Height measurements of nightglow structures observed by all-sky imagers

To determine altitudes of nightglow wave structures, we have carried out simultaneous observations of OH Meinel bands and OI 557.7-nm emissions using four all-sky CCD imagers at two separated site. Two imagers were set up at the Shigaraki MU Observatory (34.85 degrees N, 136.11 degrees E), and two others were set up at the Muroh Observatory (34.57 degrees N, 136.01 degrees E). The range between the two sites is about 32 km. Observations were conducted during the new moon period from 21 January to 3 February 1998 as a part of the Planetary Scale Mesopause Observing System (PSMOS) campaign in Japan. On the night of 24-25 January, 1998, two orthogonal wave structures were observed at both sites. To determine the altitudes of nightglow structures, we use a new technique which is an application of a triangulation method. From the obtained images, we succeeded to derived a distribution of the altitudes differing by as much as 10 km across the field of view apparently in association with a large scale intensity variation. (C) 1999 COSPAR. Published by Elsevier Science Ltd.