A Global Satellite and MERRA-2 Perspective of the Role of Planetary Boundary Layer Thermodynamics on the Lifetime of Deep Convective Systems

General Circulation Models (GCMs) still have difficulty simulating the partitioning between convective and stratiform rainfall, and simulating the onset and demise of deep convection. In nature, such characteristics are tied to the lifecycle stages and distribution of convective system lifetimes. But what governs the distribution of convective system lifetimes? Addressing this question requires a comprehensive sampling of the environments in close proximity to convective systems of varying durations (and as a function of their lifecycle stages). Along this line, I discuss our efforts to use multiple satellite products and MERRA-2 to quantify the large-scale and local thermodynamic state close to propagating convective systems, and discuss the impact of mesoscale fluctuations in the planetary boundary layer on convective system growth, decay and ultimately, lifetime. The extent to which boundary layer perturbations are associated with SST variations (i.e. an external, large-scale control) versus convective feedback (through downdrafts/cold pools) is discussed within the context of determining if large-scale environments or small-scale features are largely responsible for the observed distribution of convective system lifetimes. The degree to which MERRA-2 plausibly captures the coupled relationship between deep convection and boundary layer thermodynamics is also assessed. Such knowledge has implications for current GCM convection and cloud parameterization efforts.