Role of ion temperature anisotropy in multistage refilling of the outer plasmasphere

Journal Article · Wed May 01 04:00:00 EDT 1991 · Geophysical Research Letters (American Geophysical Union); (United States)

DOI:https://doi.org/10.1029/91GL00026· OSTI ID:5151913

Singh, N ^[1]

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1. Univ. of Alabama, Huntsville (United States)

Plasmaspheric refilling after geomagnetic storms is studied using a model in which the ion temperature anisotropy (TAN) is allowed to evolve self-consistently with the interhemispheric plasma flow. The refilling processes predicted from this TAN model and those from a model based on the assumption of temperature isotropy (TISO) are compared. TISO model predicts that a flux tube with L = 4 undergoes a substantial refilling in about 12 hours after a severe depletion and during this time the flows from the conjugate ionospheres remain supersonic with a flux {approximately}2 {times} 10{sup 8} cm{sup {minus}2}s{sup {minus}1}. The above refilling time is too short compared to observed refilling times. The tan model predicts much longer refilling time divided in two stages; during the early stage, the flows from the conjugate ionospheres are supersonic, and it is characterized by interhemispheric plasma exchange, shock formations and their propagations like in the TISO model. But in the TAN model, the supersonic flows last only over a few hours (< 5 hours) and the plasma in the flux tube develops a temperature anisotropy such that T{sub {vert bar}} > T{sub {perpendicular}}. This anisotropy causes a downward force, which balances the upward electric and pressure forces on ions keeping the flux tube depleted. The ensuing second stage starts when the temperature anisotropy begins to relax due to Coulomb collisions at high latitudes. In this stage the flow is generally subsonic and in the late stage of the refilling the equatorial density is seen to increase at a rate < 15 cm{sup {minus}3}/day.

• OSTI ID: 5151913
• Journal Information: Geophysical Research Letters (American Geophysical Union); (United States), Journal Name: Geophysical Research Letters (American Geophysical Union); (United States) Vol. 18:5; ISSN GPRLA; ISSN 0094-8276
• Country of Publication: United States
• Language: English

Related Subjects

640201* -- Atmospheric Physics-- Auroral
Ionospheric
&amp; Magetospheric Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ANISOTROPY
COMPARATIVE EVALUATIONS
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
EVALUATION
FLUID FLOW
ION TEMPERATURE
IONOSPHERE
MAGNETIC FLUX
MAGNETIC STORMS
MATHEMATICAL MODELS
PLANETARY IONOSPHERES
PLASMA DENSITY
PLASMA DRIFT
PLASMASPHERE
SUPERSONIC FLOW
WAVE PROPAGATION