Abstract
Abstract. During steady magnetospheric convection (SMC) events the magnetosphere is active, yet there are no data signatures of a large scale reconfiguration, such as a substorm. While this definition has been used for years it fails to elucidate the true physics that is occurring within the magnetosphere, which is that the dayside merging rate and the nightside reconnection rate balance. Thus, it is suggested that these events be renamed Balanced Reconnection Intervals (BRIs). This paper investigates four diverse BRI events that support the idea that new name for these events is needed. The 3–4 February 1998 event falls well into the classic definition of an SMC set forth by Sergeev et al. (1996), while the other challenge some previous notions about SMCs. The 15 February 1998 event fails to end with a substorm expansion and concludes as the magnetospheric activity slowly quiets. The third event, 22–23 December 2000, begins with a slow build up of magnetospheric activity, thus there is no initiating substorm expansion. The last event, 17 February 1998, is more active (larger AE, AL and cross polar cap potential) than previously studied SMCs. It also has more small scale activity than the other events studied here.
Highlights
When the interplanetary magnetic field (IMF) is oriented opposite to that of Earth’s intrinsic magnetic field (Bz negative or southward), reconnection between the two field lines is favorable
Where Fpc is the amount of open flux in the polar cap, D and N are the dayside and nightside reconnection rates, respectively
Since there is no measurable loading of the tail, the Balanced Reconnection Intervals (BRIs) ends with the onset of the expansion phase of the substorm
Summary
Siscoe and Huang (1985) state the following formulation of Faraday’s Law:. Where Fpc is the amount of open flux in the polar cap, D and N are the dayside and nightside reconnection rates, respectively. This balance of reconnection rates occurs when large scale convection is steady in the magnetosphere It is a more physical based definition, as it is a measurement of the magnetospheric state rather than a lack of data signatures. If the reconnection rates are truly balanced, the openclosed boundary, and the amount of open magnetic flux in the polar cap (Fpc), should remain steady This new definition allows us to utilize the Fpc, which is derived using data from the Polar UVI and IMAGE FUV instruments, to identify BRI/SMC events. Their findings of “an intense current sheet in the inner magnetosphere and a thick midtail plasma sheet” supported the global convection pattern put forth by Sergeev et al (1996) When they increased the merging rate by 50% in magnitude by increasing the IMF Bz, they still had a case of quasi-steady reconnection in the tail.
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