Observations of bow shock and magnetopause crossings from geosynchronous orbit on 31 March 2001
Observations of bow shock and magnetopause crossings from geosynchronous orbit on 31 March 2001
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2001 年 3 月 31 日从地球同步轨道观测到的弓激波和磁层顶穿越
DOI：
10.1029/2001ja000284
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发表时间：
2002
影响因子：
--
通讯作者：
N. Maynard
中科院分区：
文献类型：
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作者：
D. Ober;M. Thomsen;N. Maynard
[1]2001年3月31日，行星际磁场强度和太阳风动压的显著增强将磁层顶和弓形激波推入地球同步轨道。本文介绍了利用地球同步卫星1994-084上的磁层等离子体分析仪在当地中午附近观测到的无激波太阳风。地球同步卫星1991-080、1994-084和LANL-01 A在昼侧磁层的大部分区域间歇性地观测到磁鞘。中午附近的地球同步轨道上观测到的弓形激波和磁层顶的位置与理论的比较是合理的协议。利用几乎同时观测的磁层顶和弓形激波的位置在0451 UT，我们已经测试了模型的磁鞘的厚度和耀斑的磁层顶在那个时候。使用最小耀斑的磁层顶模型，估计的磁鞘厚度将比Spreiter等人[1966]的气体动力学解或凯恩斯和里昂[1996]的MHD模拟所预测的厚。或者，将磁层顶的位置置于磁层的鼻端，使之与凯恩斯和里昂[1996]的磁鞘厚度一致，需要比目前经验模型中磁层侧翼的耀斑更小。这些模型也很难预测其他观测到的远离当地中午的磁层顶穿越，这显然是由于模型在这一天的条件下过度燃烧。
[1] On 31 March 2001, significant enhancements in both the strength of the interplanetary magnetic field and the solar wind dynamic pressure pushed the magnetopause and bow shock inside of geosynchronous orbit. We present here observations of the unshocked solar wind observed with the Los Alamos magnetospheric plasma analyzer on geosynchronous satellite 1994-084 near local noon. The magnetosheath was observed intermittently at geosynchronous satellites 1991-080, 1994-084, and LANL-01A, across much of the dayside magnetosphere. Comparisons with theory of the observed bow shock and magnetopause locations at geosynchronous orbit near noon are in reasonable agreement. Using nearly simultaneous observations of the magnetopause and bow shock locations at 0451 UT, we have tested models for the thickness of the magnetosheath and flaring of the magnetopause at that time. Using the least flared of the magnetopause models, the estimated thickness of the magnetosheath would be thicker than would be predicted by either the gas dynamic solution of Spreiter et al. [1966] or the MHD simulations of Cairns and Lyon [1996]. Alternatively, placing the location of the magnetopause at the nose of the magnetosphere in conformance with the thickness of the magnetosheath from Cairns and Lyon [1996] requires less flaring on the flanks of the magnetosphere than currently present in the empirical models. The models also have difficulty predicting the other observed magnetopause crossings far from local noon apparently due to excessive flaring of the models for the conditions on this day.