Statistics and Variability of Turbulence Dynamics in the Middle Atmosphere
Abstract
This project falls within the realm of the USAF mission of developing air defense systems, a component of which is the ongoing Airborne Laser (ABL) Program. The recent congressional mandate to develop an airborne missile defense system for the US will bolster the ABL program, since laser technology is a viable tool for such an effort. One of the major challenges of the ABL program is the development of laser-beam propagation codes. Such codes must account for the beam propagation through an extended turbulent medium, consisting of the bulk of the troposphere and stratosphere. From the operational perspective (Atmospheric Decision Aid, ADA), rigorous modeling of the refractive index structure function for long horizontal or nearly horizontal paths under high scintillation conditions characteristic of the atmosphere is imperative. In spite of demonstrated importance of stratification on atmospheric optical turbulence, currently available ABL phase screen theories hinge upon isotropic Kolmogorov spectrum (Rytov's theory), and hence cannot represent large amplitude fluctuations of atmospheric stratified turbulence. In the context of such turbulence the collusion between the stratification and shear leads to many intriguing phenomena such as the formation of thin, elongated turbulent layers (pancakes) and instabilities (such as Kelvin-Helmholtz (K-H) billowing, Figure 13) that ultimately break down into turbulence. The turbulence so generated is often patchy and temporally intermittent, characterized by strong anisotropy. It produces strong optical scintillation due to refractive index fluctuations, which needs to be quantified accurately in developing advanced beam control concepts for atmospheric laser-beam propagation.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 20, 2005
- Accession Number
- ADA435888
Entities
People
- Alex Mahalov
- Basil Nicolaenko
Organizations
- Arizona State University