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Instrumental details
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AMSOS is a passive microwave radiometer operating at 183GHz for water vapor
respectively at 175GHz for ozone measurements. The signal is downconverted by
a local oscillator at 179.6GHz to
an intermidate frequency (IF) of 3.7GHz. Sideband supression is realized by a
Martin-Pupplett Interferometer (MPI).
The IF is splitten up and downconverted again to the input frequencies of the
several attached spectrometers.
Calibration is done by two loads hot and cold. The first is at ambient temperature,
the latter cooled down to boiling temperature of liquid nitrogen.
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Table: AMSOS instrumental details
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Observation frequencies:
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183.3GHz±0.5GHz (H2O) and 175.9GHz±0.5GHz (O3)
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Intermediate frequency:
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3.7GHz
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Sideband supression:
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Martin-Puplett Interferometer with possibility to switch on the fly from upper
(183GHz) to lower (176GHz) sideband.
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Quasioptics:
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- Corrugated horn (radiometer output HPBW=1deg)
- Parabolic mirror
- Martin-Puplett-Interferometer (sideband filter)
- λ/4-Isolator at 183GHz (baseline suppression)
- Elliptic mirror
- Microwave transparent aircraft window
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Spectrometers:
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- Accousto optical broadband, bandwidth=1GHz, resolution 1MHz, manufacturer: Observatoire de Meudon. Shortname: AOS_F1
- Accousto optical narrowband, bandwidth=50MHz, resolution 75kHz, manufacturer: Elson research Inc. Shortname: AOS_E1
- Digital Fast Fourier Transform (FFT), bandwidth=1GHz, resolution 61kHz, manufacturer: Acqiris. Shortname: FFT_ACQ1
- Digital Fast Fourier Transform (FFT), bandwidth=1GHz, resolution 12kHz, manufacturer: BEAM ltd. Shortname: FFT_BEAM1
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Calibration technique:
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Hotload (ambient) - Coldload (LN2) calibration.
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Receiver noise temperature:
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2800K SSB
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Fig: Racks inside the aircraft.
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Fig: Learjet Arena Arctica in Kiruna.
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