【作者】 李海龙；

【导师】 黄际英； 吴健；

【作者基本信息】 西安电子科技大学 ， 无线电物理， 2006， 硕士

【摘要】 极区中层夏季回波是通过雷达在高纬中层顶附近探测到的异常强大雷达回波,是一种非常奇特的自然现象,自从1979年被Ecklund和Balsley发现以来已经引起了广泛的关注。同北半球极区中层夏季回波(PMSE)观测历史相比,对南半球PMSE的观测历史非常短,相关的了解仍然非常匮乏,这和在南半球缺少合适的雷达设备有关。为了进一步详细地研究南极洲PMSE现象,澄清南北半球PMSE出现率的差异,克服在南半球VHF雷达少的缺陷,选择其他合适的设备去研究南极洲PMSE是必不可少的。本文首先介绍了PMSE和测高仪的一些知识,PMSE发生的背景条件,展望了PMSE的研究前景。其次说明了对PMSE的观测频段现在已不仅仅局限在甚高频范围,已经扩展到中频、高频和超高频频段。虽然不同雷达的参数不尽相同,但仍能得到雷达体反射率对数和雷达观测频率对数成线性关系。不同频率的观测雷达对应的雷达体反射率差别巨大:雷达体反射率随观测频率的增加而急剧的下降。最后通过不同的雷达在不同的频段都发现极区中层夏季回波具有规律性变化。为了更好的研究南极洲PMSE出现率的变化,本文应用南极中山站数字式测高仪对PMSE进行研究,证实了在中频和高频频段可以观测到PMSE现象,并发现其出现率规律性变化,如:日变化、半日变化、季节性变化等等,和北半球观测到的结果非常相似。另外本文对南北极PMSE出现率的差异进行了初步的分析。这将可以对使南、北半球极区中层夏季回波进行系统地对比研究。更多还原

【Abstract】 Recently, considerable attention has been paid to the anomalously high power radar echoes from the mesosphere at high latitude in summer: the so-called polar mesosphere summer echoes(PMSE). Much research on PMSE has been done since they were first found by Ecklund and Balsley as a fascinating phenomenon in 1979. In contrast to the Arctic PMSE, observational history of the Antarctic PMSE is very short and our knowledge of them is still poor. It could be due to lack of VHF radar facilities suitable for the detection of PMSE. Further detailed investigations are required to clarify the characteristics of the Antarctic PMSE and estimate possible interhemispheric asymmetry of PMSE occurrence probability. However, A problem is that only a small number of appropriate radars have been operated in Antarctica. Alternative way of monitoring the Antarctic mesosphere is indispensable for more detailed analysis of PMSE.First, we introduce the basic knowledge of PMSE and dynasonde, the conditions PMSE occur and the applied future of PMSE is prospected.Second, today we observe PMSE with not only VHF bands but also MF,HF,UHF bands, By observing PMSE with different radars at different bands, we can gain the relations between radar frequency and volume reflectivity, the significant differences of the volume reflectivity have been found at VHF and UHF bands: the higher the radar frequency, the lower the volume reflectivity.Finally the variations of PMSE have been gained at different frequency bands. In the articles the Digisonde Portable Spunder-4(DSP-4) at Zhongshan Station Antarctica has been used to observe ionosphere. By analyzing the data coming from DSP-4, PMSE have been confirmed occur at Antarctica at MF and HF bands, The PMSE occurrence probability variation have also been found very similar with Arctic PMSE, such as: seasonal variation, diurnal variation, semidiurnal variation, latitudinal variation et al. Then we give some Preliminary Analysis about discrepancy of PMSE with Arctic PMSE. So all-around research on PMSE in Antarctica and Arctic can be done.更多还原