Observations of the earth's polar cleft at large radial distances with the Hawkeye 1 magnetometer
Observations of the earth's polar cleft at large radial distances with the Hawkeye 1 magnetometer
复制标题
使用鹰眼 1 号磁力计对大径向距离的地球极裂进行观测
DOI：
10.1029/ja095ia12p20945
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发表时间：
1990
影响因子：
--
通讯作者：
J. A. Allen
中科院分区：
文献类型：
--
作者：
W. Farrell;J. A. Allen
基于364个航天器通过日侧区域的数据，利用鹰眼1号上的磁力计确定了大径向距离上的极裂位置。该数据集代表了在大径向距离上调查高纬度地区的最大数据集之一，使其成为研究尖峰和裂口地区的理想数据集。对裂缝的识别依赖于注意到该区域的磁场强度与偶极子场的磁场强度的强烈负偏差。在太阳磁坐标中，在纬度40{°}~ 70{°}和经度{正负}75{°}之间存在裂缝；在地心磁层坐标中，在纬度20{°}~ 75{°}和经度{正负}75{°}之间存在裂缝。150{度}的极端纵向范围比以前一些研究报告的要大。与裂缝相关的大型磁坳陷延伸至12r {sub E}。超过这一点，低模型偶极子场强使得基于磁凹陷的裂缝测定不可靠。在磁纬度和磁经度上，裂缝发生在一个椭圆形内，但这个椭圆形具有统计性质，不能被解释为该地区在给定时刻的形状。正如在更多其他研究中所报道的那样，在Kp较大和行星际磁场（IMF）指向南方的时期，与平静时期的几何形状相比，观测到裂缝向低纬度移动。当太阳风体积流速度V{sub sw}较大（>450 km/s）时，也观测到南移，当太阳风气压P{sub sw}较大时，该区域可能扩大。裂隙纬度随V{sub sw}和P{sub sw}的变化在以往的研究中尚未得到彻底的研究。«少
Based on 364-spacecraft passes through the dayside region, the position of the polar cleft at large redial distances was determined with the magnetometer flown on Hawkeye 1. This data set represents one of the largest to investigate the high-latitude region at large radial distances, making it ideal for the study of the cusp and cleft region. Identification of the cleft depended on noting strong negative deviations of the magnetic field strength in the region from that of the dipole field. In solar magnetic coordinates, cleft observations were found between 40{degree} and 70{degree} latitude and {plus minus}75{degree} longitude, while in geocentric magnetospheric coordinates, these observations were found between 20{degree} and 75{degree} latitude and {plus minus} 75{degree} longitude. The extreme longitudinal extent of 150{degree} is larger than those reported in some previous studies. Large magnetic depressions associated with the cleft extend out to 12 R{sub E}. Beyond this point, low model dipole field strengths make the determination of the cleft based on magnetic depressions unreliable. The cleft occurrences fall within an oval in magnetic latitude and longitude, but this oval is of a statistical nature and cannot be interpreted as the shape of the region at a given moment. As reported inmore » other studies, the cleft was observed to shift to lower latitudes as compared to its quiet time geometry during periods when Kp was large and when the interplanetary magnetic field (IMF) pointed in a southerly direction. A southerly shift was also observed when th solar wind bulk flow speed, V{sub sw}, was large (>450 km/s), and the region might have enlarged when solar wind pressure, P{sub sw}, was large. The variation of the cleft latitude with V{sub sw} and P{sub sw} has not been thoroughly examined in previous studies.« less