Issn 1845–8319 an Estimate of Chromospheric Heating by Acoustic Waves

Several mechanisms may heat the solar chromosphere: acoustic waves, magnetoacoustic waves (slow, fast, and Alfvén waves), and small-scale magnetic reconnections. Based on observations in the Ca II 854.2 nm line, the contribution of acoustic waves to the heating of quiet and plage regions in the chromosphere is discussed. The energy released by radiative losses is compared with the energy deposited by acoustic waves. Radiative losses are computed using a grid of six semi-empirical models VAL A–F. The deposited acoustic flux is calculated using power spectra of Doppler oscillations measured in the Ca II line core. The comparison shows that the spatial correlation of maps of radiative losses and acoustic flux is 70 %. The deposited acoustic flux provides at least 25–30 % of the energy radiated in the quiet chromosphere and 50 % in plage regions.