It has been pointed out that globally hermatypic corals in coral reefs have been seriously damaged in recent years, and it
is predicted that such damages will expand in area in the future. It is important to monitor corals globally, in detail, and
over long-term periods, for preservation of the marine environment and biodiversity. The spot-check method, one of the
major coral monitoring methods, is operated by snorkelers or divers, and therefore, its operation is limited by the seastate,
and its monitoring areas are often for specific observation points. On the other hand, the satellite remote sensing,
another major coral monitoring methods, can cover composite coral reef areas, but the image resolution is a few meters,
and it is not possible to monitor small size coral colonies and deep sea areas.
The boat-based fluorescence imaging lidar system has been developed to complement these coral monitoring methods.
This system obtains linear coral observation data along the boat track, and makes it possible to build a cooperative coral
monitoring network. Since most hermatypic corals have fluorescent proteins, living tissues can be monitored using the
blue-to-green fluorescence from UV excitation. It is possible to observe the UV-excited fluorescence images from live
coral even in the daytime, by the UV excited fluorescence imaging lidar. Additionally, laser bathymetry is also possible
by time-of-flight measurement. We have succeeded in observing the pseudo-coral fluorescent images and depths down to
30 m depth at the testing basin. Secondly, we have succeeded in observing the live coral fluorescent images and their
depths by the lidar system using a glass-bottom-boat at Taketomi island, Okinawa, Japan. The system summary and
observed data are reported in this paper.
Space-borne Doppler lidar is expected to make wind profile observations on a global scale with an accuracy of 1 to 2 m/s. It may solve the problem of the shortage of the accuracy and distribution in the current wind data. We have studied an eye-safe coherent Doppler lidar (CDL) model that could be deployed on the exposed facilities of Japanese Experiment Module (JEM) and that would meet the science requirements. We have good prospects of 500mJ output at 10Hz in a conduction cooling sub-scale laser, which could be a small model of space-borne laser for JEM/CDL. We are making studies on improving the system’s efficiency, reducing its weight, and establishing the fundamental technologies involved. Research on another possibility, e.g. a free flyer, for a demonstration mission besides of JEM/CDL is also valuable to be considered. Development of algorithm for application of coherent lidar system is also in progress through air-borne experiments and ground-based observations.
Global wind profiling with a space-borne Doppler lidar is expected to bring big progress in the studies on global climate change and Numerical Weather Prediction. A feasibility study has been done for an eye-safe 2micron coherent Doppler lidar aiming at demonstration of the technology onboard the Japanese Experiment module of the International Space Station. We are now developing an airborne coherent Doppler lidar system to measure wind profile under a jet plane for simulation of the Doppler lidar measurement in space. This system is also operated in the ground to develop algorithm of the wind measurements and the results of the wind profiles are compared with those derived from other instruments.
An eyes-safe, airborne, coherent Doppler lidar (CDL) system has been developed at the Communications Research Laboratory (CRL). It consists of a 2-mm laser transmitter, a receiver, a heterodyne detector, a scanning device, and signal processing equipments. The main objective of the development of this CDL system is to demonstrate the feasibility of CDL from a moving platform. The second objective is to develop a computational algorithm for calculating wind velocity and wind direction. The performance of the CDL was evaluated by a ground-based experiment on wind profiling. That is, zonal, meridional, and vertical wind profiles were obtained by the CDL and by the velocity-azimuth display (VAD) technique with a height resolution of 150 m for every 20 minutes. These profiles were compared with the wind profiles measured by the WindProfiler (WP) installed at CRL. Although the temporal and vertical resolution measured by the CDL differed slightly from that by the WP, the calculated horizontal wind velocity measured by the CDL corresponded well with the WP calculations. It is thus concluded that the developed computational algorithm provides valid calculations of wind velocity.