Macrostructure of geomagnetic bays

摘要: Evidence is presented that suggests geomagnetic bay disturbances occur in two stages. The onset of each stage accompanied by a Pi 2 micropulsation; the fact occurs almost synchronously over earth's surface allows this micropulsation to be used define bay. time lag between onsets stages ranges from about 10 30 minutes. delay suggested required for transfer information front magnetosphere region reconnection magnetotail. recognition first as precursor can facilitate high-resolution studies auroral phenomena.