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首页> 外文期刊>Journal of Geophysical Research, A. Space Physics: JGR >Modeling the observed proton aurora and ionospheric convection responses to changes in the IMF clock angle: 2. Persistence of ionospheric convection
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Modeling the observed proton aurora and ionospheric convection responses to changes in the IMF clock angle: 2. Persistence of ionospheric convection

机译：模拟观察到的质子极光和电离层对流对IMF时钟角变化的响应：2.电离层对流的持续性

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摘要

We apply a numerical model of time-dependent ionospheric convection to two directly driven reconnection pulses during a 15-min interval of southward IMF on 26 November 2000. The model requires an input magnetopause reconnection rate variation, which is here derived from the observed variation in the upstream IMF clock angle, . The reconnection rate is mapped to an ionospheric merging gap, the MLT extent of which is inferred from the Doppler-shifted Lyman-α emission on newly opened field lines, as observed by the FUV instrument on the IMAGE spacecraft. The model is used to reproduce a variety of features observed during this event: SuperDARN observations of the ionospheric convection pattern and transpolar voltage; FUV observations of the growth of patches of newly opened flux; FUV and in situ observations of the location of the Open-Closed field line Boundary (OCB) and a cusp ion step. We adopt a clock angle dependence of the magnetopause reconnection electric field, mapped to the ionosphere, of the form E nosin4(/2) and estimate the peak value, E no, by matching observed and modeled variations of both the latitude, ΛOCB, of the dayside OCB (as inferred from the equatorward edge of cusp proton emissions seen by FUV) and the transpolar voltage ΦPC (as derived using the mapped potential technique from SuperDARN HF radar data). This analysis also yields the time constant τOCB with which the open-closed boundary relaxes back toward its equilibrium configuration. For the case studied here, we find τOCB = 9.7 ± 1.3 min, consistent with previous inferences from the observed response of ionospheric flow to southward turnings of the IMF. The analysis confirms quantitatively the concepts of ionospheric flow excitation on which the model is based and explains some otherwise anomalous features of the cusp precipitation morphology.
机译：我们在2000年11月26日向南向国际货币基金组织15分钟的间隔内，对两个直接驱动的重新连接脉冲应用了随时间变化的电离层对流的数值模型。该模型要求输入磁层顶重新连接速率变化，这是根据观测到的电离层对流速率变化得出的上游IMF时钟角为。重新连接率被映射到电离层合并间隙，IMLT航天器上的FUV仪器观察到，其MLT程度是根据新打开的场线上多普勒频移的Lyman-α发射推断出来的。该模型用于重现此事件期间观察到的各种特征：SuperDARN对电离层对流模式和跨极电压的观察; FUV观察新打开的助焊剂斑块的生长; FUV和原位观测的开-闭磁场线边界（OCB）的位置和尖顶台阶。我们采用映射到电离层的形式为E nosin4（/ 2）的磁层顶重新连接电场的时钟角度依赖性，并通过匹配观测到的和模拟的纬度ΛOCB的变化来估计峰值E no日间OCB（由FUV观察到的尖峰质子发射的赤道边缘推断出）和跨极电压ΦPC（由SuperDARN HF雷达数据使用映射电位技术得出）。该分析还产生了时间常数τOCB，开闭边界沿该时间常数向其平衡构型松弛。对于此处研究的情况，我们发现τOCB= 9.7±1.3分钟，这与先前从观察到的电离层流对IMF向南转弯的响应得出的推论一致。该分析定量地证实了该模型所基于的电离层流激励的概念，并解释了尖顶降水形态的其他异常特征。

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