Walsh, A.P.; (2009) New perspectives on magnetotail dynamic processes from combined cluster and double star observations. Doctoral thesis , UCL (University College London).

Preview

PDF 18606.pdf Download (17MB)

Abstract

In this thesis, observations of the Earth's magnetotail from ESA's four Cluster and the two Sino-European Double Star spacecraft are presented. The observations are of intervals where data from the combination of Cluster and Double Star provide insights into the dynamics of the magnetotail that are not possible using data from one mission alone. In the �first study, observations of three magnetic flux ropes are presented, two of which were detected near-simultaneously at Cluster and Double Star TC-1, while the third was detected by Cluster, along with a TCR a few minutes later. The observations represent the �first observations of multiple flux ropes existing in the magnetotail simultaneously, providing evidence that flux rope orientation is influenced by neutral sheet tilt and provide further evidence that TCRs in the lobes are caused by the passage of flux ropes in the plasma sheet. In the second study, a detailed analysis of a plasma bubble is presented, including the �first direct observations of the return flows around the flanks of the plasma bubble that are expected from theory and simulation. Furthermore a partially stagnant depleted wake behind the plasma bubble, not predicted by theory or simulation was discovered and the cross-tail extent of the bubble was measured to be 3RE. The fi�rst observations of near-Earth bubble features are also reported. Finally, in the third study, the substorm onset process itself is investigated using a wide array of space- and ground-based instrumentation. A pseudobreakup and later substorm onset are distinguished using both geomagnetic and auroral data and the establishment of the substorm current wedge is observed in-situ using the TC-2 and GOES12 spacecraft. A link between higher latitude geomagnetic activity and the fast flows and plasma sheet expansion related to the reconnection of lobe fi�eld lines is also posited.

Download activity - last month

Export as CSVJSONXML

Download activity - last 12 months

Export as XMLJSONCSV

Downloads by country - last 12 months

Export as JSONCSVXML

Archive Staff Only

View Item