Modeling of Sporadic-E Structures from Wind-Driven Kelvin-Helmholtz Turbulence
Abstract
Atmospheric wind shears control the irregularity structure in the E-region. Near 100 km altitude, where the ion collision frequency is much larger than the ion cyclotron frequency, the degree of shear turning and the direction of maximum shear gradient determine the location of the E-layer peak. The effects of speed shears on the three-dimensional structure of the E-layer are modeled using a system of coupled equations for continuity and momentum that describes both the neutrals and plasma. In the coupled model, the large amplitude components of the neutral wind shear drive the neutral atmosphere unstable and produce Kelvin- Helmholtz (K-H) billows. At the same time, the three-dimensional structure of the same wind shear compresses the ions vertical profile that is not necessarily centered on the node of the wind shear. The shear component is the source of Kelvin-Helmholtz turbulence and it produces quasi-periodic (Q-P) irregularities in the layer along the horizontal direction of the shear. The location of the turbulence in the ions is dependent on the offset lifting or lowering by the turning component of the neutral wind shear. The numerical results of the model study are consistent with the radar and optical observations.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 2006
- Accession Number
- ADA477029
Entities
People
- Joseph Werne
- Miguel F. Larsen
- P. A. Bernhardt
Organizations
- United States Naval Research Laboratory