The NASA Ames general circulation model has been used to compute time series for atmospheric products of inertia and relative angular momentum terms. Model outputs were used also to compute time series representing the inertia terms due to CO2 condensation and sublimation on the surface of Mars. Some of these terms were used to generate time series representing the forcing functions for the equatorial components of the linearized Liouville equations of rotational motion. These equations were then solved numerically for a period of a Martian year (669 sols) to obtain a time series for the position of the rotation pole on the surface of Mars. The results of the investigation indicate that mass variation in the atmosphere is as important as the formation and sublimation of ice caps on the surface of the planet. Numerical integration of the equations of rotational motion yields pole displacements as large as 30.9 cm (ice caps solution), 39.5 cm (atmospheric effects), or 33 cm (both effects combined). Fourier analysis of the time series corresponding to the equatorial components of pole displacement for the ice caps solution as well as the atmospheric effects solution shows that the (1/3)-annual harmonic has the largest coefficient in three cases, with magnitudes in the 7--9 cm range. Fourier analysis of the equatorial components of polar motion for the combined solution yields main harmonics of 5.12 cm (x), (1/3)-annual and 7.50 cm (y), annual.