Breakdown of Vertically Propagating Two-Dimensional Gravity Waves Forced by Orography

摘要: Abstract The propagation of orographic gravity waves into an atmosphere with exponentially decreasing density is simulated a two-dimensional, nonlinear, time-dependent numerical model. After the stationary wave established over mountain, model predicts that breaking causes large reduction vertical momentum flux in flow, not only at levels where present, but also far below lowest occurrence overturning. More than half decrease explained by presence amplitude, downward propagating waves, which are generated regions breaking. appear almost simultaneously overturning, and have nonzero phase speeds, suggesting strongly nonlinear generation mechanism depends on local properties. these robust process, insensitive to mountain height, width, or scale height. These results important implica...