Global model of the F2 layer peak height for low solar activity based on GPS radio-occultation data
Global model of the F2 layer peak height for low solar activity based on GPS radio-occultation data
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DOI：
10.1016/j.jastp.2013.08.024
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发表时间：
2013-11
影响因子：
1.9
通讯作者：
V. Shubin;A. Karpachev;K. Tsybulya
中科院分区：
文献类型：
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作者：
V. Shubin;A. Karpachev;K. Tsybulya
本文根据GPS掩星观测资料，提出了一个低太阳活动期（F10.7A<80）电离层F2层高度极大值（hmF 2）的全球中值模型SMF 2（Satellite Model of the F2 layer）。该模型利用CHAMP（~100，000 hmF 2值）、GRACE（~ 70，000）和COSMIC（~ 2，000，000）卫星上的GPS接收器提供的数据。对数据进行预处理，以去除电子密度的绝对最大值位于F2区域之外的情况。地面电离层探测数据用于比较和验证。hmF 2的空间依赖性由Legendre函数展开来建模。作为世界时（UT）的函数的时间依赖性由傅立叶展开来描述。模型的输入为：地理坐标、月份和F10.7A太阳活动指数。该模式是为安静的地磁条件（Kр=1-2），典型的低太阳活动。SMF 2符合国际参考电离层模型（IRI）在这些地区，地面电离层探测器网络密集。模型之间的最大差异被发现在赤道带，在海洋和极冠。无线电掩星和数字探空仪数据与预测的SMF 2中值的标准差在所有季节都是10-16公里，而IRI-2012是13-29公里。平均相对偏差比IRI小3-4倍，3-4%比9- 12%。因此，所提出的dhmF 2模型比IRI-2012更准确。
We propose a global median model SMF2 (Satellite Model of theF2 layer) of the ionosphericF2-layer height maximum (hmF2), based on GPS radio-occultation data for low solar activity periods (F10.7A<80). The model utilizes data provided by GPS receivers onboard satellites CHAMP (~100,000hmF2 values), GRACE (~70,000) and COSMIC (~2,000,000). The data were preprocessed to remove cases where the absolute maximum of the electron density lies outside theF2 region. Ground-based ionospheric sounding data were used for comparison and validation. Spatial dependence ofhmF2 is modeled by a Legendre-function expansion. Temporal dependence, as a function of Universal Time (UT), is described by a Fourier expansion. Inputs of the model are: geographical coordinates, month andF10.7Asolar activity index. The model is designed for quiet geomagnetic conditions (Kр=1–2), typical for low solar activity.SMF2 agrees well with the International Reference Ionosphere model (IRI) in those regions, where the ground-based ionosonde network is dense. Maximal difference between the models is found in the equatorial belt, over the oceans and the polar caps. Standard deviations of the radio-occultation and Digisonde data from the predicted SMF2 median are 10–16 km for all seasons, against 13–29 km for IRI-2012. Average relative deviations are 3–4 times less than for IRI, 3–4% against 9–12%. Therefore, the proposedhmF2 model is more accurate than IRI-2012.