中文摘要：

在首届狮子座强流星雨国际联测期间，开展了多学科、多手段的狮子座和天龙座强流星雨及其灾害性空间天气事件的综合观测，并结合近半个世纪的（1957-2003年）狮子座、英仙座和天龙座强流星雨及其相关资料的综合分析，充分证实了非偶现的周期性强流星雨可导致灾害性空间天气事件的形成．下述结论亦得到初步证认：强流星雨形成机制；fbEs异常峰出现规律；对宇航安全的严重危害．文中还对彗星尘演化过程、宇宙尘暴出现和丢失规律及中纬区Es层宇宙尘维持机制作了讨论．

英文摘要：

During the first international joint observation for strong meteor shower we made multi-subject observations for Leonids and Draconids and their disaster space weather events by several methods. Combining the synthetical analysis of Leonids, Perseids and Draconids and their related data from 1957 to 2003, we sufficiently confirm that the periodic strong meteor showers can result in the formation of catastrophic space weather events. The following summing-up is confirmed basically： 1. The formation mechanism of the strong meteor shower There are meteoroids with high density and uneven distribution close the cometary nucleus, especially in the direction of opposite the Sun and backside of the nucleus. They can stretch 1-11 AU along the cometary orbit and 1-5 （×10-3 AU） cross the orbit. Therefore good displays of meteor shower （10-100 times as usual） or storms （103-104 times as usual） can occur when the Earth passes a high density meteoroid stream during the period of 3 years before and 5 years after the perihelion passage of the comet. During that period, bolides or shooting stars which are serious harmful to spaceflight security increase greatly to 3%～10%. This corrects the wrong point of view that the harmful micro-meteoroids to spaceflight security in period meteor showers are 〈 1g only. 2. The cosmic dust maintaining mechanism of long-life Es layer in mid-latitude area It is proved the life of Es layer increased greatly when most ions are long-life metal type ions （Fe^＋, Mg^＋……） which composite coefficient is much smaller than that of molecule type ions（O2^＋, NO^＋……）. The observation for about 50 years roughly approves that the blanketing frequency of Es layer （fbEs） abnormally increase in large area （〉 105 km^2） and lasting long time （〉 15 min） only when strong meteor shower occurred at night. It is not f, l and c type Es layer evolved from sequence Es layer. This shows that the cause of fbEs increase is that the ionosphere was bombarded by