Title: Evidence for coherent spicule oscillations by correcting Hinode/SOT Ca II H in the southeast limb of the Sun,
Abstract: Wave theories of heating the chromosphere, corona, and solar wind due to
photospheric fluctuations are strengthened by the existence of observed wave
coherency up to the transition region (TR). The coherency of solar spicules'
intensity oscillations was explored using the Solar Optical Telescope (SOT) on
the Hinode spacecraft with a height increase above the solar limb in active
region (AR). We used time sequences near the southeast region from the
Hinode/SOT in Ca II H line obtained on April 3, 2015 and applied the
de-convolution procedure to the spicule in order to illustrate how effectively
our restoration method works on fine structures such as spicules. Moreover, the
intensity oscillations at different heights above the solar limb were analysed
through wavelet transforms. Afterwards, the phase difference was measured among
oscillations at two certain heights in search of evidence for coherent
oscillations. The results of wavelet transformations revealed dominant period
peaks in 2, 4, 5.5, and 6.5 min at four separate heights. The dominant
frequencies for coherency level higher than 75 percent was found to be around
5.5 and 8.5 mHz. Mean phase speeds of 155-360 km s-1 were measured. We found
that the mean phase speeds increased with height. The results suggest that the
energy flux carried by coherent waves into the corona and heliosphere may be
several times larger than previous estimates that were based solely on constant
velocities. We provide compelling evidence for the existence of upwardly
propagating coherent waves.