Real-time, wide field-of-view monitoring of the atmosphere by means of a novel imaging lidar system

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Atmospheric aerosols, in particular, tropospheric aerosols significantly impact the climate through the scattering of radiation and their behavior as the cloud-condensation nuclei. Their microscopic properties in the real atmosphere, however, have not been fully grasped from observations so far. The origin and transportation of extremely high-energy cosmic-ray particles are investigated in the All-sky Survey High Resolution Air-shower (Ashra) telescope project. A telescope array system for the whole hemisphere observation is currently deployed on the Hawaii Island USA Iron the present research project, we have combined this novel Ashra telescope with lidar technique in order to achieve the real-time monitoring of two-dimensional distributions of aerosols and clouds in the lower atmosphere. Although a transmitting laser system and receiving telescope system are collocated in conventional mono-static lidar observations, the highly sensitive nature of the Ashra telescope makes it possible to locate the transmitter and receiver systems separately. This bistatic approach has the advantage that the aerosol/cloud distribution near the surface level can be directly monitored in detail. If the laser beam is scanned while the detection field-of-view sector of the telescope is fixed, the density of target particles can be measured in the vicinity of the forward-scattering regime, where the scattered intensity is generally much higher than the conventional, back-scattering regime. Through this project, we have fully checked the basic performance of our imaging lidar system, and have demonstrated its capability in obtaining the atmospheric images in a two-dimensional way.