Feasibility Study for an Airborne N2O Lidar

Kurzfassung

Nitrous oxide, N2O is the third most important anthropogenic greenhouse gas after carbon dioxide and methane. The major source is nitrogen fertilization in croplands. Differential absorption lidar is very demanding since suitable absorption lines exist only in the infrared, which challenges lidar transmitter and detector options. Spectroscopic investigations and lidar instrumental noise simulations show that in the 4.5 µm band a trough position between two strong N2O lines is likely the best option for an airborne lidar. A second option exists in the 3.9 µm band, at the cost of higher laser frequency stability constraints. Independently on the 3.9 versus 4.5 µm question an airborne lidar is expected to fulfill the N2O measurement requirements for regional gradient or hot spot detection with technically realizable and affordable transmitter (100 mW average laser power) and receiver (20 cm telescope) characteristics. However, such a system would benefit from progress in infrared transmitter and detector technology.