著書

We describe a mobile vehicle lidar that enables near-range observations to achieve continuous monitoring of atmospheric aerosols with high spatiotemporal resolutions. The lidar employed a short-pulse laser of 355-nm wavelength. After passing the beam expander, the outgoing laser energy satisfied the eye-safety requirements, and the laser suspended the emission when detecting an overpass structure in the vehicle’s travel direction. The near-range observation was implemented by slanting a part of the receiving optical axis by placing several wedge prisms in front of the receiver telescope. Normally, lidar observations were made in the vertical direction while driving the vehicle at speeds slower than 50 km/h. Two additional mirrors installed above the car’s sunroof changed the directions of the laser beam and telescope field-of-view to achieve horizontal observation, if necessary. We demonstrated the capability of the proposed lidar system in detecting near-surface aerosol along a travel path of 25 km in the Tokyo Bay area, with an altitude range coverage between 7 and 650 m. Higher boundary layer heights with more significant aerosol loading were found in inland areas than over the coastal streets. Also, we observed aerosols over a rice paddy field of 600 m × 600 m by employing the horizontal observation mode.