MODEL OF EQUATORIAL SCINTILLATIONS FROM INSITU MEASUREMENTS
MODEL OF EQUATORIAL SCINTILLATIONS FROM INSITU MEASUREMENTS
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DOI：
10.1029/rs011i010p00821
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发表时间：
1976-01-01
期刊：
影响因子：
1.6
通讯作者：
KHAN, BK
中科院分区：
文献类型：
--
作者：
BASU, S;BASU, S;KHAN, BK
利用OGO-6卫星上的减速势分析仪在近地点高度400 km附近对F区不规则振幅和环境电子密度的现场测量，导出了赤道区电子密度偏差的变化规律。基于这些测量的电子密度偏差和其他假设的模型参数，包括一个三维的指数为4的不规则谱的幂律形式，赤道涡旋模型的衍射理论的框架内开发。本文导出了1969年11月至1970年12月期间1900-2300年LMT期间140 MHz上估计的≥ 4.5 dB的赤道振荡发生率等值线。该模型被发现描绘一个显着的经度变化与闪烁带的宽度和百分比发生最大的非洲部门。空间闪烁带的纬度范围在美国扇区变窄，而在印度和远东扇区的范围和发生的闪烁没有减少很多。从这个模型估计的闪烁发生的百分比被认为是一致的VHF闪烁测量在加纳，万卡约，加尔各答。此外，该模型被认为是在质量上与千兆赫观测在不同的地点由通信卫星组。在VHF，UHF和GHz的闪烁估计不同的模型参数的影响进行了讨论。的影响，所观察到的纵向变化的赤道不规则性形成的现有理论上的赤纬。
In-situ measurements of F-region irregularity amplitude and ambient electron density made by the retarding potential analyzer on OGO-6 near the perigee altitude of 400 km have been utilized to derive the variation of electron density deviation over the equatorial region. Based on these measured electron density deviations and other assumed model parameters including a three-dimensional power law form of irregularity spectrum with index 4, a model of equatorial scintillations is developed in the framework of diffraction theory. The percentage occurrence contours of estimated equatorial scintillations ≥ 4.5 dB at 140 MHz during 1900–2300 LMT for the period November–December 1969 and 1970 have been derived. The model is found to depict a pronounced longitude variation with the scintillation belt width and percentage occurrence being maximum over the African sector. The latitude extent of the spatial scintillation belt narrows over the American sector without much decrease in the scintillation occurrence whereas over the Indian and Far Eastern sectors both the extent and the occurrence are found to decrease. The percentage occurrence of scintillations estimated from this model is found to be consistent with VHF scintillation measurements at Ghana, Huancayo, and Calcutta. In addition, the model was found to be in qualitative agreement with GHz observations at various longitudes made by the COMSAT group. The effects of varying model parameters on scintillation estimates at VHF, UHF, and GHz are discussed. Implications of the observed longitudinal variation of scintillations on current theories of equatorial irregularity formation are indicated.