Chromospheric Upflow Events Associated with Transition Region Explosive Events

Transition region explosive events are considered to be a manifestation of small scale magnetic reconnection ubiquitously occurring --- even in the quiet Sun. In this paper, we report a close association between transition region explosive events and chromospheric upflow events seen in Hff. From a comparison of the Big Bear Solar Observatory (BBSO) Hff spectrograph data and the Solar and Heliospheric Observatory (SOHO) / Solar Ultraviolet Measurements of Emitted Radiation (SUMER) data, we found a succession of chromospheric upflow events at sites where repeated explosive events occurred. Individual chromospheric events appear as compact dark features which are best visible in Hff-0.5 A, and have a size of 2-3 arc seconds and a lifetime of 1-2 minutes. They are characterized by an upward motion of 15-30 km s \Γ1 , a temperature of 10 4 K, a mass density of 1 \Θ 10 \Γ13 g, and a non-thermal velocity less than 10 km s \Γ1 . Unlike spicules, which display descendin...