Chromospheric Heating by Acoustic Waves Compared to Radiative Cooling. II. Revised Grid of Models

Abstract

Abstract Acoustic and magnetoacoustic waves are considered to be possible agents of chromospheric heating. We present a comparison of deposited acoustic energy flux with total integrated radiative losses in the middle chromosphere of the quiet Sun and a weak plage. The comparison is based on a consistent set of high-resolution observations acquired by the Interferometric Bidimensional Spectrometer instrument in the Ca ii 854.2 nm line. The deposited acoustic-flux energy is derived from Doppler velocities observed in the line core and a set of 1737 non-local thermodynamic equilibrium 1D hydrostatic semi-empirical models, which also provide the radiative losses. The models are obtained by scaling the temperature and column mass of five initial models by Vernazza et al. (1981; VAL) B–F to get the best fit of synthetic to observed profiles. We find that the deposited acoustic-flux energy in the quiet-Sun chromosphere balances 30%–50% of the energy released by radiation. In the plage, it contributes by 50%–60% in locations with vertical magnetic field and 70%–90% in regions where the magnetic field is inclined more than 50°  to the solar surface normal.