Empirical modeling of plasma sheet pressure and three‐dimensional force‐balanced magnetospheric magnetic field structure: 2. Modeling. Issue 10 (31st October 2013)

• Record Type: Journal Article
• Authors: Yue, Chao; Wang, Chih‐Ping; Zaharia, Sorin G.; Xing, Xiaoyan; Lyons, Larry
• Is Part Of: Journal of geophysical research. Volume 118:Issue 10(2013:Oct.)
• Page Start: 6166
• Page End: 6175
• Publication Date: 2013-10-31
• Subjects: Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1002/2013JA018943
• Languages: English
• ISSNs: 2169-9380

Abstract

<abstract abstract-type="main"> <title>Abstract</title> <p>[1] The magnetic field configuration is crucial to plasma sheet dynamics and magnetosphere‐ionosphere coupling. In this study we established 3‐D force‐balanced magnetic fields and investigated configuration changes with <italic>Kp</italic> and solar wind dynamic pressure (<italic>P</italic><sub>SW</sub>). Pressure distributions from the empirical model developed in Wang et al. (2013) were used for obtaining the force‐balanced field. Based on our model results, we found that (1) higher <italic>P</italic><sub>SW</sub> mainly enhances pressure in the tail plasma sheet, while larger convection during higher <italic>Kp</italic> drives plasma sheet further earthward, resulting in a pressure increase closer to the Earth; (2) comparing with the magnetic field changes due to increasing <italic>P</italic><sub>SW</sub>, the <italic>Kp</italic> associated pressure enhancement causes the azimuthal current density (<italic>J</italic><sub>ϕ</sub>) peak and field‐aligned currents (FACs) to move deeper earthward, the magnetic field to decrease further near Earth but increase more in the tail, and field lines to stretch more significantly; (3) as <italic>Kp</italic> and <italic>P</italic><sub>SW</sub> change, the whole plasma sheet remains stable to interchange instability but may be ballooning unstable in the midnight region at <italic>X</italic> between −15 and −10 <italic>R<sub>E</sub></italic>; (4) the force‐balanced configurations are characteristically different from the non‐force‐balanced Tsyganenko 89 (T89) magnetic field. A region of positive d<italic>Bz</italic>/d<italic>z</italic> in the near‐Earth region, which has been observed, is seen in our field but not in T89. On the other hand, a local equatorial <italic>Bz</italic> minimum is predicted by T89 but not by our model. <italic>J</italic><sub><italic>φ</italic></sub> bifurcation appears in the near‐Earth region as a result of our <italic>J</italic><sub><italic>φ</italic></sub> configuration being approximately aligned with field lines, while the T89 <italic>J</italic><sub><italic>φ</italic></sub> everywhere decreases monotonically with increasing Z by construction.</p> </abstract>