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Fig. 6.

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Spatially averaged Fe/S FIP bias at the loop top (orange filled dots) compared to the entire EIS field of view (empty dots), mimicking Sun-as-a-star observations. The loop top FIP biases are significantly higher compared to the full field of view averages. It is worth noting that one of the bright loop footpoint was located behind the limb for this X8.2 flare, and the first six rasters only covered the upper portion of the flare loops (as evidenced in the top six panels in Figure 1). Including the entire flare loop and both footpoints would likely further lower the full FOV averaged FIP bias. This comparison illustrates how spatially-averaged observations can mask localized high FIP bias features, potentially explaining why some Sun-as-a-star studies, particularly those using Fe and Si as low-FIP elements, have reported photospheric or weakly enhanced composition during flares.

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