Decomposition of Monsoon Dynamics: Reconciling Data and Model Comparison for Geological Time Periods

Understanding past climate informs our future scenarios. Proxy data and climate models are vital for studying past climate change, but discrepancies often arise between these approaches. This study introduces an innovative approach that reconciles proxy data with models by decomposing the physical processes driving monsoon precipitation changes. Focusing on East Asian Summer Monsoon (EASM) precipitation across significant periods in the PMIP, our analysis highlights: 1) the dominance of dynamic effects over thermodynamic effects during the mid-Holocene, 2) contrasting impacts of thermodynamic and dynamical processes during the Last Glacial Maximum, and 3) distinct regional controls of thermodynamic and dynamical processes in the mid-Piacenzian warm period, reflecting diverse water vapor sources. The study concludes that decomposing the physical processes of precipitation aids in reconciling records and simulations. It asserts that simulations consistently yield a decomposed process that spatially aligns with the records. The mismatch between records and simulations primarily arises from simulation biases in the relative contributions of the decomposed physical processes to precipitation changes, suggesting a need for improvement in simulations.