Short Term Minutes-timescale Temporal Variation Statistics of Sodium Layer Dynamics

Abstract

The brightness and height of the sodium laser guide star of adaptive optics could vary significantly due to the temporal dynamics of sodium column density and the mean height of the sodium layer. To measure these dynamics, an independent sodium Lidar is a necessity. Without such an instrument, it is almost impossible to discern the cause of the brightness variation of the laser guide star from the sodium layer's dynamics or other factors from the laser itself. For applications such as characterizing the performance of sodium laser for sodium laser guide star generation, minutes scale short term statistics of the sodium layers' abundance and height is extremely helpful for estimating the contribution of sodium layer's variation to the variation of laser guide star's brightness. In this paper, we analyzed our previous measurement of sodium layer dynamics that has been gathered in two winters, and presented the temporal variation statistics of sodium column density and mean height within a minute timescale based on our measurements.

First Sodium Laser Guide Star Asterism Launching Platform in China on the 1.8 m Telescope at Gaomeigu Observatory

“…Considering the instability of the laser output power and the change in sodium column density (Feng et al 2021), we have some uncertainties when we measure the brightness of different types of laser guide star asterisms.…”