Recent advances in the dynamics of extreme climate events driven by three-dimensional atmospheric circulation patterns

<p indent="0mm">In recent years, the mid-high latitudes of the Northern Hemisphere have experienced frequent extreme events that have led to devastating disasters. For example, in early summer 2020, the Yangtze River Basin experienced the most severe Meiyu rainfall in recent decades, whereas in August 2022, the Northern Hemisphere endured the most extreme heatwave in observational records. These extreme events have resulted in substantial economic losses and have posed significant risks to human health. Consequently, elucidating the dynamical mechanisms underlying the initiation and evolution of such extreme events remains an issue at the forefront in atmospheric science. To investigate the dynamical mechanisms governing such extremes, it is imperative to systematically characterize the three-dimensional structure of associated atmospheric circulation anomalies. However, conventional atmospheric dynamical frameworks, which are premised on the quasi-horizontal and non-divergent characteristics of midlatitude circulations, inherently fail to comprehensively elucidate the pivotal role of local vertical motion anomalies in modulating the evolution of extreme events. As part of this challenge, a three-pattern decomposition of global atmospheric circulation (3P-DGAC) model, which systemically unifies the global circulation through orthogonal decomposition into horizontal, meridional overturning, and zonal overturning components, has been pioneered. This three-dimensional decomposition framework enables rigorous quantification of local three-dimensional atmospheric circulation. Currently, this theoretical method has achieved significant progress in the fields of climate dynamics and the dynamics of extreme events. This paper provides a comprehensive review of the application of the 3P-DGAC method in research on extreme event dynamics. In the dynamical study of multiple recent occurrences of extreme events, the 3P-DGAC model effectively captures structural features of three-dimensional circulation, especially the local meridional and zonal circulations in mid-high latitudes. Moreover, the use of the model successfully elucidates the dominant atmospheric circulation patterns behind these extreme events, providing a reliable basis for subsequent dynamic research. For example, in a dynamical investigation of the August 2022 extreme heatwave in China, diagnostic analysis using the 3P-DGAC model revealed that in addition to the strong anticyclonic high in the mid-to-upper troposphere, local vertical circulations played critical roles. Specifically, the local meridional circulation dominated in the middle–lower Yangtze River Basin, whereas the extreme temperatures over the Tibetan Plateau were associated primarily with the local zonal circulation anomalies. These characteristics are difficult to reveal through traditional two-dimensional circulation decomposition methods. Importantly, elucidating dominant atmospheric circulation patterns not only enhances the accuracy and objectivity of identifying and extracting relevant external forcing factors, but also facilitates a clearer understanding of the physical mechanisms through which external forcing signals modulate changes in the spatial modes of atmospheric circulation, thereby influencing extreme events. In addition, the 3P-DGAC model is applicable to evaluating the dynamics of extreme weather events, such as cold waves. The model can effectively represent the evolution and interactions of horizontal, meridional, and zonal circulations during cold waves, providing new insights into the evolutionary process of atmospheric circulation during these events. In summary, these studies have developed a relatively established theoretical framework for studying the three-dimensional dynamics of extreme events on the basis of the 3P-DGAC model. This framework integrates the characteristics of extreme events with their dominant atmospheric circulation patterns, and reveals key climate variables and nonlinear interactions of three-dimensional atmospheric circulation. By enhancing our understanding of the mechanisms of the formation and development of extreme events, this framework not only provides a vital theoretical basis for improving climate models and predictions but also profoundly influences future research on the atmospheric circulation dynamics of extreme events.