ABSTRACT |
A 2D dry incompressible vorticity-stream function model is
developed and used to investigate nonlinear buoyancy waves, especially
internal solitary waves and related phenomena in the lower atmosphere.
Using this model some essential properties of internal solitary waves
have been successfully simulated. For the first time in the simulation
reversed recirculation within large amplitude solitary waves has been
found. The existence of recirculation enables large amplitude solitary
waves to trap air and transport it. Meanwhile, due to viscosity the
trapped air continuously leaks out during the transport. The influences
of surface friction and ambient vertical wind shear on solitary waves
are also studied.
On the basis of the preceding studies, an internal solitary wave generated by a thunderstorm outflow, observed by NSSL's Doppler radar, a 444m tall tower and a surface network, is modeled. The simulation results show a quite good agreement with the observation in several aspects. The simulation also gives us a further understanding of the origin, propagation, and decay of the solitary wave, as well as its detailed kinematic and themodynamic structure. |