Comparison of the open‐closed separatrix in a global magnetospheric simulation with observations: The role of the ring current

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95344/1/jgra20421.pd

Observations of Mercury's northern cusp region with MESSENGER's Magnetometer

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95510/1/grl29143.pd

First results from the Cassini radio occultations of the Titan ionosphere

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95691/1/jgra19260.pd

MESSENGER observations of Mercury's magnetic field structure

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/96229/1/jgre3136.pd

MESSENGER and Mariner 10 flyby observations of magnetotail structure and dynamics at Mercury

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94896/1/jgra21525.pd

Ion temperature anisotropy effects on threshold conditions of a shear-modified current driven electrostatic ion-acoustic instability in the topside auroral ionosphere

Temperature anisotropies may be encountered in space plasmas when there is a preferred direction, for instance, a strong magnetic or electric field. In this paper, we study how ion temperature anisotropy can affect the threshold conditions of a shear-modified current driven electrostatic ion-acoustic (CDEIA) instability. In particular, this communication focuses on instabilities in the context of topside auroral F-region situations and in the limit where finite Larmor radius corrections are small. We derived a new fluid-like expression for the critical drift which depends explicitly on ion anisotropy. More importantly, for ion to electron temperature ratios typical of F-region, solutions of the kinetic dispersion relation show that ion temperature anisotropy may significantly lower the drift threshold required for instability. In some cases, a perpendicular to parallel ion temperature ratio of 2 and may reduce the relative drift required for the onset of instability by a factor of approximately 30, assuming the ion-acoustic speed of the medium remains constant. Therefore, the ion temperature anisotropy should be considered in future studies of ion-acoustic waves and instabilities in the high-latitude ionospheric F-region