太阳活动区R9077引起的强烈吸收事件

利用南极中山站的观测数据分析了太阳活动区R9077所引起的强烈吸收事件，其中2000年7月14日的太阳质子事件引起了持续3天多强烈的极盖吸收，同时，激烈的太阳活动使磁层处于极度扰动状态，磁层高能粒子沉降使许多持续时间较短的吸收峰叠加在极盖吸收背景之上，最突出的是7月1日的吸收增强事件，其最大值达26dB。这是自1997年2月中山站安装成像式宇宙噪声接收机以来观测到的最强的吸收，另一个较突出的吸收峰发生在14日1753UT前后，本文还讨论了产生这些吸收的原由。

THE INTENSE IONOSPHERIC ABSORPTIONS ASSOCIATED WITH R9077

Using the ground observation data at Zhongshan Station of Antarctica during July 13 to 17, 2000, the intense absorption events associated with the activities of the solar active region R9077 are analyzed. It was shown that an intense polar cap absorption event lasted more than 3 days, which was caused by the solar proton event accompanying the X5/3B major flare at 1024UT on 13 July The polar cap event started at about 1040 UT on July 14, and lased to bo 1940UT on July 17, with a typical day-night variation. At the same time, the intense solar activities extremely disturbed the magnetosphere, therefore aurora substorms occurred fre- quently. The energetic particle precipitation from the magnetotail caused several absorption spikes superimposing on the background of polar cap absorption. The distinct event is an absorption enhancement that started at about 0300 UT on 15th, reached its peak of 26dB around 0645 UT and recovered at about 1110 UT on the same day, which was the strongest absorption event observed at Zhongshan Station since the imaging riometer installed in February, 1997. Another outstanding ab- sorption spike with pulsation occurred at around 1753 UT on 14th, its peak reached 6 dB.