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Fig. 3

image

Covariances averaged separately over the umbra, penumbra, and the quiet Sun analysis for the full Δ range. The top frame is for ν = 4.0 mHz and the bottom frame is for ν = 3.1 mHz. The first andsecond skip areas are averaged separately over Δ and then stitched together. In both frames, the first wave packet corresponds to the first skip and the second wave packet is for the second skip. There is very little difference between umbra, penumbra, and quiet Sun for the first skip, which is expected because of the large depth below the spot for the first-skip rays. There are sizeable differences between the quiet Sun times and the spot times for the second skip, which might be expected. Differences are seen in both envelope and phase travel times and the covariance amplitudes.

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