¥Gravity waves are
simulated at the jet exit regions associated with dipoles. In
the surface dipole case, gravity waves are generated near the surface and
do not propagate above 5km at later time. In the mid-level dipole case,
gravity waves are generated near the jet exit region and propagate both
upward and downward. Gravity waves generated from a tropopause level
dipole propagate upward mostly.
¥Four dimensional ray
tracing model accommodates the temporal and spatial
variations of the background wind from the dipole simulation.
Our results show that as the gravity waves propagate
upward, wave characteristics changes significantly.
¥Horizontal and vertical wave wavelength
decreases.
¥Intrinsic group velocity decreases but never
vanishes. Wave packets are finally almost advected by weak mean wind.
¥Intrinsic frequency are close to inertial
frequency.
¥How gravity waves are
generated has not been fully understood. Spontaneous wave
emission could be most possibly generation mechanism
for gravity waves in vortex pairs.