Magnetopause response to variations in the solar wind: Conjunction observations between Cluster, TC-1, and SuperDARN

Abstract

[1] How the solar wind affects the location of the magnetopause has been widely studied and excellent models of the magnetopause based on in situ observations in the solar wind and at the magnetopause have been established, while the careful insight into the responses of the magnetopause to the variations in the solar wind can still provide us some new information about the processes in space plasmas. The short distance from Cluster to TC-1 on 9 March 2004, between 06:10 and 08:10 UT, gives us a good opportunity to precisely monitor the responses of the magnetopause to the variations in the solar wind. On the basis of the combined observations between Cluster, TC-1, and SuperDARN we analyze the magnetopause crossings associated with magnetopause motion or magnetic reconnection when the solar wind conditions have a series of variations. New results about the time delays for the propagation from the solar wind monitor to the magnetopause of the interplanetary magnetic fields (IMF) and of the solar wind dynamic pressure, respectively, and the intrinsic time for reconnection onset at the magnetopause are obtained. The most important feature of the event is that the dynamic pressure and the IMF in the solar wind do not arrive at the magnetopause at the same time, which will direct us to find out how the variation in the solar wind dynamic pressure is transported from the bow shock to the magnetopause. Another significant feature is that this event presents a shorter intrinsic time, ∼2 min, for reconnection onset at the dayside magnetopause than that given by the previous work of Le et al. (1993) and Russell et al. (1997).

Time delay of interplanetary magnetic field penetration into Earth's magnetotail

“…It is expected that there would be time difference between P dy and IMF for propagation inside the magnetosheath. However, the time difference is estimated to be only 5–7 min [ Zhang et al , ]. This lag time can be explained in terms of IMF being “frozen” in the shocked solar wind (magnetosheath) with reduced velocity, while disturbance of P dy is transported with a faster magnetosonic speed.…”

Storm time current distribution in the inner equatorial magnetosphere: THEMIS observations

“…C . Zhang et al ., 2011; Ganushkina et al , ; Shen et al , ], denoted as j φ . As pointed by Vogt et al [], with three point magnetic measurements, the current density can be obtained as if the direction of the current is known.…”

“…Different methods have been developed to derive the current density from Cluster four-point measurements based on a linear estimation from the Maxwell-Ampère's law [e.g., Chanteur, 1998;Dunlop et al, 2002;Shen et al, 2003]. Among them, Vallat et al [2005] and Q. H. Zhang et al [2011] provided current distribution around 4-5R E using the curlometer method [Dunlop et al, 1988[Dunlop et al, , 2002; Shen et al [2014] calculated the current density and studied local magnetic configuration variation during storm time using magnetic curvature analysis [Shen et al, 2003] and magnetic rotation analysis [Shen et al, 2007] methods. The four Cluster satellites are well suited for calculating the 3-D current density.…”

Distinct characteristics of asymmetric magnetic reconnections: Observational results from the exhaust region at the dayside magnetopause

“…In summary, the separation of the BRP and the PJP is a common feature of the exhaust region in asymmetric reconnections, regardless of the magnitude of the asymmetry. The exhaust region will generally move inward towards the magnetosphere as reconnection erodes the magnetopause24 because of the relative motion between the exhaust region and the TC-1; thus, the precise features of the separation distance as illustrated by δ xs in equation 4 cannot be achieved based on single-point observations. This type of investigation will be the topic of the analysis of the data resulting from the anticipated Magnetospheric Multiscale mission (MMS)25.…”