Damping and power spectra of quasi-periodic intensity disturbances above a solar polar coronal hole

TL;DR

This study analyzes the damping and power spectra of intensity disturbances in a solar polar coronal hole, revealing their frequency-dependent damping behavior and potential origins from spicule-triggered slow magnetoacoustic waves.

Contribution

It provides new insights into the physical nature of intensity disturbances, highlighting their damping characteristics and possible wave-spicule interactions in the solar polar coronal hole.

Findings

Damping is stronger at lower frequencies.

No significant difference between 171 Å and 193 Å passbands.

Power spectra suggest a mixture of spicule and wave activities.

Abstract

We study intensity disturbances above a solar polar coronal hole seen in the AIA 171 \AA\ and 193 \AA\ passbands, aiming to provide more insights into their physical nature. The damping and power spectra of the intensity disturbances with frequencies from 0.07 mHz to 10.5 mHz are investigated. The damping of the intensity disturbances tends to be stronger at lower frequencies, and their damping behavior below 980" (for comparison, the limb is at 945") is different from what happens above. No significant difference is found between the damping of the intensity disturbances in the AIA 171 \AA\ and that in the AIA 193 \AA. The indices of the power spectra of the intensity disturbances are found to be slightly smaller in the AIA 171 \AA\ than in the AIA 193 \AA, but the difference is within one sigma deviation. An additional enhanced component is present in the power spectra in a period range of 8--40 minutes at lower heights. While the power spectra of spicule is highly correlated with its associated intensity disturbance, it suggests that the power spectra of the intensity disturbances might be a mixture of spicules and wave activities. We suggest that each intensity disturbance in the polar coronal hole is possibly a series of independent slow magnetoacoustic waves triggered by spicular activities.