Synthetic observations of internal gravity waves in the solar atmosphere
Synthetic observations of internal gravity waves in the solar atmosphere
复制标题
太阳大气内部重力波的综合观测
DOI：
10.1051/0004-6361/201936846
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发表时间：
2019
影响因子：
6.5
通讯作者：
Vigeesh
中科院分区：
文献类型：
--
作者：
Vigeesh
目的研究从真实的太阳大气数值模拟获得的合成观测中探测到的重力内波(IGW)的特性。方法使用CO5BOLD程序对太阳磁对流进行了四种不同的模拟。模拟了一种无磁场模型和三种磁场模型。后三种模型的初始垂直均匀磁场分别为10、50和100G，代表安静的太阳表面的不同区域。我们使用NICOLE程序计算了两条磁性不敏感的中性铁线Fe Iλλ5434？和5576？的所有模拟模型的合成谱图。为了研究重力内波的性质，我们对强度和多普勒速度进行了傅里叶分析，得出了KH−ω诊断图中的功率、相位和相干性。结果我们发现合成光谱中重力内波的特征与真实太阳的观测结果一致。在合成观测中，磁场对波谱的影响不像在数值模拟中那样明显。利用谱线得到的相位差与模拟得到的相位差有很大的不同。重力波区域中两个大气层之间的相位相干性与高度有关，并且随着观测层之间的传播距离而减小。在所研究的模式中，低层大气的位相相干性高于∼高度分离的显著水平，而色球层的位相相干性随平均磁通密度的不同而减小到∼100-200公里。微弱且对温度不太敏感的谱线可能更适合于探测内波，并准确地确定它们在太阳大气中的能量通量。
AimsWe study the properties of internal gravity waves (IGWs) detected in synthetic observations that are obtained from realistic numerical simulation of the solar atmosphere.MethodsWe used four different simulations of the solar magneto-convection performed using the CO5BOLD code. A magnetic-field-free model and three magnetic models were simulated. The latter three models start with an initial vertical, homogeneous field of 10, 50, and 100 G magnetic flux density, representing different regions of the quiet solar surface. We used the NICOLE code to compute synthetic spectral maps from all the simulated models for the two magnetically insensitive neutral iron lines Fe Iλλ5434 Å and 5576 Å. We carried out Fourier analyses of the intensity and Doppler velocities to derive the power, phase, and coherence in thekh−ωdiagnostic diagram to study the properties of internal gravity waves.ResultsWe find the signatures of the internal gravity waves in the synthetic spectra to be consistent with observations of the real Sun. The effect of magnetic field on the wave spectra is not as clearly discernible in synthetic observations as in the case of numerical simulations. The phase differences obtained using the spectral lines are significantly different from the phase differences in the simulation. The phase coherency between two atmospheric layers in the gravity wave regime is height dependent and is seen to decrease with the travel distance between the observed layers. In the studied models, the lower atmosphere shows a phase coherency above the significance level for a height separation of ∼400 km, while in the chromospheric layers it reduces to ∼100–200 km depending on the average magnetic flux density.ConclusionWe conclude that the energy flux of IGWs determined from the phase difference analysis may be overestimated by an order of magnitude. Spectral lines that are weak and less temperature sensitive may be better suited to detecting internal waves and accurately determining their energy flux in the solar atmosphere.
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影响因子：
6.5
作者：
D. C. Solana;L. B. Rubio;J. C. D. T. Iniesta
通讯作者：
J. C. D. T. Iniesta
影响因子：
2.8
作者：
K. Nagashima;B. Löptien;L. Gizon;A. Birch;R. Cameron;S. Couvidat;S. Danilovic;B. Fleck;R. Stein
通讯作者：
K. Nagashima;B. Löptien;L. Gizon;A. Birch;R. Cameron;S. Couvidat;S. Danilovic;B. Fleck;R. Stein
太阳色球层辐射阻尼磁重力波的模式转换
DOI：
--
发表时间：
2011
期刊：
影响因子：
--
作者：
M. Newington;P. Cally
通讯作者：
P. Cally
关于太阳光球层中的声波和重力波及其能量传输
DOI：
--
发表时间：
2011
期刊：
影响因子：
--
作者：
F. Kneer;N. B. González
通讯作者：
N. B. González
用 Na I D 线研究太阳光球层的温度和速度波动
影响因子：
6.5
作者：
M. T. Eibe;P. Mein;T. Roudier;M. Faurobert
通讯作者：
M. Faurobert