Numerical Simulations of Vertically Propagating Gravity Waves in the Stratosphere above a Hydrostatic Large Amplitude Surface Gravity Wave on December 12th, 2002

A large amplitude gravity forms over eastern, Texas on December 12, 2002. Numerical simulations were done with the Non-Hydrostatic Mesoscale Atmospheric Simulation System (NHMASS) model to study the geostrophic adjustments and environment favorable for gravity wave formation. In response to the large amplitude gravity wave a squall line forms in both the real atmosphere and model. The moist convection in turn redistributes the atmosphere favorably for vertically propagating gravity waves into the stratosphere. Multiple nested model runs are done with the NHMASS to study the environment favorable for vertically propagating gravity waves. Results are found similar to Uccellini and Koch (1987) for the environment of the large amplitude gravity across eastern Texas and Louisiana. Various turbulence parameters are then used to study the environment favorable for vertically propagating gravity waves. Low Richardson numbers and high variation of the score parameter with height above the upper level jet/front system provide an adequate environment for vertically propagating gravity waves well into the stratosphere. The moist convection helps to induce and organize an upstream propagating wave into the lower stratosphere, which breaks and further perturbs the lower stratosphere.