ERRATUM: “Determination of the chromospheric quiet network element area index and its variation between 2008 and 2011” (RAA, Vol. 12, p.201 [2012])

As a result of the authors＇ error, the paper ＂Determination of the chromospheric quiet network element area index and its variation between 2008 and 2011＂ by Singh, J. et al. （RAA, Vol. 12, p.201 [2012]） contains errors in page 206. In the original article, the top right and bottom images were inadvertently interchanged in Figure 5. The correct sequence of images is shown in this erratum. Figure caption and details about the images remain unchanged.

Determination of the chromospheric quiet network element area index and its variation between 2008 and 2011

In general, it is believed that plages and sunspots are the main contribu- tors to solar irradiance. There are small-scale structures on the Sun with intermediate magnetic fields that could also contribute to solar irradiance, but it has not yet been quantified how many of these small scale structures contribute and how much this varies over the solar cycle. We used Ca II K images obtained from the telescope at the Kodaikanal observatory. We report a method to separate the network elements from the background structure and plage regions, and compute the changes in the network element area index during the minimum phase of the solar cycle and part of the as- cending phase of cycle 24. The measured area occupied by the network elements is about 30% and the plages cover less than 1% of the solar disk during the observation period from February 2008 to 2011. During the extended period of minimum activity, it is observed that the network element area index decreases by about 7% compared to the area occupied by the network elements in 2008. A long term study of the network element area index is required to understand the variations over the solar cycle.

Statistical analysis of dynamic fibrils observed from NST/BBSO observations

We present the results obtained from the analysis of dynamic fibrils in NOAA active region （AR） 12132, using high resolution Ha observations from the New Solar Telescope operating at Big Bear Solar Observatory. The dynamic fibrils are seen to be moving up and down, and most of these dynamic fibrils are periodic and have a jet-like appearance. We found from our observations that the fibrils follow almost perfect parabolic paths in many cases. A statistical analysis on the properties of the parabolic paths showing an analysis on deceleration, maximum velocity, duration and kinetic energy of these fibrils is presented here. We found the average maximum velocity to be around 15 km s-1 and mean deceleration to be around 100 m s-2. The observed deceleration appears to be a fraction of gravity of the Sun and is not compatible with the path of ballistic motion due to gravity of the Sun. We found a positive correlation between deceleration and maximum velocity. This correlation is consistent with simulations done earlier on magnetoacoustic shock waves propagating upward.