Whistle and Hall Magnetic Field Associated with Near-Earth Magnetotail Reconnection Observed by Cluster

Abstract

During the period of 2001 2003, Cluster passed through the near-Earth magnetotail, and observed 14 magnetotail reconnection events. Simultaneously, Cluster observed electromagnetic wave associated with reconnection events. These 14 events can be classified into three categories: (1) Category 1: wave activities prior to and during reconnection event are observed, and Hall magnetic field are observed during reconnection event; (2) Category 2: whistler waves and the Hall magnetic field are observed during reconnection events; and (3) Category 3: wave activities prior to and during reconnection event are observed, and however Hall magnetic field are not observed during reconnection event. 8 events belong to Category 1, in which some observed waves are the right-hand polarized whistler. 2 events belong to Category 2, in which no wave is observed prior to reconnection events. Category 3 has 2 events as well. For all these 14 events, the strong whistler waves corresponded to Hall magnetic field, indicating that whistler waves were mainly excited in Hall magnetic regions.