Abstract

RIS (Retroreflector in Space) is one of the sensors of ADEOS (Advanced Earth Observing Satellite), a sun-synchronous polar-orbit satellite which was launched on August 17th of 1996¹). RIS is a corner-cube reflector for earth-satellite-earth laser long path absorption measurements of atmospheric trace species, such as O₃, CH₄, HNO₃, CO, and N₂O, etc.²) In this experiment, a laser beam is transmitted from a ground station to RIS and the reflected light is received at the ground station and absorption spectrum of the atmosphere is measured in the round-trip optical path. The wavelength of the reflected light varies due to the Doppler shift caused by the stellite movement. Because the magnitude of the Doppler shift depends on the satellite position relative to the ground station, we can measure the absorption spectra of the atmosphere with a high wavelength resolution. We developed the measurring system with two single-longitudinal-mode transverse, electric, atmospheric (TEA) CO₂ lasers³). One of the laser is used for measuring the absorption of the target molecule. The other is used for measuring the reference signals to compensate the atmospheric turbulence, variance of the transparency, and the angular denpendence of the reflectance of RIS. Vertical profiles of the atmospheric gas species can be retrieved by solving the inverse problem.⁴⁾ The analysis of the real return signal from RIS will be presented.

© 1997 Optical Society of America