Magnetic Reconnection Rates and Energy Release in a Confined X-class Flare

We study the energy-release process in the confined X1.6 flare that occurred on 22 October 2014 in AR 12192. Magnetic-reconnection rates and reconnection fluxes are derived from three different data sets: space-based data from the Atmospheric Imaging Assembly (AIA) 1600 A filter onboard the Solar Dynamics Observatory (SDO) and ground-based H\(\upalpha \) and Ca ii K filtergrams from Kanzelhohe Observatory. The magnetic-reconnection rates determined from the three data sets all closely resemble the temporal profile of the hard X-rays measured by the Ramaty High Energy Solar Spectroscopic Imager (RHESSI), which are a proxy for the flare energy released into high-energy electrons. The total magnetic-reconnection flux derived lies between \(4.1 \times 10^{21}~\mbox{Mx}\) (AIA 1600 A) and \(7.9 \times10^{21}~\mbox{Mx}\) (H\(\upalpha \)), which corresponds to about 2 to 4 % of the total unsigned flux of the strong source AR. Comparison of the magnetic-reconnection flux dependence on the GOES class for 27 eruptive events collected from previous studies (covering B to \({>}\,\mathrm{X10}\) class flares) reveals a correlation coefficient of \({\approx}\,0.8\) in double-logarithmic space. The confined X1.6 class flare under study lies well within the distribution of the eruptive flares. The event shows a large initial separation of the flare ribbons and no separation motion during the flare. In addition, we note enhanced emission at flare-ribbon structures and hot loops connecting these structures before the event starts. These observations are consistent with the emerging-flux model, where newly emerging small flux tubes reconnect with pre-existing large coronal loops.