Development of High Altitude Clear Air Turbulence Models
Abstract
The high altitude clear air turbulence (HICAT) data were divided into subsets defined by season, altitude, topography, and flight heading. The shape of the power spectral density curves are shown to be a function of topography with the corresponding 'scale lengths' 500 feet for flights over water and flatland and increasing to 6000-8000 feet for flights over high mountains. Curves representing the percentage excess of the RMS of the area under the truncated PSD curves are logarithmic curves for the subsets defined by topography but are not simple logarithmic curves for the subsets defined by season or altitude. Ratios of the total RMS of the area under the PSD curves to the truncated area truncated at lambda = 2000 feet are given for the various scale lengths. Eight functions of atmospheric temperature and wind were shown to be significantly correlated with high altitude clear air turbulence. A significantly greater number of the observations of turbulence occurred with headwinds than with tailwinds. The percentage exceedance of the lengths of turbulent regions was shown to be a logarithmic function. The length of the turbulent regions and the intensity of the turbulence decreased with altitude above the turbulence cloud top.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1969
- Accession Number
- AD0866372
Entities
People
- David E. Waco
- Edward V. Ashburn
- Finis A. Mitchell
Organizations
- Lockheed Martin