Three Regimes of Temperature Change Over Dry Land, Moist Land, and Oceanic Surfaces

Monday, Jan 11, 2021

Previous studies report that extreme temperature events will occur more often and become more extreme in the future, yet there is no consensus on how much this increased likelihood of extreme heat events is due to a shift of temperature distribution mean or a changed temperature distribution shape. In a recent paper, led by AOS postdoc Suqin Duan, with coauthors Kirsten Findell, a GFDL physical scientist, and Jonathon Wright, a faculty member in Tsinghua University, the authors compared spatial patterns of summertime mean and extreme warming, and found local temperature distribution changes can be summarized into three regimes according to surface properties: dry land exhibits a shift of the entire distribution with pronounced warming in the mean; moist land shows a smaller change in the mean compared with dry land but features an elongated upper tail relative to the mean; oceanic surface shows a smaller shift in the mean relative to land surface, with no significant elongation of the upper tail. The elongated upper tail over moist land indicates an amplified warming of extreme hot days. This amplified extreme warming over moist land is compounded on top of the land-ocean contrast in mean warming, and is related to suppressed evaporation and associated land surface feedbacks. This paper is published in GRL.