Thursday, 20 June 2002
Interaction of trapped lee waves and the convective boundary layer
Trapped lee waves have been observed to exhibit a transient nature. Three
possibilities have been suggested to explain the transience: changes in the
ambient upstream conditions, an evolving lee-side atmospheric boundary layer,
or wave-wave interactions. Herein, we explore the
interaction between trapped lee waves and an evolving convective
boundary layer (CBL) using simulations with idealized topography.
The first simulation is initialized with a wind and stability profile
assuring trapped waves. In this simulation, no surface heating is emloyed.
A second simulation is initialized with the same stability profile, but no
wind. Surface heating is included via the model's radiation
parameterization. A third simulation allows development of trapped lee
waves and CBL simultaneously. Difference fields are calculated to quantify
the influence of the trapped lee-wave system on the CBL and vice versa.
In addition, vertical profiles of tendencies from model heat, moisture,
and momentum equations are written out at each timestep for several points
throughout the model's horizontal domain for each simulation. Regions of
particular interest include the downslope flow along the lee slope, lee-wave
updrafts and downdrafts, and the rotor located beneath lee-wave crests.
Time series of the model tendencies are analyzed to describe and quantify
the underlying dynamics associated with the lee-wave/CBL interaction.
Supplementary URL: