Performance predictions for a mid-IR lidar suitable for measuring N2O in the boundary layer

Nitrous oxide is a radiatively active gas with 300 times the greenhouse warming potential of CO2. Its budget is not well understood; however it is known that its sources are at the surface, primarily microbial activity but also biomass burning, transportation, and industrial processes. Here we model the capability of differential absorption lidar (DIAL) for measuring emissions of N2O from area sources using an end-to-end model of a DIAL with achievable system parameters. The model includes inversion of synthetic lidar signals with random noise and a Monte Carlo approach is used to assess expected errors. As a part of the modeling we identify several absorption lines around 4 μm with an eye to their differential cross sections (using nearby offline positions), temperature sensitivity, and presence of possible interfering species. We use the end-to-end model to determine sensitivity and range and time resolutions in realistic scenarios.