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Temporal variability of the telluric sodium layer
D Saul Davis1, Paul Hickson, Glen Herriot
1Department of Physics & Astronomy, University of British Columbia, Vancouver, Canada. sdavis@astro.ubc.ca
Temporal variability in the Earth's sodium layer was studied using LIDAR. Extrapolation suggests this variability may significantly impact laser guide star adaptive optics for large telescopes.
Area of Science:
- Atmospheric physics
- Optical astronomy
Background:
- The Earth's sodium layer is crucial for laser guide star adaptive optics.
- Understanding its temporal variability is essential for astronomical observations.
Purpose of the Study:
- To investigate the temporal variability of the telluric sodium layer.
- To assess the potential impact of this variability on astronomical instrumentation.
Main Methods:
- Analysis of 28 nights of data from the Colorado State University LIDAR experiment.
- Characterization of the sodium layer's mean height power spectrum.
- Power law fitting to observed frequency ranges (10 microHz to 4 mHz).
Main Results:
- The sodium layer's power spectrum follows a power law: 10(beta)nu(alpha).
- Best-fit parameters: alpha=-1.79+/-0.02 and beta=1.12+/-0.40.
- Extrapolation to kilohertz frequencies indicates potential wavefront sensing errors.
Conclusions:
- The temporal variability of the sodium layer exhibits power-law behavior.
- High-frequency extrapolation suggests significant error sources for laser guide star adaptive optics.
- Further research is needed to validate high-frequency behavior and mitigate potential errors.
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