摘要
Ⅰ. INTRODUCTIONAt 07h57m30s UT May 16, 1981 a great two-ribbon proton flare occurred in solar activity region. SESC 3106. At 08h48m UT, the flare reached maximum (area of the flare was about 1333. The unit is 10-6 of the solar semi-spheric area). The location of this flare was N12°, E14°, Carrington longitule 160°. It lasted about 2 hr. At the time
