We propose and employ a novel empirical method for determining chromospheric plage regions, which seems to better isolate plage from its surrounding regions compared to other methods commonly used. We caution that isolating plage from its immediate surroundings must be done with care in order to successfully mitigate statistical biases that, for instance, can impact quantitative comparisons between different chromospheric observables. Using this methodology, our analysis suggests that 1.25 mm wavelength free-free emission in plage regions observed with ALMA/Band6 may not form in the low chromosphere as previously thought, but rather in the upper chromospheric parts of dynamic plage features (such as spicules and other bright structures), i.e., near geometric heights of transition region temperatures. We investigate the high degree of similarity between chromospheric plage features observed in ALMA/Band6 (at 1.25 mm wavelength) and IRIS/Si IV at 1393A. We also show that IRIS/Mg II h and k is not as well correlated with ALMA/Band6 as was previously thought, and we discuss the discrepancies with previous works. Lastly, we report indications for chromospheric heating due to propagating shocks supported by the ALMA/Band6 observations.

中文翻译：

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ALMA 和 IRIS 对太阳色层的观测。二、色球斑的结构和动力学

我们提出并采用了一种新的经验方法来确定色球斑块区域，与其他常用方法相比，该方法似乎更好地将斑块与其周围区域隔离开来。我们警告说，必须小心地将斑块与其周围环境隔离，以成功减轻统计偏差，例如，这些偏差会影响不同色球观测值之间的定量比较。使用这种方法，我们的分析表明，在用 ALMA/Band6 观察到的斑块区域中 1.25 mm 波长的自由发射可能不会像以前认为的那样在低色球层中形成，而是在动态斑块特征（例如针状体和其他明亮的结构），即接近过渡区温度的几何高度。我们研究了在 ALMA/Band6（1.25 毫米波长）和 IRIS/Si IV 中 1393A 中观察到的色球斑块特征之间的高度相似性。我们还表明 IRIS/Mg II h 和 k 与 ALMA/Band6 的相关性不如以前认为的那么好，我们讨论了与以前工作的差异。最后，我们报告了由于 ALMA/Band6 观测支持的传播冲击而导致色球加热的迹象。