Nonlinear Electrostatic Solitary Waves Observed in Connection with the 24 August 2005 Super-Substorm

Nonlinear electrostatic solitary waves (ESWs) are often observed in the magnetotail and sometimes are clearly seen to be associated with substorm processes. We present Cluster Wideband Data (WBD) from three of the four Cluster satellites showing the presence of ESWs at the onset in the main phase of the so-called super- substorm on 24 August 2005. Although ESWs are present in the observations for the two hours on either side of this onset, the ones that are observed at main phase onset are generally 1) more numerous, 2) of larger electric field amplitude, and 3) trending toward shorter time scales. In addition, there are significant differences in the detection of ESWs across the three Cluster satellites, which we discuss. For example, Cluster 1 detects enhanced ESWs for a much longer period of time after onset than Cluster 4. The Cluster satellites are approximately 6,000 km apart at this time. We compare and contrast the ESW observations from 24 August 2005 with those from another substorm during which Cluster was in the magnetotail and magnetic reconnection was observed. We briefly discuss the possible generation mechanisms for the ESWs associated with the main phase onset of the 24 August 2005 super-substorm based on data from other Cluster instruments and from various other satellites, thus providing a link to the super-substorm itself.