Observations of Convectively Generated Gravity Waves within the Stratiform Region of Mesoscale Convective Systems

The diabatic heating and cooling associated with convection is known to generate low-frequency gravity waves that propagate horizontally and influence the surrounding environment and convection. Mesoscale convective systems (MCSs) generate a few types of gravity waves. The convective region, which is characterized by heating throughout the depth of the troposphere, produces waves that have upward or downward motion through the depth of the troposphere and propagate relatively quickly away. The stratiform region, which its upper-level heating and low-level cooling, produces a vertical dipole of upward and downward motion that propagates outward more slowly. Numerical simulations and observations have shown that gravity waves that propagate ahead of the storm can modify the preceding environment so that it is more conducive for convective initiation and development. However, relatively little work has been done to investigate how these waves impact the development and evolution of the stratiform region, especially from an observational perspective.

As a first step to understanding the impact of these waves on the stratiform region, we will demonstrate that gravity waves can be identified in the trailing stratiform region of a squall line. A series of potential waves features are identified using data from the Mid-Latitude Continental Convective Clouds Experiment (MC3E) and the Oklahoma Mesonet. We will also look at how these waves relate to the environment, including their association with the cold pool, and potential impacts on the microphysical characteristics of the surrounding stratiform region.