Mentor: Vincent Wickwar
Rayleigh LIDAR (LIght Detection And Ranging) Used to Explore the Mesosphere
The most visible lidar in the Atmospheric Lidar Observatory (ALO), located in the SER building, is a powerful Rayleigh-scatter lidar. A big Nd:YAG laser emits pulses of green light that are scattered off atmospheric molecules. From the return signal, profiles of relative density and absolute temperature are derived from the mesosphere between 45 and 90 km.
Eleven years of good data have been acquired. They have been analyzed for relative densities and temperatures; noctilucent clouds; thin layers; occurrence of gravity waves; wave potential energy; occurrence of convective instabilities; trends; and solar-cycle response. These provide background, inspiration, and inputs for a number of future analyses. The software used is IDL, which is very common in the atmospheric, space, and environmental communities.
Experimentally, we are also upgrading hardware and optics from the old lidar configuration to one that is much more sensitive. This involves changing from a 44-cm diameter telescope to one that is the equivalent of 2.5 meters. This upgrade also includes setting up the full detector chain—optical fibers, lenses, choppers, interference filters and photomultiplier tubes—and LabView software to control the whole system. The 30x increase in sensitivity will improve time resolution, reduce uncertainties, and increase the maximum altitude to 110 km. The greater altitude will also enable comparisons with the new Na lidar that Titus Yuan brought to USU from CSU and with the OH airglow observations that Mike Taylor makes at nearby Bear Lake Observatory.