Title: 0I 630.0 nm Nightglow Depletion Observations at Watukosek, Indonesia
Abstract: We present the 0I 630.0 nm night airglow (nightglow) observation data obtained with a ground-based scanning photometer at Watukosek (7.6°S, 112.7°E), Indonesia. We made the first observation in December, 1986 in order to study ionospheric F region plasma behavior from the ground. The airglow pattern over equatorial anomaly region is closely related to the distribution of equatorial F region electron density. Plasma turbulence in ionospheric F layer can be reflected on space configurations for 0I 630.0 nm airglow emission; plasma bubbles are observed as structured depletion regions in nightglow intensity. During the second observation campaign of September 26, 27, and 28, 1989, we observed multiple depletion structures in intensity of 0I 630.0 nm nightglow moving eastward. We measured almost the same depletion feature at two directions, zenith and 30° north from the zenith. We suggest that we observed the nearly field-aligned depletion structures. In 1993 from May through November we made nightglow observations for 46 nights. However, we observed few distinct phenomena such as plasma bubbles. Plasma drift velocities derived from these measurements of nightglow depletion events are presented and briefly discussed.