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arXiv 1908.03950astro-ph.SR
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SDO/HMI多普勒时距反演方法的比较

Comparison of time-distance inversion methods applied to SDO/HMI Dopplergrams

David Korda, Michal Švanda, Junwei Zhao

备注：
14 pages, 15 figures
发表信息：
A&A 629, A55 (2019)
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摘要：

我们比较的结果从JSOC管道的水平流分量和扰动的声速在一组深度与等效的结果从一个独立实施的管道使用不同的时间-距离反演方案。我们的反演管道允许一次反演所有量，同时允许最小化它们之间的串扰。这使我们有机会讨论JSOC数据产品中可能存在的偏差。在测试中，我们使用了减法最佳局部平均（SOLA）方法，最大限度地减少了串扰。我们比较了三个测试反演的每个数量在每个目标深度。首先，我们使用JSOC设置来重现JSOC结果。随后，我们使用了扩展的管道，以改善这些结果，包括更多的独立旅行时间测量，但保持JSOC指示的本地化在太阳。最后，我们使用本地化内核与JSOC元数据中的属性来反转流组件和声速扰动。我们成功地再现了水平流分量。JSOC产品中的高水平串扰强烈影响声速扰动。这导致声速扰动反演中的较大幅度。当使用定位在目标深度周围的目标函数时，获得了不同的结果。这是非局部化JSOC平均内核的结果。我们补充说，我们的方法也允许反演的垂直流。

英文摘要：

We compared the results from the JSOC pipeline for horizontal flow components and the perturbations of the speed of sound at set of depths with equivalent results from an independently implemented pipeline using a different time-distance inversion scheme. Our inversion pipeline allows inversion for all quantities at once while allowing minimisation of the crosstalk between them. This gives us an opportunity to discuss the possible biases present in the JSOC data products. For the tests we used the subtractive optimally localised averaging (SOLA) method with a minimisation of the cross-talk. We compared three test inversions for each quantity at each target depth. At first, we used the JSOC setup to reproduce the JSOC results. Subsequently, we used the extended pipeline to improve these results by incorporating more independent travel-time measurements but keeping the JSOC-indicated localisation in the Sun. Finally, we inverted for flow components and sound-speed perturbations using a localisation kernel with properties advertised in the JSOC metadata. We successfully reproduced the horizontal flow components. The sound-speed perturbations are strongly affected by the high level of the cross-talk in JSOC products. This leads to larger amplitudes in the inversions for the sound-speed perturbations. Different results were obtained when a target function localised around the target depth was used. This is a consequence of non-localised JSOC averaging kernels. We add that our methodology also allows inversion for the vertical flow.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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