Is GCM-Simulated Tropical Anvil Peak Constrained by Basic Physics?
Tropical anvil clouds play a crucial role in Earth's radiation balance, yet uncertainties persist regarding the processes governing their fractional coverage and changes under warming, and the fidelity of GCMs in simulating them. Understanding to what extent GCMs can accurately simulate the tropical anvil peak is therefore imperative. To address this, we conducted a series of nudged simulations using GFDL's latest atmosphere climate model, employing a hierarchy of cloud fraction parameterization schemes: prognostic (most complex), PDF-based diagnostic (intermediately complex), and binary (simplest) schemes. Through these hierarchical simulations and mechanism-denial experiments, we reveal that the simulated peak in anvil cloudiness in GCMs is primarily constrained by fundamental physical laws of thermodynamics and dynamics, with minimal influence from model tuning. The implications of these findings for understanding anvil cloud feedback are discussed.