The Stratospheric Gravity Wave Field and Momentum Fluxes Produced by Isolated Supercells

Alongside topographic forcing, deep moist convection makes a significant contribution to the global budget of upward momentum transport by gravity waves. Long-lived thunderstorms with rotating updrafts, known as supercells, produce strong and highly variable vertical motions over several hours. This study uses an idealized modeling framework in WRF to simulate supercells and their associated gravity waves up to 60 km altitude for multiple different wind profiles and convective modes. In contrast to many previous studies, the supercell is brought to an end and the simulations continue until most of the wave energy has dissipated. Thus, upward momentum transport can be computed over the entire life cycle of the storm and its associated waves, providing a more complete picture of the total impact of the event. The shapes of the wind profiles in the upper troposphere and lower stratosphere are found to strongly control the total momentum and energy transported into the upper stratosphere, so varying the stratospheric wind profile illuminates the behavior of the gravity waves in the stratosphere, particularly their vertical propagation. We also investigate the extent to which different modes of supercell structure, such as high-precipitation, low-precipitation, and classic supercells, lead to different intensities and spectra of the resulting gravity waves. In addition, the WRF model diabatic heating and vertical motions will be used as forcing conditions for stratospheric models such as MAGIC and CGCAM for the purposes of 1) comparison to WRF results between 20 and 60 km, and 2) so that wave propagation, momentum transport, wave breaking, and momentum deposition can be evaluated to altitudes above 80 km.