Fig. 3From: Relationship between wave-like auroral arcs and Pi2 disturbances in plasma sheet prior to substorm onsetWave-like substorm auroral arc intensity as a function of longitude and time. The directions of westward and eastward are indicated at the top of the figure. One example of the westward movements is marked by dashed white arrow. The example of westward movement starts from 0401:00 to 0403:30 UTBack to article page