Dynamic fluid‐kinetic (DyFK) modeling of auroral plasma outflow driven by soft electron precipitation and transverse ion heating

Abstract

Abstract. We apply a recently developed dynamic fluid-kinetic (DyFK) model to simulate and investigate the effects of soft auroral electron precipitation and perpendicular ion heating by waves on the plasma outflow along auroral field lines. The DyFK model is constructed by coupling a fluid ionospheric model for the region from 120 to 800 km to a semikinetic treatment for topside through several RE altitude region. This approach, which is described in detail here, allows a partially self-consistent description of the plasma transport along highlatitude flux tubes where both low-altitude ionospheric heating and ionization production and loss as well as high-altitude energization and kinetic effects are incorporated and stressed. In the present work, we investigate the combined effects of the F region plasma production and electron heating by soft auroral electron precipitation and ion perpendicular wave heating at high altitudes, which produces ion conics. The auroral event simulated here involves 1.5 hours of moderate soft electron precipitation and relatively weak ion cyclotron waves along the magnetic field lines. The simulations reveal the F region electron heating and ionization

Simulating the cleft ion fountain at polar perigee altitudes

“…The dynamic fluid-kinetic (DyFK) model used in the present study is a modified version of that described in Estep et al (1999) and Wu et al (1999Wu et al ( , 2002). The DyFK model couples a truncated version of the field line interhemispheric plasma (FLIP) model (Richards and Torr, 1990) and generalized semi-kinetic (GSK) model (Wilson, 1992) across an overlapped boundary region.…”

“…In this study we present simulation results from a more complete high latitude ion transport model, our recently developed dynamic fluid-kinetic (DyFK) model Wu et al, 1999Wu et al, , 2002. The modeled O + field-aligned flow patterns within convecting flux tubes are qualitatively compared with O + flow patterns observed by the Polar spacecraft over the southern polar ionosphere.…”

“…This two-step energization of O + may be important in driving O + outflows as suggested by Moore et al (1996). Wu et al (1999Wu et al ( , 2002 examined the synergistic effects of soft electron precipitation at ionospheric altitudes and wave heating/parallel potential at higher altitudes using a dynamic fluid-kinetic (DyFK) model. Their calculations showed that the combined effects enhance O + outflow fluxes by an order of magnitude above the levels for one of the processes alone.…”

O<sup>+</sup> and H<sup>+</sup> ion heat fluxes at high altitudes and high latitudes

“…Two published models by Brown et al (1995) and Wu et al (1999) discussed ion outflow. These models are collisional at lower altitudes and collisionless at higher altitudes, which extend up to geocentric distances of 3 R E .…”

High-altitude and high-latitude O<sup>+</sup> and H<sup>+</sup> outflows: the effect of finite electromagnetic turbulence wavelength

“…Wu et al (2002) simulated ion outflow processes along auroral field lines with a dynamic fluid kinetic model which coupled a fluid ionospheric model to a semi-kinetic treatment for the topside through 3 R E region. Large-scale extended parallel electric fields were incorporated in addition to the soft auroral electron precipitation and wave-driven ion-heating processes simulated in Wu et al (1999). The ion velocity distribution evolves from bowl and suprathermal conic distributions at lower altitudes into mirrored conics and finally toroidal distributions at the top.…”