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Assimilation of GNSS Measurements for Estimation of High‐Latitude Convection Processes
Space Weather ( IF 3.8 ) Pub Date : 2020-08-25 , DOI: 10.1029/2019sw002409
Daniel S. Miladinovich 1 , Seebany Datta‐Barua 1 , Aurora López Rubio 1 , Shun‐Rong Zhang 2 , Gary S. Bust 3
Affiliation  

Geomagnetic storms produce significant electrodynamics at midlatitudes. Strong ion convection can affect thermospheric neutral wind motion. The converse is also true, such that both fields and winds can drive ionospheric plasma movement. This work adjusts a background modeled high‐latitude electrostatic potential to estimate the storm time electric field based on data‐derived plasma densities and measurements of neutral wind. Electron densities are derived from global navigation satellite system (GNSS) total electron content measurements using Ionospheric Data Assimilation Four‐Dimensional (IDA4D). These are input to Estimating Model Parameters from Ionospheric Reverse Engineering (EMPIRE) to estimate electric potential corrections to the background Weimer 2000 potential model. The EMPIRE basis functions for electric potential are spherical harmonics in dipole magnetic colatitude and longitude, enforced to be constant along a magnetic field line. For the 17 March 2015 storm, EMPIRE electric potential produces westward zonal ion drifts that more closely agree with incoherent scatter radar (ISR) measurements made at Millstone Hill than the background Weimer 2000 model alone, when electric potential and meridional neutral winds are both corrected. Additionally ingesting northward line‐of‐sight neutral wind measurements from a Fabry‐Perot interferometer at Millstone Hill makes little difference in the agreement between zonal ion drift predictions and measurements. Estimation of only electric potential reduces the agreement between the assimilated prediction of the field‐perpendicular zonal drifts and ISR measurements significantly.

中文翻译:

同化GNSS测量值以估算高纬度对流过程

地磁风暴在中纬度产生重要的电动力学。强离子对流会影响热层中性风运动。反之亦然,磁场和风都可以驱动电离层等离子体运动。这项工作基于数据衍生的等离子体密度和中性风的测量值,调整了背景建模的高纬度静电势,以估算风暴时间电场。电子密度是使用电离层数据同化四维(IDA4D)从全球导航卫星系统(GNSS)的总电子含量测量得出的。这些输入到电离层反向工程(EMPIRE)的“估计模型参数”中,以估计对背景Weimer 2000势模型的电势校正。电位的EMPIRE基函数是偶极子磁整经度中的球谐函数,强制沿磁场线保持恒定。对于2015年3月17日的暴风雨,EMPIRE电势会产生向西的纬向离子漂移,这与在单独对电势和子午经向风进行校正的情况下,与单独的背景Weimer 2000模型相比,在Millstone Hill进行的非相干散射雷达(ISR)测量更加吻合。此外,从Millstone Hill的Fabry-Perot干涉仪获取北视线中性风测量值,在区域离子漂移预测和测量值之间的一致性上几乎没有区别。
更新日期:2020-08-25
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