搜索到2805篇“ PMSE“的相关文章
Exploring the occurrence rate of PMSE-Es by Digisonde at Tromsø
2021年
Polar mesosphere summer echoes(PMSE)are observed simultaneously with Digisonde and EISCAT VHF radar.The phenomenon of irregular Es layers is called PMSE-like or PMSE-Es(Polar Mesosphere Summer Echoes-Es)and has some relationship with real PMSE.In this paper,the characteristics of irregular Es layers at 80–100 km were observed by Digisonde at Tromsøduring 2003–2014 are statistically analyzed with ionograms.The diurnal,day-to-day and year-to-year variations and discrepancies of occurrence rate between PMSE and PMSE-Es are compared with the statistical results observed by Esrange MST radar(ESRAD),and the reasons are discussed.The results show that the trends in the occurrence rate of PMSE-Es are similar to the trends in the occurrence rate of PMSE,but there are some notable differences.The occurrence rate of PMSE-Es is much lower than the occurrence rate of PMSE.The minimum value of PMSE-Es appears 1–2 hours earlier than the minimum value of the PMSE occurrence rate,while PMSE-Es appear earlier than PMSE in the year.In addition,there is a significant positive correlation between the annual average occurrence rates of PMSE and PMSE-Es.PMSEEs is a relatively important occurrence in the polar mesopause.Analysis of its characteristics can provide new ideas and methods for studying the formation mechanism of PMSE.
HaiLong LiShuCan GeLin MengMaoYan WangAbdur RaufSafi Ullah
关键词:DIGISONDE
Investigation of PMSE echoes characteristics using the discontinuous EISCAT UHF observation and its relation with space environment被引量:1
2019年
The observations of Polar Mesosphere Summer Echoes (PMSE) were carried out using the sporadic data of EISCAT UHF radar during the summer season from 2004 to 2015. There were 25 h of PMSE echoes with EISCAT UHF radar. PMSE echoes were mostly observed only during the early morning and fore-noon time. Moreover, the PMSE echoes are positively correlated with Lymanα radiation, but the correlation is non-significant. The occurrence of PMSE echoes in the early morning and fore-noon time and there positive correlation with Lymanαradiation suggests that solar radiations might be one important factor for PMSE echoes in this study. Very weak positive, but statistically non-significant correlation is found between PMSE occurrence rate and the local geomagneticK-indices. It is found that there is a matching between the variation in the occurrence rate of PMSE and noctilucent clouds (NLC) up to some extent and they are positively correlated. This positive correlation might support the earlier proposed idea about the role of ice particle size in producing PMSE echoes at higher frequencies.
Abdur RAUFLI HailongSafi ULLAHWANG MaoyanMENG Lin
关键词:PMSEECHOESGEOMAGNETICEISCATUHF
PMSE dependence on frequency observed simultaneously with VHF and UHF radars in the presence of precipitation被引量:1
2018年
Using PMSE (polar mesosphere summer echoes) observations in combination with particle flux measurements obtained with detectors onboard the Geostationary Operational Environmental Satellite (GOES) a special condition is shown for the occurrence of rare observed UHF PMSE. When electron flux observed from GOES satellites show a decrease, then after being in the presence of precipitation UHF PMSE occurs. The heating effect on PMSE is small when the UHF electron density is enhanced at 90 km due to particle precipitation. We analyzed and compared the frequency dependence of PMSE under the condition of high energy particle precipitation in July of 2004 and 2007 at well separated frequencies (224 and 930 MHz) at the same site, height, and time. The frequency index varies with height and time. At different heights, the maximum as well as the minimum value of volume reflectivity at VHF is greater than that at UHF with 2 to 3 orders of magnitude. A new qualitative method for the analysis of dust distribution is used by analyzing the relationship between volume reflectivity and frequency index. In agreement with the results of the model it is shown that dust particles of smaller size generally did not occur at the edges, instead they occurred in the middle PMSE regions.
Safi ULLAHHailong LIAbdur RAUFLin MENGBin WANGMaoyan WANG
挪威地区甚高频雷达观测极区夏季中层回波被引量:1
2013年
于2010年7月13日至16日正午前后在挪威Troms地区(69.6°N)使用224MHz甚高频非相干散射雷达对极区夏季中层回波(PMSE)进行了观测.雷达几乎每天都捕捉到了PMSE现象,且其时常具有双层结构.为专门研究PMSE方向敏感性,采用了转动雷达发射波束指向的观测模式.对于13日的高PMSE层,回波功率随波束天顶角的增大而衰减,回波半宽角为8.9°.然而,对于13日的低PMSE层和14—15日的PMSE层,回波功率与波束指向基本无关,这与国际上早期使用约50MHz甚高频雷达观测的结果不一致.
马征征徐彬吴军许正文吴健
PMSE规律性及形成机制相关理论综述
2012年
介绍了PMSE相关现象及其研究的重要意义。阐述了PMSE的一些变化规律、极区中层大气环境及分层结构。评述了PMSE形成机制相关理论存在的一些问题,提出了研究PMSE的新途径。
李学良陈惠敏石雁祥
关键词:PMSE分层结构
Evolution of Small Scale Density Perturbations of Plasma and Charged Aerosol Particles in Polar Mesospheric Summer Echoes (PMSE) Layers
2011年
Time evolution of ionospheric D-region plasmas including the perturbations of electrons and charged aerosol particles is investigated under the conditions of polar mesosphere summer echoes (PMSE). It is shown that the time scale of decay of the electron density is in the order of an hour under typical PMSE conditions, in the majority of cases, the electron density is anticorrelated to the ion density, except that the radius of aerosol particles is greater than 50 nm. Also, the evolutions under varied parameters, such as the amplitude and width of perturbation, the aerosol particle radius, and the altitude of the PMSE occurrence are investigated. The obtained results are useful for interpreting the experimental observations.
胡祖权陈银华郑聚高刘昊郁明阳吴剑
关键词:PLASMAEVOLUTION
PMSE人工电子加热和过冲实验的初步研究被引量:5
2010年
极区中层夏季回波(PMSE)是发生在极区中层顶附近的一种异常强大的雷达回波,它具有明显的分层现象,加热有时能引起过冲现象.电波环境特性及模化技术国家重点实验室从2006年开始开展PMSE加热实验,通过三年的PMSE观测及加热实验,观察到PMSE回波强度具有明显的分层现象,并且层数之间变化迅速.另外本文也得到PMSE加热特征曲线OCC(Overshoot Characteristic Curves)图,回波功率随高度变化的剖面图、回波强度随时间的变化图,存在明显的过冲现象.本文开展的PMSE加热实验研究,为将来我国独立开展PMSE研究打下了一定的基础.
李海龙王茂琰吴健吴军徐彬黄际英
关键词:过冲尘埃等离子体
GPS信号在极区中层顶PMSE尘埃层的衰减分析被引量:1
2010年
极区中层夏季回波(PMSE,Polar Mesosphere Summer Echoes)是通过雷达在高纬当地夏季中层顶附近探测到的异常强大雷达回波,发生PMSE现象的区域属于尘埃等离子体范畴,现在已经在1290 MHz处用雷达观测到PMSE现象。GPS系统卫星的L2频率为1227.60 MHz,容易受到PMSE尘埃层的影响。GPS信号穿越极区中层顶时,其中的尘埃等离子体区域必然对信号产生影响。利用分层媒质方法结合ECT-02实验数据研究GPS系统L2载波信号经过尘埃层的吸收系数和信号的衰减程度,证实PMSE尘埃层能影响GPS通信。
李海龙吴健王茂琰黄际英
关键词:全球定位系统尘埃等离子体
电磁兼容性与无线频谱事务(ERM).PMSE技术频谱接入系统的操作方法和原则以及在选定频段上采用认知干扰缓解技术的高音质保证
关键词:电磁兼容ERMPMSE
ESR IPY观测与PMSE现象研究
极区电离层通过对流电场、粒子沉降和场向电流与磁层紧密耦合在一起,在太阳风-磁层-电离层以及热层耦合过程中起着重要作用。而试验观测可以获得较为全面、准确的空间科学数据,加速人们对电离层的认识,这对于深入研究电离层物理过程以...
杨李
关键词:电磁波传播极区电离层非相干散射
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