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Statistical properties of Hα jets in the polar coronal hole and their implications in coronal activities

Dynamic features, such as chromospheric jets, transition region network jets, coronal plumes and coronal jets, are abundant in the network regions of the solar polar coronal holes. We investigate the relationship between chromospheric jets and coronal activities (e.g., coronal plumes and jets).We analyze observations of a polar coronal hole including the filtergrams that were taken by the New Vacuum Solar Telescope (NVST) at the Hα-0.6 Åto study the Hα jets,and the Atmospheric Imaging Assembly (AIA) 171 Å images to follow the evolution of coronal activities. Hα jets are persistent in the network regions, only some regions (denoted as R1-R5) are rooted with discernible coronal plumes.With an automated method, we identify and track 1 320 Hα jets in the network regions. We find that the average lifetime, height and ascending speed of the Hα jets are 75.38 s, 2.67 Mm, 65.60 km s$^{-1}$, respectively. The Hα jets rooted in R1-R5 are higher and faster than those in the others. We also find that propagating disturbances (PDs) in coronal plumes have a close connection with the Hα jets. The speeds of 28 out of 29 Hα jets associated with PDs are about 50 km s$^{-1}$ . In a case of coronal jet, we find that the speeds of both the coronal jet and the Hα jet are over 150 km s$^{-1}$, suggesting that both cool and hot jets can be coupled together. Based on our analyses, it is evident that more dynamic Hα jets could release the energies to the corona, which might be the results of the development of Kelvin-Helmholtz instability (KHi) or small-scaled magnetic activities. We suggest that chromospheric jets, transition region network jets and ray-like features in the corona are coherent phenomena, and they are important tunnels for cycling energy and mass in the solar atmosphere.