We present the occurrence of waves patterns on the southern polar region of Mars as traced by the O-2 dayglow emission at lambda = 1.27 mu m during late winter/early spring of MY 28. The observations were carried out by the OMEGA (Observatoire pour la Mineralogie, l'Eau, les Glaces et l'Activite) imaging spectrometer on board Mars Express (MEX). Waves are found preferentially at high incidence angles and latitudes between 55 degrees and 75 degrees S. The dayglow intensity fluctuations are of the order of +/- 3% at incidence angle <88.5 degrees and they can be explained by the propagation of gravity waves in the Martian atmosphere. Mesoscale meteorological modeling predicts gravity wave activity in the same range of latitude as the observed O-2(a(1)Delta(g)) wave patterns with temperature oscillations consistent with existing measurements. Moreover, gravity waves simulated through mesoscale modeling can induce dayglow fluctuations of the same order-of-magnitude as observed in the OMEGA maps. This study confirms that airglow imagery is a powerful method to detect and study the bi-dimensional propagation of gravity waves, as foreseen in previous studies coupling photochemical and dynamical models.