【摘要】 利用美国NOAA和澳大利亚IPS提供的foF2实测数据,研究中国低纬地区foF2数据缺失的分布特征以及产生缺失的相关原因.结果表明:(1)foF2缺失是一个夜间现象,白天的缺失远比晚上少,并且在夏季的6或7月份的缺失最多、春秋季月份缺失较多、冬季月份则较少;(2)从一个太阳周期变化上看,foF2的缺失与太阳黑子数有着相反的变化规律,即太阳黑子数越高foF2的数据缺失越少,反之则越高.(3)foF2晚上时段的缺失在午夜前和午夜后的分布有明显不同,表现为夏季时段,午夜后的缺失占据主导;而在春秋季节,则表现为午夜前的缺失占据主导.通过分析研究,我们得到的结论是晚间foF2缺失的直接原因是扩展F层的出现所造成,并且不同类型的扩展F层造成的缺失分布也会不一样.统计表明,晚间foF2缺失与扩展F层的相关系数高达0.93.本文第一次从数据缺失上,对中国低纬地区foF2实测数据进行研究,得到比较完整的缺失分布特征,并给出了产生缺失的原因,可能对以后的研究有一定的参考意义.更多还原

【Abstract】 By using the observed data of foF2 from NOAA and IPS,we find that the distribution of missed-foF2 observations over China sector as follows:(1)the missed-foF2 observations is a nighttime phenomenon.The occurrence of missed-foF2 observations at night far outweighed those during daytime,especially in the equinoctial and summer months.(2)The occurrence of missed-foF2 observations has an inverse relationship with solar activity.During quiet solar activity periods, there is more the occurrence of missed-foF2 observations than at other times,especially in the summer months.As solar activity enhance,the occurrence of missedfoF2 observations will reduce.When the solar activity reached the maximum in a solar cycle,it would be the minimum occurrence of missed-foF2 observations.(3)The distribution of missed-foF2 observations between pre-midnight and postmidnight are also different.Results show that during summer months,the percentage of missed-foF2 observations in the premidnight hours is higher;but during equinoctial months,the percentage of missed-foF2 observations in the post-midnight hours is higher than pre-midnight.The occurrence of missedfoF2 observations at night is strongly correlated with the occurrence of spread-F.The correlation between them is as high as 0.93.The plausible cause could be the occurrence of spread-F which in turn is responsible for the generation of the occurrence of missed-foF2 observations during the night.更多还原