measurements acquired at each of these frequencies, we can extract the water
vapor signal.
Additional information on the JMR is available on the AVISO site.
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TOPEX/Poseidon
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The TOPEX/Poseidon microwave
radiometer is a three-frequency
sensor used to estimate the atmospheric water vapor content
in the nadir column through which the altimeter
signal is traveling. Since water vapor distorts the altimeter's
reading, the water vapor content is measured to correct the
altimetry measurement. The sensor uses one frequency to make
the measurement, and two frequencies to remove the effects of
wind speed and cloud cover.
There is a backup receiver for the measurement frequency.
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Altimeter(s) |
Radiometer |
DORIS |
LRA |
GPS/TRSR
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