Evaluation of Intra-seasonal Variability of the Asian Monsoon in GFDL's Latest Climate Model

Verifying model representations of observed atmospheric phenomena is necessary to hone a model’s predictive capabilities, ensuring accuracy when used in future climate studies. The purpose of this research is to examine key features of the Asian monsoon simulated with the latest GFDL climate model, AM4, which will be used for the IPCC 6^th Assessment Report, through comparison of the simulations with observations from literature. The Asian monsoon, occurring during the summer, is a critical feature of the densely-populated region’s hydroclimate, responsible for 50-70% of its annual rainfall. Results show that the model is capable of producing the “eddy shedding” phenomenon, characterized by the quasi-periodic formation of westward propagating disturbances emanating from the summertime Tibetan upper-tropospheric anticyclone. This phenomenon forms the basis of the main intra-seasonal variability mode of the circulation in the region. However, the impact of “eddy shedding” on the surface hydroclimate, specifically the export of moisture from the Indian subcontinent to the Southwestern Tibetan Plateau, is not as clean-cut as suggested by recent literature. This work highlights the utility and limitation of climate models in better understanding regional climate variability and change.