Conclusion

In this article, we review the issues involved in the remote sensing of atmospheric gases, then present the fundamental equations describing the amount of signal received by a hard-target lidar on the one hand, and by a profiling atmospheric lidar on the other. We then gave an overview of the two main lidar gas measurement techniques: Raman lidar and DIAL lidar. For each technique, we outlined the underlying physics, and explained how the effects of Raman scattering and molecular absorption are exploited in lidar systems. We also presented an example of a lidar system and gas measurement (H ₂ and CH ₄ ) for each of these technologies. Finally, we have attempted to give some elements of comparative appreciation of Raman and DIAL lidar techniques.

There are still many challenges...