A theoretical study of thermospheric composition perturbations during an impulsive geomagnetic storm

Journal Article · Thu Aug 01 04:00:00 EDT 1991 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/91JA00678· OSTI ID:5181285

Burns, A G; Killeen, T L ^[1]; Roble, R G ^[2]

---

1. Univ. of Michigan, Ann Arbor (United States)
2. National Center for Atmospheric Research, Boulder, CO (United States)

The compositional response of the neutral thermosphere to an impulsive geomagnetic storm has been investigated using a numerical simulation made with the National Center for Atmospheric Research thermospheric general circulation model (NCAR-TGCM). Calculated time-dependent changes in neutral thermospheric composition have been studied, together with detailed neutral parcel trajectories and other diagnostic information from the model, to gain a greater understanding of the physical mechanisms responsible for composition variability during geomagnetic storms and, in particular, to investigate the causes of the positive and negative ionospheric storm effects. The following principal results were obtained from this study. (1) Calculated perturbations in thermospheric composition following the onset of an impulsive geomagnetic storm were found to be in good qualitative agreement with the previous experimental statistical study of storm time thermospheric morphology by Proelss. (2) During the initial (onset) phase of the simulated storm, upward vertical winds occurred in the auroral zone and downward winds occurred in the central magnetic polar cap. (3) The largest perturbations in mass mixing ratio of nitrogen at F region altitudes were found to be associated with parcels of neutral gas that travelled through the cusp region and with parcels that were trapped within the auroral zone for a long time. (4) Storm time enhancements in {Psi}{sub N{sub 2}} were found to occur in the midnight and early morning sectors both within and equatorward of the auroral zone, and these were determined to be associated with the advective effects of the large antisunward polar cap neutral winds.

• OSTI ID: 5181285
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 96:A8; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640201* -- Atmospheric Physics-- Auroral
Ionospheric
& Magetospheric Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CHEMICAL COMPOSITION
COMPUTERIZED SIMULATION
EARTH ATMOSPHERE
F REGION
FLUCTUATIONS
GENERAL CIRCULATION MODELS
IONOSPHERE
IONOSPHERIC STORMS
MAGNETIC STORMS
MATHEMATICAL MODELS
PLANETARY IONOSPHERES
POLAR CUSP
SIMULATION
THERMOSPHERE
TIME DEPENDENCE
VARIATIONS
WIND