Abstract
Abstract. A number of flux transfer events (FTEs) were observed between 09:00 and 12:00 UT on 11 February 2004, during southward and dawnward IMF, while the Cluster spacecraft array moved outbound through the northern, high-altitude cusp and dayside high-latitude boundary layer, and the Double Star TC-1 spacecraft was crossing the dayside low-latitude magnetopause into the magnetosheath south of the ecliptic plane. The Cluster array grazed the equatorial cusp boundary, observing reconnection-like mixing of magnetosheath and magnetospheric plasma populations. In an adjacent interval, TC-1 sampled a series of sometimes none standard FTEs, but also with mixed magnetosheath and magnetospheric plasma populations, near the magnetopause crossing and later showed additional (possibly turbulent) activity not characteristic of FTEs when it was situated deeper in the magnetosheath. The motion of these FTEs are analyzed in some detail to compare to simultaneous, poleward-moving plasma concentration enhancements recorded by EISCAT Svalbard Radar (ESR) and "poleward-moving radar auroral forms" (PMRAFs) on the CUTLASS Finland and Kerguelen Super Dual Auroral Radar Network (SuperDARN) radar measurements. Conjugate SuperDARN observations show a predominantly two-cell convection pattern in the Northern and Southern Hemispheres. The results are consistent with the expected motion of reconnected magnetic flux tubes, arising from a predominantly sub-solar reconnection site. Here, we are able to track north and south in closely adjacent intervals as well as to map to the corresponding ionospheric footprints of the implied flux tubes and demonstrate these are temporally correlated with clear ionospheric velocity enhancements, having northward (southward) and eastward (westward) convected flow components in the Northern (Southern) Hemisphere. The durations of these enhancements might imply that the evolution time of the FTEs is about 18–22 min from their origin on magnetopause (at reconnection site) to their addition to the magnetotail lobe. However, the ionospheric response time in the Northern Hemisphere is about 2–4 min longer than the response time in the Southern Hemisphere.
Highlights
Magnetic reconnection is a fundamental plasma process, resulting in energy and momentum transfer from the solar wind to the magnetosphere
The velocity enhancements lasted about 18–22 min for both the flux tubes (FTEs) i observed by TC-1 and the FTE 2 measured by Cluster, which might suggest that the evolution time of FTEs is about 18–22 min from their origin on magnetopause to their addition to the magnetotail lobe
Comparing the ionospheric convections in both hemispheres, we find the velocity enhancements starting from 09:25 and 11:23 UT in the Northern Hemisphere and from 09:23 and 11:19 UT in the Southern Hemisphere for the FTE i observed by TC-1 and the FTE 2 measured by Cluster, respectively, which suggests the ionospheric response time in the Northern Hemisphere is 2 min later for the FTE i observed by TC-1 and 4 min later for the FTE 2 measured by Cluster than in the Southern Hemisphere
Summary
Magnetic reconnection is a fundamental plasma process, resulting in energy and momentum transfer from the solar wind to the magnetosphere. We analyze several medium to large scale FTEs which were observed by the Cluster array, at the highlatitude magnetopause, or by the TC-1 spacecraft, south of the subsolar magnetopause, simultaneously measured by the ESR and conjugately observed by the CUTLASS Finland and Kerguelen SuperDARN radars ( observing the ionospheric plasma flow, Greenwald et al, 1995; Chisham et al, 2007) measuring the global ionospheric convection. These FTEs are interpreted as reconnection generated signatures. We comment on other features of the data, focusing on additional magnetic activity at TC-1
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