Low-Frequency Gravity Wave Generation during Mesoscale Convective System Lifecycles within Varying Environments

Mesoscale Convective Systems (MCSs) frequently generate low-frequency gravity waves that propagate away from the system and modify the surrounding environment. Common events that are part of an MCS lifecycle are found to correspond to low-frequency wave generation. Initial convective development, associated with the first internal mode of heating, produces a wave with subsidence through the depth of the troposphere and a decrease in environmental convective instability. Subsequent generating events include the initial development of precipitation, the first appearance of stratiform precipitation, and substantial increases in rear inflow. Each of these events are associated with increases in low- and mid-level cooling, and thus generate low-frequency gravity waves associated with lifting and destabilization of the atmosphere. Events with cooling, and hence, lifting concentrated in the lower levels have a larger impact on the surrounding environmental stability field than if it is concentrated in the mid-levels. Ambient environmental factors such as instability and shear are found to control the location and depth of the latent cooling, and hence also controlled the magnitude of the impact of the generated gravity wave on the surrounding environment. Additional work examines how modification of microphysical characteristics within the MCS affects the vertical latent cooling profile and associated gravity wave generation.