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The heating of the Sun's chromosphere remains poorly understood. Whileprogress has been made on understanding what drives the quiet Sun internetworkchromosphere, chromospheric heating in strong magnetic field regions continuesto present a difficult challenge, mostly because of a lack of observationalconstraints. We use high-resolution spectropolarimetric data from the Swedish1-m Solar Telescope to identify the location and spatio-temporal properties ofheating in the magnetic chromosphere. In particular, we report the existence ofraised-core spectral line profiles in the Ca II 8542 line. These profiles arecharacterized by the absence of an absorption line core, showing a quasi-flatprofile between +/- 0.5 {\AA}, and are abundant close to magnetic bright-pointsand plage. Comparison with 3D MHD simulations indicates that such profilesoccur when the line-of-sight goes through an "elevated temperature canopy"associated with the expansion with height of the magnetic field of fluxconcentrations. This temperature canopy in the simulations is caused by ohmicdissipation where there are strong magnetic field gradients. The raised-coreprofiles are thus indicators of locations of increased chromospheric heating.We characterize the location and temporal and spatial properties of suchprofiles in our observations, thus providing much stricter constraints ontheoretical models of chromospheric heating mechanisms than before.

Heating of the magnetic chromosphere: observational constraints from Ca II 8542 spectra