We have developed an air-borne ultraviolet remote sensor, named "Airborne-OPUS." It is a nadir-looking hyper spectral imaging spectrograph, with 1100 spectral channels and 330 spatial channels. It covers the wavelength range of 190-455 nm with 0.34 nm sampling step and covers 15 degrees field of view. All main components of the sensor are composed of commercially available products : a Jobin-Yvon spectrograph as a disperser, a PixelVision 1100×330 CCD camera as a detector, and a ready-made single lens as its front-end optics. For the data calibration, we examined the basic parameters and the performance characteristics of the detector, such as read noise, dark current, linearity, and pixel-response uniformity.
After two-demonstration flights using the Gulfstream-II aircraft, the performances of Airborne-OPUS, such as spectral resolution, signal-to-noise ratio, have been evaluated. In the flights around Miyake-jima and Sakura-jima volcanoes, the absorption structure of SO2 was detected in the observed spectra, using the DOAS technique. The vertical column amount of SO2 was derived from each data, and its horizontal distribution was revealed. The sensitivity of the sensor was also examined, and we discussed its application to the detection of urban pollutions.
