The Effect of Finite 'Blob' Size on the Current Convective Instability in the Auroral Ionosphere.
Abstract
It has been suggested that the current convective instability may be responsible for the structuring, i.e., generation of density irregularities, of density enhancements (known as 'blobs') in the auroral ionosphere. However, previous theories have neglected the finite extent of the 'blob' along the geomagnetic field. In this paper we develop a non-local theory of the current convective instability which considers the finite extent of an ionospheric 'blob' parallel to the geomagnetic field. We find that the growth rate of the instability can be substantially reduced in the finite-sized 'blob' case from the value obtained in the local approximation for an infinitely long blob. For auroral ionosphere parameters, the reduction in the growth rate for medium scale irregularities (1-10 km) can be one to two orders of magnitude for the typical observed values of 'blob' sizes (approx. a few hundred km). Thus, it appears that the current convective instability is not a viable mechanism to generate scintillation causing irregularities, i.e., 1-10 km irregularities. Keywords: Auroral ionosphere; Auroral density irregularities; Current convective instability; and Nonlocal plasma theory.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 11, 1986
- Accession Number
- ADA166806
Entities
People
- Joseph D. Huba
- P. K. Chaturvedi
Organizations
- United States Naval Research Laboratory