Comparing high-latitude thermospheric winds from FPI and CHAMP accelerometer measurements
Comparing high-latitude thermospheric winds from FPI and CHAMP accelerometer measurements
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DOI：
10.5194/angeo-2019-57
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发表时间：
2019-04
影响因子：
1.9
通讯作者：
A. Aruliah;M. Förster;R. Hood;I. Mcwhirter;E. Doornbos
中科院分区：
文献类型：
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作者：
A. Aruliah;M. Förster;R. Hood;I. Mcwhirter;E. Doornbos
摘要。由于上层热层粘度大，一般认为水平风速与f1区（> - 300 km）以上的高度无关。这一假设用于比较两种完全不同的热层中性风观测方法，使用北半球高纬度的两个不同地点。测量数据来自地面法布里-珀罗干涉仪（FPI）和CHAMP卫星上的原位加速度计测量数据，CHAMP卫星位于近极轨道上。UCL KEOPS FPI位于瑞典基鲁纳附近ESRANGE站点的极光椭圆附近（67.8°N, 20.4°E）。伦敦大学学院朗伊尔城FPI是一个极地帽站点，位于斯瓦尔巴群岛（78.1°N, 16.0°E）的Kjell Henriksen天文台。比较是在统计意义上进行的，比较的是冬季月份（11月至1月）夜间获得的较长时间序列；CHAMP卫星于2001年至2007年在±2°（±220公里水平范围）的观测地点上空飞行。假设FPI测量的是约240 km高度，即原子氧630.0 nm发射的峰值发射高度沿风视距的多普勒频移。与CHAMP轨道成直角的风的组成是由高度上最先进的精密加速度计测量得出的。CHAMP的海拔高度在450公里（2001年）到330公里（2007年）之间；即比FPI风观测值高100-200公里。研究表明，高纬度地区的CHAMP风比FPI风大1.5-2倍。除了测试不同测量方法的一致性外，该研究还旨在阐明粘度对热层风高度依赖性的影响。
Abstract. It is generally assumed that horizontal wind velocities are independent of height above the F1-region (> 300 km) due to the large viscosity of the upper thermosphere. This assumption is used to compare two completely different methods of thermospheric neutral wind observation, using two distinct locations in the high-latitude Northern Hemisphere. The measurements are from ground-based Fabry-Perot Interferometers (FPI), and from in-situ accelerometer measurements onboard the CHAMP satellite, which was in a near polar orbit. The UCL KEOPS FPI is located in the vicinity of the auroral oval at the ESRANGE site near Kiruna, Sweden (67.8° N, 20.4° E). The UCL Longyearbyen FPI is a polar cap site, located at the Kjell Henriksen Observatory on Svalbard (78.1° N, 16.0° E). The comparison is done in a statistical sense, comparing a longer time series obtained during nighttime hours in the winter months (November to January); with overflights of the CHAMP satellite between 2001 and 2007 over the observational sites, within ±2° (±220 km horizontal range). The FPI is assumed to measure the Doppler shift along the line-of-sight of winds at ~ 240 km height, i.e. the peak emission height of the atomic oxygen 630.0 nm emission. The components of winds at right angles to the CHAMP orbit are derived from state-of-the-art precision accelerometer measurements at altitudes. CHAMP was at altitudes between 450 km (in 2001) to 330 km (in 2007); i.e. 100–200 km above the FPI wind observations. We show that CHAMP winds at high latitudes are systematically 1.5–2 times larger than FPI winds. In addition to testing the consistency of the different measurement approaches, the study aims to clarify the effects of viscosity on the height dependence of thermospheric winds.