Radar Turbulence Estimates. Effects of Wind Shear and Reflectivity Factor Gradients.
Abstract
Analysis of Doppler radar spectral width provides an estimate of the turbulence eddy dissipation rate (epsilon), which in turn can be correlated to atmospheric turbulence. The width of the Doppler spectrum provides an overestimate of the turbulence eddy dissipation rate. This overestimate may be corrected to some extent by the removal of wind shear and reflectivity factor gradients from the Doppler spectrum variance. Reflectivity factor gradients and radial velocity shears in three directions (azimuthal, vertical, and radial) are computed for points along an aircraft track. The gradient and shear effects are removed from the Doppler variance and the turbulence eddy dissipation rate is estimated using both the total and the corrected variances. Both radar estimates of the turbulence dissipation rates are then correlated with estimates of eddy dissipation rates derived from in-situ aircraft measurements. Results indicate that the only gradients significantly affecting the radar estimates are those of radial velocity shear components along the vertical or azimuthal directions. Corrections for these effects result in some improvements in the radar turbulence estimate, but the improvements are very small at the short ranges observed here. Results suggest that the gradient effects may be minor when compared to the other sources of error in the estimate of turbulence dissipation rates.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1985
- Accession Number
- ADA151876
Entities
People
- S. J. Sycuro
Organizations
- Air Force Institute of Technology