Sensitivities of Tropical Pacific Precipitation Simulations to Physical Parameters in CAM6 and Implications for AGCMs

Abstract In this study, we examined the key parameters within deep convection scheme and cloud physics scheme of the CAM6 model to ascertain their significance and influence on simulating mean precipitation in the tropical Pacific. Through simultaneously perturbing 12 selected parameters from deep convection and cloud physics schemes, we conducted perturbed parameter ensemble (PPE) experiments with 128 members. Our analysis uncovered that the parameters showing the most influential effects on tropical Pacific precipitation simulations can be separated into two distinct categories: those primarily governed by the convection scheme, which reflects the competition between convective and large‐scale precipitation, and those predominantly influenced by cloud ice processes. Furthermore, we revealed the importance of nonlinear effects of these perturbed parameters on the simulation of mean precipitation and interpreted the underlying mechanisms. Some biases in simulating precipitation revealed by our PPE experiments align with those in AMIP simulations, offering valuable insights for the AGCM's advancement.