Turbulence in the atmosphere drives the formation of temperature inhomogeneities that scatter and diffract propagating electromagnetic waves, adversely affecting laser weapons and high-resolution optical systems. Military operations require reliable turbulence profiles for the development and validation of turbulence prediction models. This research investigated the false turbulence contribution caused by well-known temperature steps in the vertical profile of the atmosphere, especially in the stratosphere. The homogeneity and isotropy requirements of structure functions were used to develop a technique to remove the false contribution to the temperature structure constant, Cr(2). Both 1.54 cm and 5.82 m vertical resolution profiles with 0.001 to 0.01 K temperature resolution were collected from a balloon flight. Steps of 0.1 to 1 K in the vertical temperature profile produce abrupt changes in the mean temperature that obscure the measurement of the actual turbulent fluctuations. Removing these anomalies exposed the underlying Cr(2) distribution. Application of the new technique for several sampling intervals revealed a Kolmogorov inertial subrange extending from approx. 25 cm to approx. 10 m. The potential of this technique to compute the isoplanatic angle, theta0, coherence length, r0, and Greenwood frequency, f(g), reliably by using inexpensive balloons should benefit airborne and space-based laser programs.
展开▼
