Midlatitude heat extremes, soil moisture, and planetary waves

As one of the deadliest natural phenomena on Earth, heat waves and their impacts are likely to get stronger in the future under climate change. Understanding their mechanisms and improving the skill of their prediction at extended range have become urgent tasks for climate scientists. The role of land-atmosphere interactions in subseasonal-to-seasonal (S2S) predictions has emerged as an important but fundamentally challenging problem. As the midlatitudes get warmer and drier due to climate change, the role of soil moisture may become even more prominent in some semi-arid areas, such as the Great Plains. In order to further establish the causal relationship between soil moisture, US heat waves and Rossby wave trains, Teng et al. (2019) have carried out some idealized prescribed soil moisture experiments with the CESM. The results suggest that terrestrial heating anomalies due to the increasing aridity in the Great Plains can cause not only local heat waves, but also hemispheric wide impacts.

Reference

  • Teng, H., G. Branstator, A. B. Tawfik, P. Callaghan, 2019: Circumglobal response to prescribed soil moisture over North America. J. Climate, 32,4525-4545.