The direct solar radiation observed by instruments aboard the ground-based solar tracking devices, is needed to estimate aerosol optical thickness. However, the instruments on unstable platforms such as ship sometimes don't accurately point the sun. In our research, the PAR radiometer that can observe direct solar radiation with high stability has been developed. The shadow band of the PAR radiometer assists to obtain stable observation data on any unstable platform. Actually the newer-developed PAR radiometer doesn't need tracking the sun anymore. We have also developed an algorithm that retrieves aerosol optical thickness from the PAR radiometer data. From the experiments performed from 2006 to 2008, aerosol optical thicknesses were estimated with high accuracy.
SELENE (KAGUYA) is a Japanese lunar polar orbiter that was launched from Tanegashima Space Center on September 14, 2007, onboard the 13th H-IIA launch vehicle. The Lunar Imager/SpectroMeter (LISM) developed for SELENE consists of three subsystems : the Multiband Imager (MI), Terrain Camera (TC), and Spectral Profiler (SP). MI can obtain entire lunar surface multispectral imagery of the highest spatial resolution that has ever been reached. It is a push-broom imager consisting of a visible sensor (MI-VIS) and a near-infrared sensor (MI-NIR) and has nine spectral bands, from visible to near-infrared wavelengths. The spatial resolution of MI-VIS is 20m, and that of MI-NIR is 62m at an orbital altitude of 100km. Each observation band of MI has parallax between it and all the others, due to its instrument structure. Therefore, in order to obtain sufficient accuracy of inter-band registration, we must correct geometric distortions caused by the topographic effect. However, it is possible to carry out stereo 3D measurement using the inter-band parallaxes. We developed a rigorous, high-speed method to transform a digital image arbitrarily, given local area matching on a pixel-to-pixel basis. It has thus become possible to improve the accuracy of the lunar geological investigation by MI inter-band stereo 3D measurement and topographic correction of multiband images. With the local area matching method, we devised several algorithmic innovations. In this paper, we describe the geometric correction methods for MI, the geometric accuracy verification results using CG images prior to the launch of SELENE (KAGUYA), and the early analysis results of actually observed MI data regarding geometric correction.
The EOS-Aqua Advanced Microwave Scanning Radiometer (AMSR-E) has been providing global sea surface temperature (SST) data continuously under day/night and almost all weather conditions from June 2002 to the present. AMSR-E data are valuable for monitoring SST changes in the global oceans, including the Arctic Ocean, because of unique coverage during cloudy conditions. Comparative analysis in the Arctic Ocean shows that the AMSR-E SSTs are consistent with those from infrared and buoy data. Results of analysis of the AMSR-E data show anomalously high SST values in ice-free areas of the Arctic Ocean in summer especially in the Chukchi Sea in 2007. An unusually rapid increase of 5°C in SST over a period of seven days was observed which is consistent with the rapid decline in the sea ice cover in the region in 2007 that led to a dramatic decline and record low perennial ice cover in the Arctic during the same year.