HR: 0800h
AN: SA31A-0342    [Abstracts]
TI: Nonlinear 3D simulations of mesoscale structuring by multiple drives in high latitude plasma patches
AU: * Guzdar, P N
EM: guzdar@umd.edu
AF: IREAP, University of Maryland, College Park, MD 20742
AU: Gondarenko, N A
EM: ngondare@umd.edu
AF: IREAP, University of Maryland, College Park, MD 20742
AB: We will present the results for the nonlinear 3D simulations of the patch structuring with two primary sources of the instabilities, gradient drift instability (GDI) and velocity-shear driven instability, which are combined to account for the large variability of the statistical and spectral characteristics of the satellite data by Basu et al. [1988, 1990]. Due to the complexity of the different scale sizes involved in high latitudes, understanding the physics of the mesoscale structures is very important to determine the dominant mechanisms in the generation of the density and electric field fluctuations. We have convincingly demonstrated the nature of mesoscale structuring of high latitude patches by a combination of GDI and secondary Kelvin-Helmholtz (KH) instability followed by the tertiary generation of shear flow within the patches [Gondarenko and Guzdar, 2004a, 2004b]. However, the magnitude of the shear flow generated by these processes with the dominant GDI is weak and the magnitude of the electric field fluctuations is only a few millivolts per meter. The observations of plasma structures at high latitudes indicate that the electric field fluctuation magnitudes associated with velocity shear driven processes can be much larger (at least an order of magnitude) [Basu et al., 1988, 1990]. We investigate the interplay of the velocity-shear driven instability with the gradient drift instability and the effect of these two dominant instabilities on mesoscale structuring. We also present high-resolution simulation results obtained with a higher (sixth) order FD approximation scheme to validate the asymmetry in the density fluctuation spectra in the noon-midnight and dawn-dusk directions.
Basu et al. (1988) J. Geophys. Res., 93, 115 ; (1990) JGR, 95, 7799. Gondarenko N. A. and P. N. Guzdar (2004a) GRL, 31, L11802; (2004b) JGR, 109, A09301.
DE: 2439 Ionospheric irregularities
DE: 2475 Polar cap ionosphere
DE: 6929 Ionospheric physics (1240, 2400)
SC: SPA-Aeronomy [SA]
MN: Fall Meeting 2005