Extraction of solar and thermospheric information from the ionospheric electron density profile
Extraction of solar and thermospheric information from the ionospheric electron density profile
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DOI：
10.1029/2000ja000403
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发表时间：
2001-07
影响因子：
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通讯作者：
Shunrong Zhang;W. Oliver;S. Fukao;S. Kawamura
中科院分区：
文献类型：
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作者：
Shunrong Zhang;W. Oliver;S. Fukao;S. Kawamura
这项电离层电子密度 N-e 剖面同化的探索性研究涉及外层温度 T-ex、大气成分 [O] 和 [N-2]、经向热层风和太阳 EUV 通量的信息提取。这些参数用作电离层模型的输入变量，并一次调整一个、两个或三个，以使模型 N-e 剖面与实验 N-e 剖面最一致。讨论了多变量拟合中重要的模糊性/唯一性问题，该问题尚未在文献中得到解决。我们发现：（1）在单变量拟合中，任何测试的变量都可以成功调整以改善数据模型拟合，但派生变量的有效性通常取决于为固定参数选择的值的有效性。 (2) 单变量拟合的最佳拟合模型轮廓有时与测量轮廓有明显差异，表明多变量拟合是有必要的。多变量拟合通常会大大减少模型数据轮廓差异并改善导出参数的误差线。 (3)多变量拟合往往表现出较大的变量相关性，表明变量确定往往不唯一。 (4) 经向风往往与其他变量表现出较弱的相关性，这表明只要其他大气变量已知，就可以可靠地提取经向风和任何其他参数。 (5) [N-2] 通常与其他参数（风除外）表现出很强的相关性。 EUV 通量和 [O] 也显示出很大的相关性。 (6) T-ex-[O] 和 T-ex-EUV 对显示出中等到高度的相关性。 (7) 三变量拟合几乎总是在导出的参数中显示出很大的模糊性。
This exploratory study of ionospheric electron density N-e profile assimilation concerns the extraction of information on exospheric temperature T-ex, atmospheric composition [O] and [N-2], meridional thermospheric winds, and solar EUV flux. These parameters are used as input variables to an ionospheric model and adjusted, one, two, or three at a time, to bring the model N-e profile into best agreement with an experimental N-e profile. The important ambiguity/uniqueness issue in the multiple-variable fit, which has yet to be addressed in the literature, is discussed. We found the following: (1) In a single-variable fit, any variable tested may be adjusted successfully to improve the data-model fit, but the validity of the derived variable generally depends on the validity of the values chosen for the fixed parameters. (2) The best fit model profile from a single-variable fit sometimes shows clear differences from the measured profile, indicating that multiple-variable fitting is warranted. The multiple-variable fit often greatly reduces the model-data profile differences and improves the error bars on the derived parameters. (3) Multiple-variable fits often show large variable correlations, indicating that variable determination is often not unique. (4) The meridional wind often shows weak correlation with other variables, suggesting that the meridional wind and any other parameter can be reliably extracted, provided that the other atmospheric variables are known. (5) [N-2] often shows strong correlation with other parameters (except with the wind). The EUV flux and [O] also show large correlation. (6) The T-ex-[O] and T-ex-EUV pairs show medium to high correlation. (7) The three-variable fits nearly always show large ambiguities in the derived parameters.