Remote Investigation of Tropospheric Turbulence by Two-Dimensional Analysis of Stellar Scintillation

Abstract

Several geophysical parameters can be deduced from multidimensional statistical analysis of stellar scintillation. In particular, the motion of the various atmospheric turbulent layers can be determined both in magnitude and direction, in addition to their turbulence strength (as measured by CN2 or Cr2) as a function of attitude. Until now, sequential analysis methods took ?20 min, during which time stationary could not be guaranteed due to intermittency. Here we present a system which is faster due to better use of available information. It consists of a very light-sensitive image receiver (television camera), followed by a specialized numerical computer (two-dimensional correlator) which utilizes in real time the spatial distribution of the irradiance of a large telescope entrance pupil. This apparatus allows us to identify fast temporal variations of the vertical profiles of turbulence strength, using soundings only 10 s apart. By tracking the double-star ? Andromedae, which has a wider angle between its two components, the present poor resolution may be doubled.