Nobuo Takeuchi, Gerry Bagtasa, Nofel Lagrosas, Hiroaki Kuze, Suekazu Naito, Makoto Wada, Akihiro Sone, Hirofumi Kan, Tatsuo Shiina
Advances in Geosciences: Volume 10: Atmospheric Science (AS) 99-114 2009年1月1日 査読有り
Continuous lidar observation of the atmosphere is important for monitoring various phenomena such as air pollution, local meteorology, and plume diffusion. Center for Environmental Remote Sensing (CEReS), Chiba University, developed a portable automatic lidar (PAL) with the cooperation of Hamamatsu Photonics Inc. After installing the automatic alignment capability, the PAL system has provided continuous observation data in every 20 s except for some maintenance periods. The lidar operates at 532 nm (second harmonic of Nd:YAG laser), with 1.4 kHz pulse-repetition frequency, 50 ns pulse width, and 15 μJ pulse energy. The signal is received by a 20-cm diameter telescope pointed northward with an elevation angle of 38°, and processed by a photon counter. The range resolution is 24m (height resolution is 15m). During the operation period of 3 years, we have observed atmospheric oscillations of Brunt-Vaisala type with oscillation periods of several to several 10 minutes, raindrops yielding information on falling speeds and corresponding droplet sizes, upward/downward motion of air in the boundary layer, and statistics on the cloud bottom height. In this chapter, we describe various features of PAL data that characterize meteorological phenomena, including precipitation, frontal passage, and development of boundary layer.