Atmospheric turbulence analysis with the Keck adaptive optics systems

The wavefront sensors of adaptive optics systems of astronomical telescopes collect an abundance of high temporal resolution information about the distortions that are introduced to the incoming wavefront by atmospheric turbulence. Although this information can theoretically be used to analyze the turbulence conditions above the telescope at the given time, it is often discarded. The reason for this dismissal of seemingly useful information is usually the difficulty of separating atmospheric and instrumental contributions to the wavefront sensor measurements and thus of obtaining reliable estimates of the atmospheric turbulence conditions. In this paper we describe an effort to overcome these problems for wavefront sensor measurements taken by the Keck telescopes on Mauna Kea. We discuss different methods of deriving turbulence parameters, such as coherence length and time and the outer scale of turbulence, and present first results.