March 18, 2010, 12:00 pm - 1:00 pm

March 18, 2010, 12:00 pm - 1:00 pm

Cluster and Double Star Observations of Magnetotail Transients

Andrew Walsh (Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Surrey, RH5 6NT, UK)

Multi-point observations made in space and on the ground are recognised as one of the best ways to advance our knowledge of the Earth's magnetosphere and the physical processes that operate within it. Most multi-spacecraft missions have either been of the formation-flying type (Cluster, ISEE 1 & 2) or the conjunction type (THEMIS). The Sino-European Double Star Project aimed to bridge the gap between the two by placing two spacecraft in orbits designed to maximse conjunctions with Cluster. Here I will discuss two examples of joint Cluster - Double Star measurements as applied to transient phenomena in the Earth's magnetotail - Magnetic Flux Ropes and Plasma Bubbles. In the magnetotail, magnetic flux ropes are a product of multiple X point reconnection and have been suggested as a cause of Travelling Compression Regions. In the presented interval, we observe two individual flux ropes with Cluster, one of which was observed concurrently with a TCR, and a third flux rope with Double Star TC-1, simultaneous with one of the Cluster flux ropes. The simultaneous existence of more than one flux rope provides strong evidence that multiple X point reconnection can occur in the magnetotail. Taking advantage of larger-separation Cluster data (10,000km from the 2005 tail season) and a favourable conjunction with Double Star TC-2 we make the first direct observations of the expected return flows around the flanks of a plasma bubble and track the bubble's evolution between Cluster (located 15RE downtail) and TC-2 (located just outside geosynchrnous orbit).