Atmospheres of evolved AGB stars are heavily affected by pulsation, dust
formation and mass loss, and they can become very extended. Time series of
observed high-resolution spectra proved to be a useful tool to study
atmospheric dynamics throughout the outer layers of these pulsating red giants.
Originating at various depths, different molecular spectral lines observed in
the near-infrared can be used to probe gas velocities there for different
phases during the lightcycle. Dynamic model atmospheres are needed to represent
the complicated structures of Mira variables properly. An important aspect
which should be reproduced by the models is the variation of line profiles due
to the influence of gas velocities. Based on a dynamic model, synthetic spectra
(containing CO and CN lines) were calculated, using an LTE radiative transfer
code that includes velocity effects. It is shown that profiles of lines that
sample different depths qualitatively reproduce the behaviour expected from
observations.Comment: accepted by A&A, 12 pages, 9 figure