Authors: Mehmet Sarp Yalim (The University of Alabama in Huntsville), Clayton Reece (University of Georgia), Christian Beck (National Solar Observatory), Sanjiv K. Tiwari (SETI Institute), Debi Prasad Choudhary (California State University Northridge), Sushree Nayak (University of Balear Islands), Sanjay Gosain (National Solar Observatory)

Understanding the mechanisms underlying the heating of the solar atmosphere is a fundamental problem in solar physics. Various mechanisms have been proposed to account for the thermal structure and heating of the solar atmosphere that contributes to the remarkable temperature increase from ∼5000 K on the photosphere to ∼1 million K in the corona. The lower atmosphere of the Sun (i.e., photosphere and chromosphere) is composed of weakly ionized plasma where ions, electrons, and neutrals coexist. This results in anisotropic dissipation of electric currents by Coulomb and Cowling resistivities. In this work, we investigate the time-dependent variation of a Joule heating event of a sunspot umbral light bridge due to dissipation of electric currents that are perpendicular to the magnetic field by Cowling resistivity (i.e., Cowling heating). We have already demonstrated that Cowling heating is a prominent heating mechanism for the sunspot umbral light bridge located in NOAA AR 12121 on 2014 July 27. Here, we focus on the same target region to analyze the variation of Cowling heating within a ∼3-hour period by using space-borne and ground-based instrument data, namely NASA’s IRIS slit-spectrograph, SDO/HMI magnetogram, and NSO’s Dunn Solar Telescope (DST) IBIS spectropolarimeter data. We found correlation between Cowling heating rate vs. temperature supporting our previous findings as well as compared our results that we obtained using the inverted temperature data from the DST/IBIS and IRIS spectral data.