Investigation of the Causes of the Longitudinal and Solar Cycle Variation of the Electron Density in the Bering Sea and Weddell Sea Anomalies
Investigation of the Causes of the Longitudinal and Solar Cycle Variation of the Electron Density in the Bering Sea and Weddell Sea Anomalies
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DOI：
10.1029/2018ja025413
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发表时间：
2018-09
期刊：
影响因子：
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通讯作者：
P. Richards;R. Meier;Shih‐Ping Chen;P. Dandenault
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文献类型：
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作者：
P. Richards;R. Meier;Shih‐Ping Chen;P. Dandenault
本文研究并量化了位于60°N附近18 ~ 151°E的6个电离层探空仪观测到的电离层峰值电子密度的纵向、太阳周期和日变化。该区域内嵌有白令海异常（BSA），其中夏季午夜峰值电子密度超过正午峰值电子密度。BSA是阿拉斯加以西的一个地区，最宽处从地理经度约100°到200°，地理纬度约55°到70°。通过将物理模型与20世纪70年代和80年代的电离层探空仪数据进行比较，发现中性风和中性密度的纵向变化是60°N附近18°E至151°E之间电子密度变化的最可能解释。磁偏角和磁倾角的纵向差异很小，对电子密度行为的影响可以忽略不计。我们对BSA的定义和行为类似于威德尔海异常（WSA），威德尔海异常是南半球的一个区域，夏季午夜峰值电子密度也超过正午峰值电子密度。虽然整个BSA的电子密度比WSA小2倍，但这两个异常在午夜和中午的电子密度比相似。随着太阳活动的增加，BSA变强，而WSA变弱。还证明了在电离层模型中包含振动激发的N2对于产生观测到的午夜到正午电子密度比至关重要。
This paper investigates and quantifies the longitudinal, solar cyclical, and diurnal variation of the ionosphere peak electron density observed by six ionosondes located between 18 and 151°E near 60°N. Embedded within this region is the Bering Sea anomaly (BSA) where the midnight peak electron density exceeds the midday peak electron density in summer. The BSA is a region West of Alaska extending from approximately 100° to 200° east geographic longitude and 55° to 70° north geographic latitude at its widest. By comparing a physical model with ionosonde data from the 1970s and 1980s, it is found that longitudinal changes in the neutral winds and neutral densities are the most likely explanation for the electron density variation between 18 and 151°E near 60°N. Longitudinal differences in magnetic declination and inclination are small and have a negligible effect on the electron density behavior. Our definition of and the behavior of the BSA are analogous to the Weddell Sea anomaly (WSA), a region in the Southern Hemisphere where the midnight peak electron density also exceeds the midday peak electron density in summer. Although the overall BSA electron density is a factor of 2 smaller than that in the WSA, the two anomalies have similar midnight to midday electron density ratios. It is found that the BSA gets stronger with increasing solar activity, while the WSA gets weaker. It is also demonstrated that including vibrationally excited N2 in an ionosphere model is crucial for producing the observed midnight to midday electron density ratios.