Double Star TC-1 observations of component reconnection at the dayside magnetopause: a preliminary study
Zhang, T. L.; Dandouras, I.; Zhang, H.; Dunlop, M. W.; Liu, Z. X.; Carr, C. M.; Réme, H.; Fu, S. Y.; Pu, Z. Y.; Zong, Q. G.; Fazakerley, A.; Phan, T.; Xiao, C. J.; Wang, X. G.; Zhang, X. G.; Huang, Z. Y.
China, United Kingdom, United States, France, Austria
Abstract
In spring 2004 Double Star TC-1 measured a number of reconnection signatures at the dayside low-latitude magnetopause (MP) when there was a notable By component in the magnetosheath. In a number of events we can show that reconnection was operating nearby TC-1 in the subsolar MP region. In this paper we describe three representative events: (a) event on 21 March 2004 in which the reconnection site can be remotely monitored, the spacecraft was passing by the X-line; (b) event on 12 March 2004 in which TC-1 observed the magnetospheric part of the quadrupolar field, together with a consistent flow reversal; (c) event on 26 March 2004 which occurred for northward IMF, TC-1 observed a reversal of vy across the equatorial MP. In these events the shear angles across the MP were considerably smaller than 180°; a noticeable guide field was present. These observations are consistent with near equatorial component merging, suggesting that component reconnection preferably occurs at the dayside low-latitude MP. There is evidence that when a pronounced magnetic shear across the MP exists in the By component, reconnection may operate at the dayside low-latitude MP for northward IMF Bz.