Wave heating of the lower solar atmosphere

We present direct observations of temperature fluctuations in the solar chromosphere in an active region, obtained with Band 6 of the Atacama Large Millimeter/submillimeter Array (ALMA), in four sub- bands at 1.21, 1.22, 1.29, and 1.3 mm. These were complemented by co-observations of the same target with the Interface Region Imaging Spectrograph (IRIS) space telescope, and with the Solar Dynamic Observatory (SDO), in a wide range of far and near-ultraviolet spectral windows. Furthermore, co-observations of the same target with the Hinode/SOT have provided us with extensive information about the photospheric physical parameters, such as magnetic field, temperature and line-of-sight velocity. These were calculated using the SPINOR (height-dependent) spatially coupled inversion of the Hinode/SP spectro-polarimetric data. By employing wavelet analysis, we present relationships between propagation of magneto-acoustic waves through the lower solar atmosphere and the temperature fluctuations observed with ALMA. In addition, we compare the temperature fluctuations with transverse and line-of-sight velocity oscillations in chromospheric fibrillar structures observed at various heights. Lastly, we provide a detailed comparison of temperature stratification in the lower solar atmosphere from Hinode-ALMA-IRIS and from numerical models. These provide us with new insights into the nature of various wave phenomena in the solar chromosphere, thus, their role in heating the upper solar atmosphere.