  We calculate the Nernst signal directly in the phenomenological
two-dimensional XY model. The obtained numerical results are consistent with
the experimental observations in some high-Tc cuprate superconductors
qualitatively, where the vortex Nernst signal has a characteristic tilt-hill
profile. It is suggested that the excitations of vortex and anti-vortex in 2D
is the possible origin of the anomalous Nernst effect.
