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首页> 外文期刊>Surveys in Geophysics: An International Review Journal of Geophysics and Planetary Sciences >GPS L1-Frequency Observations of Equatorial Scintillations and Irregularity Zonal Velocities
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GPS L1-Frequency Observations of Equatorial Scintillations and Irregularity Zonal Velocities

机译：GPS L1赤道闪烁和不规则区域速度的频率观测

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摘要

In this work, the climatology of ionospheric scintillations at global positioning system (GPS) L-band frequency and the zonal drift velocities of scintillation-producing irregularities were depicted for the equatorial observatory of S?o Luis (2.33°S; 44.21°W; dip latitude 1.3°S), Brazil. This is the first time that the hourly, monthly, and seasonal variations of scintillations and irregularity zonal drifts at S?o Luis were characterized during periods of different solar activity levels (from December 1998 to February 2007). The percentage occurrence of scintillations at different sectors of the sky was also investigated, and the results revealed that the scintillations are more probable to be observed in the west sector of the sky above S?o Luis, whereas the north–south asymmetries are possibly related to asymmetries in the plasma density distribution at offequatorial latitudes. The scintillations on GPS signals occurred more frequently around solar maximum years, but it is also clear from the results of a strong variability in the scintillation activity in the years with moderate solar flux during the descending phase of the solar cycle. The equatorial scintillations occur predominantly during pre-midnight hours with a broad maximum near the December solstice months. In general, weak level of scintillations (S_4 index between 0.2 and 0.4) dominated at all seasons; however, during the winter months around solar maximum years (although the scintillation occurrence is extremely low), stronger levels of scintillations (S_4>0.6) may occur at comparable rate with the weak scintillations. The irregularity zonal velocities, as estimated from the GPS spaced-receiver technique, presented a different scenario for the two seasons analyzed; during the equinoxes, the magnitude of the zonal velocities appeared not to change with the solar activity, whereas during the December solstice months, the larger magnitudes were observed around solar maximum years. Other relevant aspects of the observations are highlighted and discussed.
机译：在这项工作中，描述了圣路易斯赤道天文台（2.33°S; 44.21°W; 1987年;巴西，南纬1.3度）。这是首次在太阳活动水平不同的时期（1998年12月至2007年2月），对S？o Luis的闪烁和不规则区带漂移进行每小时，每月和季节性变化的特征分析。还研究了在不同天空区域发生闪烁的百分比，结果表明，更可能在圣路易斯上方天空的西部区域观察到闪烁，而南北不对称可能与在赤道纬度处的等离子体密度分布不​​对称。 GPS信号的闪烁在太阳最大年份附近更频繁地发生，但是从太阳活动的下降阶段中有中等太阳通量的年份中闪烁活动的强烈变化的结果也很明显。赤道闪烁主要发生在午夜前的几个小时，而至十二月的夏至月份则出现了极大的最大值。通常，在所有季节，闪烁水平都很弱（S_4指数在0.2到0.4之间）。但是，在太阳最大年份附近的冬季（尽管发生的闪烁非常少），可能会以与弱闪烁相似的速率发生更强的闪烁（S_4> 0.6）。根据GPS间隔接收器技术估算出的不规则纬向速度，为所分析的两个季节提供了不同的情景。在春分时，纬向速度的大小似乎没有随着太阳活动的变化而变化，而在12月的冬至月份中，在太阳最大年份附近观测到了较大的大小。观察结果的其他相关方面也得到强调和讨论。

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