  We calculate the angular momentum and energy of a vortex dipole in a trapped
atomic Bose-Einstein condensate. Fully analytic expressions are obtained. We
apply the results to understand a novel phenomenon in the MIT group experiment,
an excellent agreement is achieved, and further experimental investigation is
proposed to confirm this vortex dipole mechanism. We then suggest an effective
generation and detection of vortex dipole for experimental realization.
Application of the sum rule to calculate collective mode frequency splitting is
also discussed.
