Regional Perspective of Hadley Circulation and Its Uncertainties among Different Datasets: Biases of ENSO-Related Hadley Circulation in CMIP Models

The Hadley Circulation (HC), a fundamental component of global atmospheric circulation, plays an important role in the global energy balance and transport of moisture. The interaction between ENSO and the HC significantly impacts tropical climate and has broad implications for global climate variability through atmospheric teleconnections. The HC is usually represented by the mass stream function. As a result, it can rarely be observed through in-situ measurement. Reanalysis datasets and CMIP models are frequently used to investigate the properties of the HC. Previous studies systematically assess the capability of these CMIP models to represent the spatial distribution and intensity of the HC anomalies associated with ENSO events. However, most of these studies investigate the HC anomaly from a global perspective. In this work, we focus on evaluating the ability of CMIP6 models to capture the three-dimensional features of ENSO-related HC anomalies in comparison to that in six reanalysis datasets. Results show a consistent westward shift of the ENSO-related HC over the tropical Central-Eastern Pacific in almost all CMIP6 models, accompanied by a weakening of the asymmetric component of the ENSO-related HC over the equatorial Pacific. The former is mainly attributed to the westward extension of the Pacific cold tongue in CMIP models, while the latter is more related to the southward shift of the ENSO-related SST and precipitation anomalies in CMIP models. One should be aware of these biases when studying the ENSO-related atmospheric circulation changes. Our study has broad implications for ENSO simulations and the predictability of ENSO-related global climate variabilities.