Lagrangian and Eulerian stratifications of acoustic oscillations through the solar photosphere

We evaluate the stratification of acoustic oscillations in the solar photos phere in both the Lagrangian (comoving) frame of reference and the Eulerian (inertial) frame of reference, from a temporal sequence of model atmospher es in an optical depth scale obtained after a quasi-non-LTE inversion of th e radiative transfer equation applied to spectral observations of the K I 7 699 Angstrom line. Our results suggest that, to first order, the photospher e moves up and down as a whole with amplitudes ranging from similar to8 km in deep layers (around 0 km) to similar to 19 km in the upper layers (aroun d 640 km). In Lagrangian coordinates, we observe numerous short-lived, loca l temperature and velocity amplitude enhancements in medium-high layers, to gether with asymmetric waveforms in the oscillation of these two physical q uantities. The Lagrangian temperature oscillation clearly shows two nodes a ssociated with sharp phase jumps of about 180 degrees, whereas the velocity amplitude shows the well-known increase with geometrical height, at nearly constant phase. In Eulerian coordinates, the perturbations are dominated b y the coherent oscillation of the entire photosphere.