A comparison of the relative effect of the Earth's quasi‐DC and AC electric field on gradient drift waves in large‐scale plasma structures in the polar regions. Issue 9 (17th September 2016)

• Record Type: Journal Article
• Authors: Burston, Robert; Mitchell, Cathryn; Astin, Ivan
• Is Part Of: Journal of geophysical research. Volume 121:Issue 9(2016:Sep.)
• Page Start: 9012
• Page End: 9019
• Publication Date: 2016-09-17
• Subjects: ionosphere -- electric field -- GDI; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1002/2016JA022676
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: Radio signals traversing polar cap plasma patches and other large‐scale plasma structures in polar regions are prone to scintillation. This implies that irregularities in electron concentration often form within such structures. The current standard theory of the formation of such irregularities is that the primary gradient drift instability drives a cascade from larger to smaller wavelengths that manifest as variations in electron concentration. The electric field can be described as the sum of a quasi‐DC and an AC component. While the effect of the quasi‐DC component has been extensively investigated in theory and by modeling, the contribution of the AC component has been largely neglected. This paper investigates the relative contributions of both components, using data from the Dynamics Explorer 2 satellite. It concludes that the contribution of the AC electric field to irregularity growth cannot be neglected. This has consequences for our understanding of large‐scale plasma structures in polar regions (and any associated radio scintillation) as the AC electric field component varies in all directions. Hence, its effect is not limited to the trailing edge of such structures, as it is for the quasi‐DC component. This raises the need for new experimental and modeling investigations of these phenomena. Key Points: Using DE2 data, the relative strengths of AC and DC electric field components in plasma structures in polar regions are compared In such data, the order of magnitude of AC component is found to be greater than the DC component in 60% of cases This implies that gradient drift waves are not confined to the trailing edge such structures