Thermodynamics of Mixed Stratocumulus Layers: Saturation Point Budgets

Abstract

Saturation point (SP) diagrams and a circulation model are used to analyze the thermodynamics of mixed stratocumulus layers, and develop conceptual tools for observational and parametric analyses. These models show the relation between SP structure and the thermodynamic fluxes for steady and unsteady mixed layers, couple convective and radiative fluxes at cloud top and within the layer, and suggest closure conditions on the circulation energetics using θ_v, isopleths. The steady-state model shows a mixing line SP structure below cloud top with correspondingly simple surface flux parameterizations. The time-dependent mixed layer budgets are formulated using an SP vector diagram to show the approach to equilibrium, the internal circulation, and the relationship between Eulerian and Lagrangian flux descriptions.