Deriving Global Convection Maps From SuperDARN Measurements
Deriving Global Convection Maps From SuperDARN Measurements
复制标题
从 SuperDARN 测量得出全球对流图
DOI：
10.1002/2017ja024543
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
R. Barnes
中科院分区：
文献类型：
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作者：
J. Gjerloev;C. Waters;R. Barnes
本文介绍了一种新的确定全球电离层对流的统计模拟技术。基于主成分回归（PCR）的技术基于超级双极光雷达网（SuperDARN）观测，是沃茨等人（https//：doi.org.10.1002/2015JA021596）用于SuperMAG数据的PCR技术的高级版本。虽然SuperMAG地面磁场扰动是矢量测量，但SuperDARN提供电离层对流的视线测量。每个视线流都有一个已知的方位角（或方向），必须转换为实际的矢量流。然而，垂直于方位角方向的分量是未知的。我们的方法使用来自SuperDARN数据库和PCR的历史数据来确定任何给定世界时的填充模型对流分布。填充数据过程由状态描述符列表（磁指数和太阳天顶角）驱动。最终的解决方案，然后从球冠谐波拟合SuperDARN测量和填充模型。与标准的SuperDARN填充模型相比，我们发现我们的填充模型提供了改进的解，并且最终解与SuperDARN测量结果更一致。我们的解决方案远不如标准SuperDARN解决方案动态，我们将其解释为由于标准SuperDARN技术中缺乏磁层-电离层惯性和通信延迟，而它本身就包含在我们的方法中。相反，我们认为磁层-电离层系统具有惯性，可以防止全球对流突然改变以响应行星际磁场的变化。
A new statistical modeling technique for determining the global ionospheric convection is described. The principal component regression (PCR)‐based technique is based on Super Dual Auroral Radar Network (SuperDARN) observations and is an advanced version of the PCR technique that Waters et al. ( , https//:doi.org.10.1002/2015JA021596) used for the SuperMAG data. While SuperMAG ground magnetic field perturbations are vector measurements, SuperDARN provides line‐of‐sight measurements of the ionospheric convection flow. Each line‐of‐sight flow has a known azimuth (or direction), which must be converted into the actual vector flow. However, the component perpendicular to the azimuth direction is unknown. Our method uses historical data from the SuperDARN database and PCR to determine a fill‐in model convection distribution for any given universal time. The fill‐in data process is driven by a list of state descriptors (magnetic indices and the solar zenith angle). The final solution is then derived from a spherical cap harmonic fit to the SuperDARN measurements and the fill‐in model. When compared with the standard SuperDARN fill‐in model, we find that our fill‐in model provides improved solutions, and the final solutions are in better agreement with the SuperDARN measurements. Our solutions are far less dynamic than the standard SuperDARN solutions, which we interpret as being due to a lack of magnetosphere‐ionosphere inertia and communication delays in the standard SuperDARN technique while it is inherently included in our approach. Rather, we argue that the magnetosphere‐ionosphere system has inertia that prevents the global convection from changing abruptly in response to an interplanetary magnetic field change.