Solitary waves observed in the auroral zone: the Cluster multi-spacecraft perspective - Pickett,JS; Kahler,SW; Chen,LJ; Huff,RL; Santolík,O; Khotyaintsev,Y; Décréau,PM; Winningham,D; Frahm,R; Goldstein,ML; Lakhina,GS; Tsurutani,BT; et al. (COPERNICUS GESELLSCHAFT MBH, 2004)