Development of very sensitive heterodyne spectrometer at millimeter and infrared wavelength for strato-mesospheric atomospheric minor components

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Ground-based microwave sensor are commonly used in remote sensing of trace constituents by passive sounding of rotational transition of key stratospheric molecules, such as ozone. This method has a distinctive advantage for measurements of diurnal and short term variations over other techniques.The microwave observations measure thermal emission of molecules and then measurement dose not require a background radiation source like the sun as is the case in absorption measurement.The observations does not also require a clear sky and measurements can be made throughout the day and the night.However, conventional ozone monitoring method do not enceble satisfactory realtime monitoring of concentration and altitude distribution.Accordingly we have developed a system using superconductor-insulator superconductor (SIS) mixer having the best noise characteristics reported to date.Summarizing observations obtained by our instrument, we may conclude as follows.1. Diurnal variations of the mixing ratio at various altitudes from 36 through 75 km appear in agreement with theoretical calculations and observations by many authors except night-time variations near the top of the mesosphere.2. The ozone mixing ratio about 70 km shows night-time variation variable from day to day with an amplitude of about 20% of the midnight value.Time variations of the mixing ratio just before the sunrise and after the sunset are obtained from observations with an integration time of 3 minutes