Sudden increase events occur at local midnight till dawn. There are no sudden increase phenomena from 10:00 to 18:00. But they are found after 18 :00. These features agree well with the observational data from the satellite.

• 突增事件是发生在地方时半夜到黎明,10点到18点这一时间内没有突增现象,18点以后又发现有突增现象。 这些主要特征与卫星的观测结果相符合。