Apparent geocenter oscillations in Global Navigation Satellite Systems solutions caused by the ionospheric effect of second order
Apparent geocenter oscillations in Global Navigation Satellite Systems solutions caused by the ionospheric effect of second order
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DOI：
10.1029/2008jb006099
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发表时间：
2010-03
影响因子：
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通讯作者：
K. Palamartchouk
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文献类型：
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作者：
K. Palamartchouk
[1]使用国际参考电离层（IRI2007）和国际地磁参考场（IGRF2005）模型来创建一个全球范围内的全球导航卫星系统（GNSS）站点位移模型，该模型是由于未建模的高阶电离层延迟在太阳活动周期的不同时间、季节和阶段造成的。结果表明，高阶电离层延迟的日变化和季节变化导致GNSS确定的地球图形几何中心的明显振荡。当卫星轨道固定并采用1度参数化时，半年分量的z向振荡幅度达到2.5 mm， 11年分量的振荡幅度达到3.5 mm。在对在上方飞行的星载接收机进行精确轨道确定时，如果不能考虑高阶电离层延迟，而地面基准网络位于电离层以下，将导致地面和空间段之间的偏差。这种随时间和地点变化的偏差可能给解释卫星测高和卫星重力任务的结果造成困难，因为轨道参数的系统偏差可以解释为地球物理过程的表现。在此基础上，建议在全球大地测量网的常规GNSS处理中引入二阶电离层延迟模型，特别是考虑到即将到来的太阳活动极大期。
[1] The international reference ionosphere (IRI2007) and International Geomagnetic Reference Field (IGRF2005) models are used to create a worldwide model of apparent Global Navigation Satellite Systems (GNSS) site displacements due to unmodeled higher-order ionospheric delays for different time, seasons, and phases of the solar activity cycle. It is shown that diurnal and seasonal variability of the higher-order ionospheric delays causes apparent oscillations of the geometric center of the Earth's figure as determined by GNSS. The amplitude of the oscillations in the z direction reaches 2.5 mm for the semiannual and 3.5 mm for 11 year components when satellite orbits are considered fixed and degree 1 parameterization is used. Failure to account for the higher-order ionospheric delay when performing precise orbit determination for space-borne receivers, flying above, while the ground-based fiducial network is located below the ionosphere, will result in biases between the ground and the space segment. Such biases, changing with time and location, can cause difficulties in interpretation of results from satellite altimetry and satellite gravity missions, as systematic biases in orbital parameters can be interpreted as manifestations of geophysical processes. On the basis of the results presented, it is recommended to introduce the modeling of the second-order ionospheric delay in routine GNSS processing for global geodetic networks, especially in view of the forthcoming solar activity maximum.