Validity Study of the Swarm Horizontal Cross-Track Ion Drift Velocities in the High-Latitude Ionosphere
Validity Study of the Swarm Horizontal Cross-Track Ion Drift Velocities in the High-Latitude Ionosphere
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DOI：
10.1029/2018ea000546
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发表时间：
2019-03-01
影响因子：
3.1
通讯作者：
Weimer, Daniel R.
中科院分区：
文献类型：
--
作者：
Lomidze, Levan;Burchill, Johnathan K.;Weimer, Daniel R.
高纬度电离层等离子体对流在决定陆地电离层的许多过程中发挥着重要作用。欧洲航天局三颗极轨 Swarm 卫星上的电场仪器使用热离子成像仪能量/到达角静电分析仪测量约 500 公里高度的电离层离子漂移速度。最近，欧洲航天局发布了这些漂移的水平跨轨分量，并在高纬度地区进行了校准。本文涉及 Swarm 水平交叉轨迹离子漂移测量的验证。使用2015年11月至2017年7月期间所有可用的Swarm-A和Swarm-B 2 Hz数据，构建并检查了高纬度离子对流的气候学。结果与分别在北半球和南半球不同行星际磁场和太阳风条件下从 Weimer 2005 经验对流电场模型获得的相应气候学进行了比较。离子漂移数据有时在中纬度地区表现出较大的偏移。然而，在使用偏移消除的改进对漂移进行重新校准后，Swarm 交叉轨迹离子漂移气候学在统计上与 Weimer 2005 模型相当一致，并且正确响应不断变化的地球空间环境。两个结果在约 200 m/s（均方根偏差）内一致，但向南的行星际磁场和北半球的相关性更高（r(swarm-A) = 0.84，r(swarm-B) = 0.77），其中 Swarm-A 和 Swarm-B 的相应漂移幅度分别比模型估计值大 14% 和 33%。修订后的 Swarm 水平跨轨漂移速度中看到的对流模式比使用该模型获得的对流模式更加结构化，但总体而言不存在显着的系统误差。
High-latitude ionospheric plasma convection plays a fundamental role in determining many processes in the terrestrial ionosphere. Electric Field Instruments on the European Space Agency's three polar-orbiting Swarm satellites measure ionospheric ion drift velocities at about 500 km altitude using thermal ion imager energy/angle-of-arrival electrostatic analyzers. Recently, European Space Agency released horizontal cross-track components of these drifts, calibrated at high latitudes. This paper concerns the validation of the Swarm horizontal cross-track ion drift measurements. All available Swarm-A and Swarm-B 2 Hz data between November 2015 and July 2017 were used and the climatology of high-latitude ion convection was constructed and examined. Results were compared to corresponding climatology obtained from the Weimer 2005 empirical convection electric field model under different interplanetary magnetic field and solar wind conditions in the northern and southern hemispheres, separately. The ion drift data sometimes exhibit large offsets at middle latitudes. However, following a recalibration of the drifts using a refinement of the offset removal, the Swarm cross-track ion drift climatology agrees reasonably well statistically with the Weimer 2005 model, and properly responds to the changing geospace environment. The two results agree within about 200 m/s (root-mean-square deviation), however the correlations are higher for southward interplanetary magnetic field and in the northern hemisphere (r(swarm-A) = 0.84, r(swarm-B) = 0.77), for which the corresponding magnitudes of Swarm-A and Swarm-B drifts are similar to 14% and similar to 33% larger than the model estimates, respectively. The convection patterns seen in the revised Swarm horizontal cross-track drift velocities are more structured than those obtained using the model, but overall no significant systematic errors are present.