Initial ISEE magnetometer results - Magnetopause observations
Initial ISEE magnetometer results - Magnetopause observations
复制标题
DOI：
10.1007/978-94-009-9527-7_26
复制
发表时间：
1978-12
影响因子：
10.3
通讯作者：
C. Russell;R. Elphic
中科院分区：
文献类型：
--
作者：
C. Russell;R. Elphic
本文对距离仅几百公里的ISEE-1和ISEE-2航天器所获得的磁层顶磁场剖面进行了四次观测。在这些通行证之一的磁鞘场是北，在一个是稍微南，并在两个强烈南。磁层顶的速度被发现是非常不规则的，范围从4到超过40 km s-1，变化的时间比航天器穿越边界所需的时间短。厚度范围从500到超过1000公里。明确的证据，重新连接时，磁鞘场是向南的数据。然而，这一证据并不是经典的旋转不连续特征的形式。相反，它是以通量转移事件的形式出现的，在这种情况下，重连在几分钟或更短的时间内开始和停止，导致通量管从磁层脱落。由于边界法线的改变，在磁鞘和外磁层中都可以找到通量传输事件的证据。特别是，他们的存在时，磁层顶交叉失效的磁层顶结构通常的二维分析。这些通量转移事件不仅可能是磁层顶重联的主要方式，而且也可能是磁层顶振荡的重要来源，因此也是外磁层脉动的重要来源。根据ISEE观测到的通量转移事件，两天的通量转移速率估计为2 × 1012 Maxwells/s。在ISEE时未检测到的事件以及FTE通过ISEE后继续重新连接可能导致这些时间的重新连接率更高。
The magnetic field profiles across the magnetopause obtained by the ISEE-1 and -2 spacecraft separated by only a few hundred kilometers are examined for four passes. During one of these passes the magnetosheath field was northward, during one it was slightly southward, and in two it was strongly southward. The velocity of the magnetopause is found to be highly irregular ranging from 4 to over 40 km s-1and varying in less time than it takes for a spacecraft to cross the boundary. Thicknesses ranged from 500 to over 1000 km.Clear evidence for reconnection is found in the data when the magnetosheath field is southward. However, this evidence is not in the form of classic rotational discontinuity signatures. Rather, it is in the form of flux transfer events, in which reconnection starts and stops in a matter of minutes or less, resulting in the ripping off of flux tubes from the magnetosphere. Evidence for flux transfer events can be found both in the magnetosheath and the outer magnetosphere due to their alteration of the boundary normal. In particular, their presence at the time of magnetopause crossings invalidates the usual 2-dimensional analysis of magnetopause structure. Not only are these flux transfer events probably the dominant means of reconnection on the magnetopause, but they may also serve as an important source of magnetopause oscillations, and hence of pulsations in the outer magnetosphere. On two days the flux transfer rate was estimated to be of the order of 2 × 1012Maxwells per second by the flux transfer events detected at ISEE. Events not detectable at ISEE and continued reconnection after passage of an FTE past ISEE could have resulted in an even greater reconnection rate at these times.