Context. The use of instruments that record narrowband images at selected wavelengths is a common approach in solar observations. They allow scanning of a spectral line by sampling the Stokes profiles with two-dimensional images at each line position, but require a compromise between spectral resolution and temporal cadence. The interpretation and inversion of spectropolarimetric data generally neglect changes in the solar atmosphere during the scanning of line profiles. Aims. We evaluate the impact of the time-dependent acquisition of various wavelengths on the inversion of spectropolarimetric profiles from chromospheric lines during umbral flashes. Methods. Numerical simulations of nonlinear wave propagation in a sunspot model were performed with the code MANCHA. Synthetic Stokes parameters in the Ca II 8542 ? line in NLTE were computed for an umbral flash event using the code NICOLE. Artificial profiles with the same wavelength coverage and temporal cadence from reported observations were constructed and inverted. The inferred atmospheric stratifications were compared with the original simulated models. Results. The inferred atmospheres provide a reasonable characterization of the thermodynamic properties of the atmosphere during most of the phases of the umbral flash. The Stokes profiles present apparent wavelength shifts and other spurious deformations at the early stages of the flash, when the shock wave reaches the formation height of the Ca II 8542 ? line. These features are misinterpreted by the inversion code, which can return unrealistic atmospheric models from a good fit of the Stokes profiles. The misguided results include flashed atmospheres with strong downflows, even though the simulation exhibits upflows during the umbral flash, and large variations in the magnetic field strength. Conclusions. Our analyses validate the inversion of Stokes profiles acquired by sequentially scanning certain selected wavelengths of a line profile, even in the case of rapidly changing chromospheric events such as umbral flashes. However, the inversion results are unreliable during a short period at the development phase of the flash.
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机译：上下文。在太阳观测中，使用在特定波长下记录窄带图像的仪器是一种常见的方法。它们允许通过在每个线位置使用二维图像对Stokes轮廓进行采样来扫描光谱线，但是需要在光谱分辨率和时间节奏之间进行折衷。光谱极化数据的解释和反演通常忽略了在扫描线轮廓时太阳大气中的变化。目的我们评估了本影闪烁过程中，各种波长随时间变化的采集对来自色球层线的光谱极化轮廓反转的影响。方法。用代码MANCHA对太阳黑子模型中非线性波传播进行了数值模拟。 Ca II 8542的合成斯托克斯参数使用代码NICOLE计算了本影闪事件的NLTE线路。根据报告的观察结果，构造和反转具有相同波长覆盖范围和时间节奏的人工剖面。推断的大气分层与原始模拟模型进行了比较。结果。推断出的大气层在本影闪动的大多数阶段都提供了大气层热力学特性的合理表征。当冲击波达到Ca II 8542的形成高度时，斯托克斯曲线在闪光的早期呈现明显的波长偏移和其他杂散变形。线。这些特征被反演代码误解了，反演代码会从很合适的Stokes剖面返回不切实际的大气模型。错误的结果包括闪蒸的大气，具有强烈的下气流，即使该模拟在本影闪烁期间显示出上气流，并且磁场强度也存在较大差异。结论。我们的分析验证了通过顺序扫描线轮廓的某些选定波长获得的斯托克斯轮廓的反转，即使在快速变化的色球事件（如本影闪烁）的情况下也是如此。但是，在闪光灯的显影阶段，反转结果在短时间内是不可靠的。
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