A mid-IR OPO based lidar system for DIAL measurements of tropospheric methane concentration

Summary form only given. Methane is an important greenhouse gas because it is a source gas that affects the lifetime of many other trace gases, its oxidation by OH produces peroxy radicals that are important for O/sub 3/ production, and its oxidation is important for the production, destruction, and recycling of HO/sub x/ radicals. The authors demonstrate a differential absorption lidar (DIAL) technique that measures the backscattered pulse energies at two wavelengths, /spl lambda//sub on/ and /spl lambda//sub off/. A comparison is made between the scattered signal monitored when the wavelength (/spl lambda//sub on/) of the laser is tuned to the peak of an absorption line of the molecule being investigated and when it (/spl lambda//sub off/) is detuned to lie in the wing of the line.