The terahertz radiometer for APSOS project at Yangbajing Observing Station

A dual-band SIS terahertz heterodyne spectrometer for Atmospheric Profiling Synthetic Observation System (APSOS) project has been designed and is now operating in Yangbajing Observing Station, Tibet. It aims at observing the spectral lines of greenhouse gas as well as monitoring the local atmospheric opacity at the frequency range of 180~380 GHz. The architecture of the spectrometer has been described in detail. The measured receiver system noise is less than 160K at 180~300GHz and less than 230K at 320~380GHz. The measurement theory and method of atmospheric opacity and spectral lines has been described, and ozone molecular spectral lines have been preliminary observed.