Intensity and doppler velocity oscillations in pore atmospheres

We have investigated chromospheric traveling features running across two merged pores from their centers at speeds of about 55 km s^-1, in the active region AR 11828. The pores were observed on 2013 August 24 by using high-time, spatial, and spectral resolution data from the Fast Imaging Solar Spectrograph of the 1.6 m New Solar Telescope. We infer a line-of-sight (LOS) velocity by applying the lambdameter method to the Ca ii 8542 band and Hα band, and investigate intensity and LOS velocity changes at different wavelengths and different positions at the pores. We find that they have three-minute oscillations, and the intensity oscillation from the line center (0.0 ) is preceded by that from the core (-0.3 ) of the bands. There is no phase difference between the intensity and the LOS velocity oscillations at a given wavelength. The amplitude of LOS velocity from the near core spectra () is greater than that from the far core spectra (). These results support the interpretation of the observed wave as a slow magnetoacoustic wave propagating along the magnetic field lines in the pores. The apparent horizontal motion and a sudden decrease of its speed beyond the pores can be explained by the projection effect caused by inclination of the magnetic field with a canopy structure. We conclude that the observed wave properties of the pores are quite similar to those from the sunspot observations.