Frozen flow or not? Investigating the predictability of the atmosphere

Adapting to the Atmosphere Conference 2014

物理学;地球科学

Bharmal, Nazim Ali^1

Department of Physics, Science Laboratories, South Road, Durham

DH1 3LE, United Kingdom^1

关键词: Analytic models;    Astronomical application;    Kolmogorov theory;    Potential benefits;    Spatial descriptions;    Taylor hypothesis;    Telescope aperture;    Temporal evolution;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/595/1/012003/pdf
DOI  :  10.1088/1742-6596/595/1/012003

来源: IOP

【 摘 要 】

The spatial description of aberrations produced by atmospheric turbulence for astronomical applications is agreed to be well modeled by the Kolmogorov theory of energy cascades. Instances of these aberrations can be easily generated using closed-form analytic models based on power-spectra following the von Karman model. However, in astronomical applications it is also the temporal evolution of these aberrations which is of interest. The description of this aspect is less well established, and is generally assumed to follow the Taylor Hypothesis over large time-scales as an approximation. This can be described as follows: if the aberrations are considered part of a flow that, for example, moves over a telescope aperture, then from the Lagrangian perspective the aberrations are static and as described by an instance of the spatial description described earlier. However, from the Euclidean perspective, the aberrations seem to just translate. Hence the alternative description of the Taylor Hypothesis as "frozen flow." This work summarizes the relevant findings of the applicability of frozen flow for the astronomical context, and demonstrates the potential benefits as well as shortcomings of using the frozen flow model for temporal evolution of these aberrations.