title: Temporal variability of the telluric sodium layer.
abstract: The temporal variability of the telluric sodium layer is investigated by analyzing 28 nights of data obtained with the Colorado State University LIDAR experiment. The mean height power spectrum of the sodium layer was found to be well fitted by a power law over the observed range of frequencies, 10 microHz to 4 mHz. The best-fitting power law was found be be 10(beta)nu(alpha), with alpha=-1.79+/-0.02 and beta=1.12+/-0.40. Applications to wavefront sensing require knowledge of the behavior of the sodium layer at kilohertz frequencies. Direct measurements at these frequencies do not exist. Extrapolation from low-frequency behavior to high frequencies suggests that this variability may be a significant source of error for laser guide star adaptive optics in large-aperture telescopes.
authors.affiliation: Department of Physics & Astronomy, University of British Columbia, Vancouver, Canada. sdavis@astro.ubc.ca
authors.forename: D Saul
authors.initials: DS
authors.lastname: Davis
authors.forename: Paul
authors.initials: P
authors.lastname: Hickson
authors.forename: Glen
authors.initials: G
authors.lastname: Herriot
authors.forename: Chiao-Yao
authors.initials: CY
authors.lastname: She