Space Plasma Space Plasma Research at UTAResearch at UTA

J. L. HorwitzJ. L. HorwitzDepartment of PhysicsDepartment of Physics

The University of Texas at The University of Texas at ArlingtonArlington

UTA Space Plasma GroupUTA Space Plasma Group

Dr. J. L. Horwitz, Professor and Dr. J. L. Horwitz, Professor and Department ChairDepartment Chair

Dr. Wen Zeng, Post-Doctoral Dr. Wen Zeng, Post-Doctoral ResearcherResearcher

Ms. Fajer Jaafari, Doctoral Ms. Fajer Jaafari, Doctoral Graduate StudentGraduate Student

Cf. also Dr. Yi-Jiun Su, Assistant Cf. also Dr. Yi-Jiun Su, Assistant Professor of Physics Professor of Physics

Funded by National Science Funded by National Science Foundation and NASAFoundation and NASA

MagnetosphereMagnetosphere

MagnetosphereMagnetosphere

High-latitude IonosphereHigh-latitude Ionosphere

AurorasAuroras

POLAR/TIDE/UVI observations of POLAR/TIDE/UVI observations of ionospheric field-aligned flows and ionospheric field-aligned flows and

auroral forms at 5000 kmauroral forms at 5000 km Stevenson et al.[2001] Stevenson et al.[2001]

employed POLAR employed POLAR Southern perigee Southern perigee observations to elicit observations to elicit relationships of high-relationships of high-latitude Olatitude O+ + field-aligned field-aligned flows observed by TIDE flows observed by TIDE to auroral forms by UVI. to auroral forms by UVI.

Typically, auroral Typically, auroral emissions associated with emissions associated with upflows, dark regions upflows, dark regions with down-flows.with down-flows.

POLAR/TIDE Parallel Flows with POLAR/TIDE Parallel Flows with Auroral Forms for May 4,1996Auroral Forms for May 4,1996

It is useful to divide the It is useful to divide the field-aligned ionospheric field-aligned ionospheric flows according to altitude flows according to altitude region:region:

F-region/topside up/down F-region/topside up/down flowsflows-->-->300--1000 km 300--1000 km altitude, <1-2 eV, gravitation-altitude, <1-2 eV, gravitation-ally-bound, influenced by ally-bound, influenced by frictional ion heating, ambi-frictional ion heating, ambi-polar electric fields, soft polar electric fields, soft electron precipitation-Te, electron precipitation-Te, ionization. ionization.

Energized ion outflows--Energized ion outflows-->>1200-3 R1200-3 REE, 10-10, 10-1044 eV, conics, eV, conics, beams, perp. wave heating, beams, perp. wave heating, parallel E-fields, etc. parallel E-fields, etc.

Dynamic Fluid-Kinetic(DyFK) treatment Dynamic Fluid-Kinetic(DyFK) treatment for ionospheric field-aligned flowsfor ionospheric field-aligned flows

Estep et al.[1999] and Wu et al.Estep et al.[1999] and Wu et al.[1999, 2002] developed a time-[1999, 2002] developed a time-dependent treatment for treating dependent treatment for treating field-aligned plasma flow, joining field-aligned plasma flow, joining a fluid treatment for the a fluid treatment for the ionosphere (120-1100 km) to a ionosphere (120-1100 km) to a GSK treatment for the upper GSK treatment for the upper altitude regions(800 km up)altitude regions(800 km up)

Treating effects of soft electron Treating effects of soft electron precipitation, transverse ion precipitation, transverse ion heating and hot plasma-driven heating and hot plasma-driven driven potentials, including a driven potentials, including a “pressure cooker” situation.“pressure cooker” situation.

Wu et alWu et al.[1999].[1999]

POLAR/TIDE-DyFK Comparisons in Cleft POLAR/TIDE-DyFK Comparisons in Cleft Ion Fountain Paradigm[Tu et al., 2005]Ion Fountain Paradigm[Tu et al., 2005]

O+ Field-aligned Velocities

• DyFK simulated • Polar/TIDEmeasured

DyFK/TIDE

IMAGE/RPI Electron DensitiesIMAGE/RPI Electron Densities

DyFK-IMAGE/RPI Comparisons: Simulation DyFK-IMAGE/RPI Comparisons: Simulation Convection Trajectories[Tu et al., 2004b]Convection Trajectories[Tu et al., 2004b]

DyFK-IMAGE/RPI-DMSP Profile DyFK-IMAGE/RPI-DMSP Profile 3 Comparison [Tu et al., 2004b]3 Comparison [Tu et al., 2004b]

DyFK-IMAGE/RPI-DMSP Profile 2 DyFK-IMAGE/RPI-DMSP Profile 2 comparison with and without auroral comparison with and without auroral processes [Tu et al., 2004b]processes [Tu et al., 2004b]

Characteristic Ion Distributions in the Characteristic Ion Distributions in the Dynamic Auroral Transition RegionDynamic Auroral Transition Region

Zeng et al.[2005]Zeng et al.[2005]