Analyzing the Indian Summer Monsoon through Perturbed Parameter Ensembles

Indian summer monsoon rainfall is important to the livelihood of a substantial portion of the world’s population. However, monsoon predictions are limited in accuracy since their rainfall characteristics are dependent on small-scale physics processes that are not fully understood and represented in climate models. To begin understanding how monsoon rainfall depends on physics processes in climate models, we analyzed a perturbed parameter ensemble (PPE) of the CESM2-CAM6 model, where each PPE member is characterized by different physics parameter settings which in turn impacts the climate and rainfall of each member. Using the rainfall data from all PPE members, we develop a multiple linear regression model to assess whether there are any significant relationships between the physics parameters choices and the intensity of the monsoon rainfall cycle. We hope that our findings will contribute to an increased understanding and representation of the Indian monsoon in climate models, given the importance climate model predictions play in informing society of the expected changes in rainfall patterns as the climate warms.