Upendra N. Singh¹, Grady J. Koch¹, Michael J. Kavaya¹, Syed Ismail¹

¹NASA Langley Research Center

2-micron lidar technology has been in use and under continued improvement for many years toward wind measurements. But the 2-micron wavelength region is also rich in absorption lines of CO₂ (and H₂O to a lesser extent) that can be exploited with the differential absorption lidar (DIAL) technique to make species concentration measurements. A coherent detection receiver offers the possibility of making combined wind and DIAL measurements with wind derived from frequency shift of the backscatter spectrum and species concentration derived from power of the backscatter spectrum. A combined wind and CO₂ measurement capability is of interest for applications on both Earth and Mars. CO₂ measurements in the Earth atmosphere are of importance to studies of the global carbon cycle. Data on vertically-resolved CO₂ profiles over large geographical observations areas are of particular interest that could potentially be made by deploying a lidar on an aircraft or satellite. By combining CO₂ concentration with wind measurements an even more useful data product could be obtained in the calculation of CO₂ flux. A challenge to lidar in this application is that CO₂ concentration measurements must be made with a high level of precision and accuracy to better than 1%. Under NASA Laser Risk Reduction Program (LRRP), researchers at NASA Langley Research Center have developed 2-micron laser system that provides high pulse energy, narrow linewidth, tunable, wavelength-stabilized, and double-pulsed lasers that are quite suitable for simultaneous profiling of wind and carbon dioxide. Examples of wind and CO₂ measurements with the existing system will be presented along with the progress made towards developing the new system and its projected capability. Further developments are continuing toward the development of airborne and eventually space-borne wind and CO₂ profiling system. A discussion of these developments and the projected capabilities of these systems will also be presented in this paper.