  We report on a numerical study of the critical velocity for creation of
quantized vortices by a moving Gaussian obstacle in a trapped Bose-Einstein
condensate, modeled by the Gross-Pitaevskii equation. We pay attention to
impact of density inhomogeneity associated with the global inverted-parabolic
profile by a trapping potential as well as the local density suppression around
the Gaussian obstacle. When the width of the Gaussian potential is large, the
wake dynamics is significantly influenced by the nonuniformity around the
obstacle potential. The critical velocity, estimated through the time interval
between the first and second vortex emission, can be explained by the local
sound velocity by taking into account the above two contributions. We also find
that the ratio of the critical velocity to the sound velocity at the center of
the system is insensitive to the nonlinear coefficient of the Gross-Pitaevskii
equation, which supports the universal discussion even in a inhomogeneous
trapped condensate under the local density approximation.
