Simultaneous in-situ observations of
the feature of a typical FTE by
Cluster and TC1
Zhang Qinghe Liu Ruiyuan
Polar Research Institute of China
Email:qhzhang0405@sohu.com
Outline





Introduction
IMF and SW from ACE
The orbit of Cluster and TC1 in GSM
a) XZ-plane
b) XY-plane
Magnetic field feature of the FTE in LMN (MAV)
a) Cluster FGM data
b) TC1 FGM data
Particles feature of the FTE
Introduction



Magnetic reconnection is the predominant
mechanism by which solar wind energy and
momentum are transmitted into the earth
magnetospheric cavity.
The first in-situ observations of transient
reconnection in the vicinity of the high-latitude
dayside magnetopause were reported by
Haerendel et al.(1978) using HEOS-2 and Russell
and Elphic(1978,1979) using ISSE-1 and -2.
Termed “flux erosion events” by Haerendel et al. and
“flux transfer events” (FTEs) by Russell and Elphic.
Introduction
Cluster's multi-point measurement capability has revealed new
insights into the scale and location of the reconnection region, but
the following questions are still not clear.
--What is the evolution of a flux tube (FTE), from its generation at the
magnetopause to its disappearance in the global magnetospheric
convection?
--With the tetrahedron configuration of Cluster, is it possible to measure
the electrodynamics of an FTE, especially the distribution of the
field-aligned currents (with the Cluster curlometer) and the
ionospheric closure of the currents (with Ground-based
observations)?
....


Recently, many authors presented their researches about FTEs
coordinated satellites and ground-based observations, such as Wild
et al. (2001,2003,2005a,b), Lockwood et al. (2001a,b),and so on.
Introduction

Characters of FTEs:
a) bipolar signatures in the field component normal
to the magnetopause (Bn) positive-negative in the
northern hemisphere and negative-positive in the
southern hemisphere .
b) increases in total |B|

Location: vicinity of the magnetopause
Scale: ~Re
Lasted: few minutes


IFM and SW from ACE ---from CDAWEB
Have detracted the delay : ~64.5 mins
The orbit of Cluster and TC1 in GSM


Using
Tsyganenko-96
model
Input the real-time
parameters:
Pram: 1.61 Pa
Dst:
-6 nT
IMF By: -1.81nT
IMF Bz: -9.66nT
FGM feature of the FTE in LMN (MAV)

For Cluster:
a) In the exterior cusp
b) The outward magnetopause normal
determined by minimum variance analysis
(MVA) of Cluster 1 data during the interval of
11:10-11:20UT.
N= (0.59,0.25,0.77);
Typical bipolar structure in the Bn component positivenegative with |B| increased, the time at the core: 11:33:25
FGM feature of the FTE in LMN (MAV)
Using Cluster multi-point
measurements:



Assume the flux tube as an
interface and it almost does
not vary when Cluster pass.
The order :
Cl1 Cl2 Cl4 Cl3
We assume that the interface
is a planar with an average
normal velocity U (see right
side figure) .
(u x , u y , u z )
FGM feature of the FTE in LMN (MAV)

Using:
 R  nˆ  U n  t

Obtained the typical FTE:
speed:
Un =224.0km/s
direction: n=(-0.65,0.74,-0.19)
FGM feature of the FTE in ijk

For TC1:
a) In the magnetosheath
b) First use MVA determine the N, get L,M
Then rotates the LMN to local boundary
normal coordinate (ijk) make the magnetic
field bipolar structure only focus on the k
component (McWilliams, et al.,2004).
k=(-0.22,-0.56,-0.73)
Typical bipolar structure in the Bk component negativepositive with |B| increased, the time at the core: 11:32:29
Particles feature of the FTE
In the tube ,there are higher energy particles
than the background. Figure from CSDSWEB.
Particles feature of the FTE
In the tube ,there are higher energy particles
than the background. Figure from CSDSWEB
a) increases in
the tailward
speed of the
plasma;
b) little
decreases in
plasma number
density;
c) increases in
the plasma
temperature.
Figure from UK
Cluster data
centre.
Summary and following work





The typical FTE show the bipolar structure in the Bn component
positive-negative in the northern hemisphere and negativepositive in the southern hemisphere with |B| increased.
There also show the tailward moving characters of the flux tube.
In the tube, there are frozen higher speed and hotter protons,
electrons and ions than the background.
If the Cluster and TC1 observed the typical FTE was in the same
magnetic field line before reconnected, we can determine the
reconnection site.
We will find the evidence of the ionospheric signatures by
coordinating the ground-based observations.
Thank you for your attention