Analysis of lidar systems for profiling aurorally excited molecular species

We report a detailed analysis of lidar systems that profile aurorally excited molecular species in the upper mesosphere and lower thermosphere ([similar to]80-300 km). Current profiling of this region is performed with incoherent scatter radars that determine the total electron and ion concentrations but not the individual species. Studies of the aeronomy of the thermosphere requires knowledge of the species present and their relative populations in the different vibrational and rotational states. We review the spectroscopy of nitrogen to determine an optimized lidar system. We combine these results with current auroral observations and models to determine the performance of an actual lidar system. The study shows that such systems can provide high-resolution (1 km, 100 s) measurements of these species with current laser technology. Key words: Lidar, aurora, thermosphere, molecular spectroscopy, laser fluorescence.