Although most tsunamis are generated by the sea-bottom deformation
caused by earthquakes, some tsunamis are excited by sea-surface pressure
changes. This study theoretically investigated tsunamis generated by
sea-surface pressure changes and derived the solutions in 3-D space,
whereas most past studies employed 2-D equations. Using the solutions,
we simulated and visualized the tsunami generation by a growing pressure
change. Negative pressure change made the sea surface uplifted inside
the source region and negative leading waves were radiated from the
source region. We also simulated the tsunami generation when the
pressure change at the sea surface moves with almost the same speed as
the tsunami propagation velocity. The tsunami height increased with
increasing the travel distance including the dispersion effects. The 3-D
solutions in this study, including the vertical velocity distribution,
indicate that both the tsunami height and the sea-surface pressure
changes contribute to the ocean-bottom pressure changes, suggesting the
difficulty in measuring the tsunami height with ocean-bottom pressure
observations. When the pressure change source was characterized by
short-wavelength components, the dispersion increased tsunami height
more extensively than the non-dispersive tsunamis. The 3-D solutions are
necessary for describing the tsunami generation where the long-wave
approximations are not applicable in open oceans.