Investigation of turbulent processes in magnetospheric boundary layers

A self-consistent non-evolving two dimensional slab model of a viscous low-latitude boundary layer (LLBL) coupled to the ionosphere was developed by Phan, et al., (1989). Numerical results from the model and possible use of observations to determine the model parameters are discussed. The dynamical model developed by Lotko, et al., (1987) was used by Lotko and Shen (1991) to examine dynamical processes relevant to the LLBL with particular application to post-noon auroral shear layers. Initial results from a magnetohydrodynamic study of flank-side mangetopause boundary configuration are described. Effects of compressibility, scalar viscosity, and electrical resistivity are included in the MHD equations

YACIMIENTO DE BALOS [Material gráfico]

Copia digital. Madrid : Ministerio de Educación, Cultura y Deporte, 201

How Jupiter's Unusual Magnetospheric Topology Structures Its Aurora

Jupiter's bright persistent polar aurora and Earth's dark polar region indicate that the planets' magnetospheric topologies are very different. High-resolution global simulations show that the reconnection rate at the interface between the interplanetary and jovian magnetic fields is too slow to generate a magnetically open, Earth-like polar cap on the timescale of planetary rotation, resulting in only a small crescent-shaped region of magnetic flux interconnected with the interplanetary magnetic field. Most of the jovian polar cap is threaded by helical magnetic flux that closes within the planetary interior, extends into the outer magnetosphere and piles-up near its dawnside flank where fast differential plasma rotation pulls the field lines sunward. This unusual magnetic topology provides new insights into Jupiter's distinctive auroral morphology

Ionospheric Control of Magnetic Reconnection

The ionosphere influences dayside and nightside magnetic reconnection through its electrodynamic and inertial couplings to the magnetosphere. The distribution of high-speed plasma flows observed at distances of 10-30 earth radii in the magnetotail neutral sheet is highly skewed toward the premidnight sector due to electrodynamic coupling. These flows are a product of nightside reconnection, and numerical simulations indicate that the primary causal agent for their observed asymmetry is the meridional gradient in the ionospheric Hall conductance. Ionospheric outflows also have the capacity to change the dynamics and rate of nightside reconnection. Periodic substorms are observed for strong and steady solar wind driving in many data sets, but they occur in geospace simulations only when ionospheric outflows are included. When circulated through the plasmasheet and energized to populate the ring current, ions of ionospheric origin can also inflate the dayside magnetosphere, particularly during storm conditions. The result is a change in the shape of the magnetopause boundary, in the balance between convective and reconnective transport of magnetic flux through the magnetosheath and in the cross polar cap potential. These effects and their physical origins are demonstrated using results from global simulations

Effects of auroral potential drops on plasma sheet dynamics

©2016. American Geophysical Union. All Rights Reserved. The reaction of the magnetosphere-ionosphere system to dynamic auroral potential drops is investigated using the Lyon-Fedder-Mobarry global model including, for the first time in a global simulation, the dissipative load of field-aligned potential drops in the low-altitude boundary condition. This extra load reduces the field-aligned current (j || ) supplied by nightside reconnection dynamos. The system adapts by forcing the nightside X line closer to Earth, with a corresponding reduction in current lensing (j || /B = constant) at the ionosphere and additional contraction of the plasma sheet during substorm recovery and steady magnetospheric convection. For steady and moderate solar wind driving and with constant ionospheric conductance, the cross polar cap potential and hemispheric field-aligned current are lower by approximately the ratio of the peak field-aligned potential drop to the cross polar cap potential (10â15%) when potential drops are included. Hemispheric ionospheric Joule dissipation is less by 8%, while the area-integrated, average work done on the fluid by the reconnecting magnetotail field increases by 50% within |y| < 8 R E . Effects on the nightside plasma sheet include (1) an average X line 4 R E closer to Earth; (2) a 12% higher mean reconnection rate; and (3) dawn-dusk asymmetry in reconnection with a 17% higher rate in the premidnight sector.Link_to_subscribed_fulltex

Medium Range Thermosphere Ionosphere Storm Forecasts

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