Preliminary empirical model of inner boundary of ion plasma sheet. Issue 6 (15th September 2015)

• Record Type: Journal Article
• Authors: Cao, J.B.; Zhang, D.; Reme, H.; Dandouras, I.; Sauvaud, J.A.; Fu, H.S.; Wei, X.H.
• Is Part Of: Advances in space research. Volume 56:Issue 6(2015)
• Page Start: 1194
• Page End: 1199
• Publication Date: 2015-09-15
• Subjects: Space sciences -- Periodicals; Astronautics -- Periodicals; Geophysics -- Periodicals; 500.505
• DOI: 10.1016/j.asr.2015.06.017
• Languages: English
• ISSNs: 0273-1177

Abstract

<abstract xml:lang="en" abstract-type="author" id="ab005"> <title id="st005">Abstract</title> <sec> <p id="sp0005">The penetration of the plasma sheet into the inner magnetosphere is important to both ring current formation and spacecraft charging at geosynchronous orbit. This paper, using hot ion data recorded by HIA of TC-1/DSP, establishes an empirical model of the inner boundary of ion plasma sheet (IBIPS) on the near equatorial plane. All IBIPS are located inside geocentric radial distance of 9 <italic>R<sub>E</sub></italic>. We divided local times (LT) into eight local time bins and found that during quiet times (<italic>Kp </italic>⩽ 2<sup>−</sup>), the IBIPS is closest to the Earth on the pre-midnight side (LT = 1930–2130) and farthest on the dawn side (LT = 0430–0730), which differs from previous spiral models. The geocentric radius of IBIPS in each local time bin can be described by a linear fitting function: <italic>R<sub>ps</sub> </italic>= <italic>A </italic>+ <italic>B<sub>kp</sub></italic> · <italic>Kp</italic>. The changing rate <italic>B<sub>kp</sub></italic> of the radius of IBIPS relative to <italic>Kp</italic> index on the midnight side (LT = 2230–0130) and post-night side (LT = 0130–0430) are the two largest (0.66 and 0.67), indicating that the IBIPS on the night side (LT = 2230–0430) moves fastest when <italic>Kp</italic> changes. Since the IBIPSs in different local times bins have different changing rates, both the size and shape of IBIPS change when <italic>Kp</italic> varies. The correlation coefficients between the radius of IBIPS and the instantaneous <italic>Kp</italic> increase with the increase of Δ<italic>T</italic> (the time difference between IBIPS crossing time and preceding <italic>Kp</italic> interval), which suggests that with the increase of Δ<italic>T</italic>, the radius of IBIPS is more and more controlled by instantaneous <italic>Kp</italic>, and the influence of preceding <italic>Kp</italic> becomes weaker. The response time of IBIPS to <italic>Kp</italic> is between 80 and 95 min. When Δ<italic>T</italic> > 95 min, the correlation coefficient basically keeps unchanged and only has a weak increase, suggesting that the IBIPS is mainly determined by the convection electric field represented by instantaneous <italic>Kp</italic>.</p> </sec> </abstract>