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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 109, A09301, doi:10.1029/2004JA010504, 2004

Plasma patch structuring by the nonlinear evolution of the gradient drift instability in the high-latitude ionosphere

N. A. Gondarenko

Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland, USA


P. N. Guzdar

Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland, USA


Abstract

Results from the three-dimensional nonlinear simulations of the gradient drift instability to study structuring in high-latitude plasma patches are presented. Simulations demonstrate that the existence of the mesoscale structures (10 km to 100 m) on both leading and trailing edges and inside a patch is due to (1) the nonlinear development of the gradient drift instability (GDI) or due to (2) occasional reversal of the direction of convection. The high-resolution simulation data have a dynamic range that allows us to make detailed comparisons with the observed density and velocity fluctuation spectra. We use the measured ion density and horizontal velocity data from the Dynamic Explorer 2 (DE 2) spacecraft examined by Kivanç and Heelis [1997] to compare them with our simulations. Density structures in the leading and trailing edges of patches have been examined, and comparison of statistical characteristics of the average density gradient on these edges with those in the work by Coley and Heelis [1998] has been performed. The dynamics and evolution of the density fluctuations over the realistic time scale are shown, thereby providing a significant evidence of the existence of the GDI at high latitudes as a structure-generating mechanism and a first principle understanding of the hierarchy of the instabilities involved in the observed structuring in high-latitude plasma patches.

Received 26 March 2004; accepted 23 June 2004; published 4 September 2004.

Keywords: plasma patch structuring; 3-D nonlinear simulations; gradient-drift instability; irregularities in high-latitude plasma patches.

Index Terms: 2439 Ionosphere: Ionospheric irregularities; 2475 Ionosphere: Polar cap ionosphere; 7843 Space Plasma Physics: Numerical simulation studies; 7863 Space Plasma Physics: Turbulence.

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Citation: Gondarenko, N. A., and P. N. Guzdar (2004), Plasma patch structuring by the nonlinear evolution of the gradient drift instability in the high-latitude ionosphere, J. Geophys. Res., 109, A09301, doi:10.1029/2004JA010504.