Using over a century of ground-based observations over the contiguous United States, we show that the frequency of compound dry and hot extremes has increased substantially in the past decades, with an alarming increase in very rare dry-hot extremes. Our results indicate that the area affected by concurrent extremes has also increased significantly. Further, we explore homogeneity (i.e., connectedness) of dry-hot extremes across space. We show that dry-hot extremes have homogeneously enlarged over the past 122 years, pointing to spatial propagation of extreme dryness and heat and increased probability of continental-scale compound extremes. Last, we show an interesting shift between the main driver of dry-hot extremes over time. While meteorological drought was the main driver of dry-hot events in the 1930s, the observed warming trend has become the dominant driver in recent decades. Our results provide a deeper understanding of spatiotemporal variation of compound dry-hot extremes.

通过对美国连续一个多世纪的地面观测，我们发现在过去的几十年中，极端干旱和极端高温的复合频率已大大增加，而非常罕见的极端极端干旱也令人震惊。我们的结果表明，受同时发生的极端影响的区域也显着增加。此外，我们探索了整个空间中干热极端的同质性（即连通性）。我们表明，在过去的122年中，干热极端已经均匀扩大，这表明极端干燥和高温的空间传播以及大陆尺度复合极端的可能性增加。最后，随着时间的推移，我们显示出干热极端的主要驱动因素之间的有趣变化。气象干旱是1930年代干热事件的主要驱动因素，近几十年来，观察到的变暖趋势已成为主导。我们的结果提供了对复合干热极端时空变化的更深刻理解。