Response Functions of the Ultraviolet Filters of TRACE and the Detectability of High-Frequency Acoustic Waves
Response Functions of the Ultraviolet Filters of TRACE and the Detectability of High-Frequency Acoustic Waves
复制标题
TRACE 紫外线滤光片的响应函数和高频声波的可检测性
DOI：
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
M. Carlsson
中科院分区：
文献类型：
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作者：
A. Fossum;M. Carlsson
我们已经使用了详细的非LTE辐射流体动力学模拟，以调查与过渡区和日冕探测器（TRACE）的高频声波的可探测性。将宽谱声波输入模型大气下边界的计算域，并通过将导出的强度与1700和1600滤波器的TRACE滤波器传输函数折叠来计算TRACE UV连续谱强度。功率谱，相图，和强度响应函数的计算，并导出强度形成高度。模拟表明，1700和1600通带的平均响应高度分别为360和430 km，宽度分别为325和185 km。TRACE强度响应函数的宽度大大降低了强度振荡的功率，但是如果波的功率足以对色球层的能量平衡产生重要影响，那么在没有仪器噪声的情况下，它们应该至少在40 mHz以下是可检测的，特别是在1600通带中。合成的1600和1700 TRACE强度之间的相位差遵循传播高达15 mHz的声波的预期曲线。对于更高的频率，相位差减小并且在相干性下降之前接近零，类似于观察到的行为。这可以通过1700个强度的响应函数的双峰性质来解释。
We have used detailed non-LTE radiation hydrodynamic simulations to investigate the detectability of high-frequency acoustic waves with the Transition Region And Coronal Explorer (TRACE). A broad spectrum of acoustic waves are fed into the computational domain at the lower boundary of the model atmosphere, and TRACE UV continuum intensities are calculated by folding the derived intensities with the TRACE filter transmission functions for the 1700 and 1600 filters. Power spectra, phase diagrams, and intensity response functions are calculated, and intensity formation heights are derived. The simulations show that the average response height of the 1700 and 1600 passbands are 360 and 430 km, with widths of 325 and 185 km. The width of the TRACE intensity response functions reduces the power of the intensity oscillations considerably, but if waves are present with power enough to be of importance for the energy balance of the chromosphere, they should be detectable at least up to 40 mHz in the absence of instrumental noise, especially in the 1600 passband. The phase difference between the synthesized 1600 and 1700 TRACE intensities follows the curve expected for propagating acoustic waves up to 15 mHz. For higher frequencies the phase difference decreases and approaches zero before the coherence drops down, similar to the observed behavior. This is explained by the double-peaked nature of the response function for the 1700 intensities.