Electric field variability associated with the Millstone Hill electric field model
Electric field variability associated with the Millstone Hill electric field model
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DOI：
10.1029/1999ja900463
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发表时间：
2000-03
影响因子：
--
通讯作者：
M. Codrescu;T. Fuller‐Rowell;J. Foster;J. Holt;S. J. Cariglia
中科院分区：
文献类型：
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作者：
M. Codrescu;T. Fuller‐Rowell;J. Foster;J. Holt;S. J. Cariglia
在高纬度的热层中，由于磁层施加的电势而产生的焦耳加热与电场（E场）的平方的平均值成正比。大多数理论焦耳加热计算只使用平均电场，导致加热与平均电场的平方成正比。计算电场平方的平均值需要了解与平均电场模型相关的电场变异性的统计特征。在本文中，我们提出了与Millstone Hill bin-average经验E场模式相关的变率[Foster et al. 1986]，并讨论了变率作为高层大气能量源的含义。我们重新整理了来自马萨诸塞州Millstone Hill的雷达等离子体漂移测量，将磁纬度和当地时间作为极光活动的函数，并计算了平均电场和与之相关的变化，反映在bin标准偏差中。我们给出了安静地磁条件和扰动地磁条件下四季的E场模式和相关变率。我们表明，对于一个电场模型具有高斯分布的小尺度变异性的平均值，平均场和变异性对焦耳加热的产生有相等的贡献。
Joule heating that is generated at high latitudes in the thermosphere because of the magnetospherically imposed electric potential is proportional to the average of the square of the electric field (E field). Most theoretical Joule heating computations use only average electric fields, resulting in heating that is proportional to the square of the average E field. The computation of the average of the square of the E field requires knowledge about the statistical characteristics of E field variability associated with the average electric field model. In this paper we present the variability associated with the Millstone Hill bin-averaged empirical E field model [Foster et al. 1986] and discuss the implications of variability as an upper atmosphere energy source. We rebinned the radar plasma drift measurements from Millstone Hill, Massachusetts, in magnetic latitude and local time as a function of auroral activity and calculated the average electric fields and the variability associated with them as reflected in the bin standard deviations. We present the E field patterns and the associated variability for both quiet and disturbed geomagnetic conditions for the four seasons. We show that for an electric field model with a Gaussian distribution of small-scale variability around the mean, the average field and the variability have equal contributions to Joule heating generation.