For years, global climate models have shown biases in their representation of the Intertropical Convergence Zone (ITCZ), a tropical rainband where a large portion of Earth’s precipitation occurs. However, researchers from a recent Climate Observations and Monitoring (COM) Program- and Modeling, Analysis, Predictions and Projections (MAPP) Program-funded study argue that a significant portion of tropical rainfall and circulation biases in global climate models are due to how mountain ranges are represented in these models.
Their study, newly published in AGU Advances, demonstrates that current global climate models underestimate the height of mountain ranges. By raising the height of the Sierra Madre mountain range in Central America the researchers were able to significantly improve model simulations of climatological features such as the ITCZ and the El Niño–Southern Oscillation. This simple, physically-based method to improve climate models can also be applied to other mountainous regions such as the Rockies in North America.