The Advantage of a Lagrangian Analysis for Understanding the Convective System Core – Anvil Area Relationship

Stratiform anvil areas strongly impact radiation. Therefore, accurately parameterizing their sizes in climate models is important for constraining hydrology and cloud feedbacks. While some cloud features are related to the co-located instantaneous environment or other instantaneous cloud properties (e.g., cloud optical depth related to current condensate properties and cloud coverage), anvil area extent is not instantaneously related to the convective cores at the same time snapshot. Instead, areal extent reflect the histories of the cores embedded in the system, which incrementally detrain as the system progresses. This motivates a perspective that the time tendency itself (of area extent) is a function of current core properties, with actual areal extent at the same time being the integration of all areal extent time tendencies over the previous lifecycle stages of the system. Analyses along this line require convective system tracking, which we employ to develop an analytical time tendency model for anvil areal extent connected to convective core latent heating structure. We find that the analytical model is skillful enough to explain large eddy simulation (LES) anvil area behavior, anvil area tendencies in different states of convective organization, and tracked tropical mesoscale convective systems (MCSs) anvil area tendencies in general. The overarching goal is to arrive at a simple model jointly informed by combining satellite, ground based observations, and MCS simulations that is useful for understanding stratiform anvil area changes in different (and potentially trending) environments.