Stellar absorption aloft shifts meridional heat transport into middle atmospheres

by Dr Bowen Fan(樊博文) (Yale University)

Friday 16 Oct 2026, 10:00 → 11:00 Asia/Shanghai

Tsung-Dao Lee Institute/S4F-SW - Open Area (Tsung-Dao Lee Institute)

Host: Xianyu Tan
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Abstract:
Atmospheric heat transport reduces temperature differences between low and high latitudes, but need not occur near the surface. On Earth, surface stellar absorption and evaporation support transport mainly in the troposphere. We test whether strong stellar absorption aloft instead favors transport in the middle atmosphere, using Titan climate-model experiments, Venus climate-model data and a Mars reanalysis. On Titan, the middle atmosphere carries 43% of the poleward heat transport despite containing only 3% of the atmospheric mass. Increasing haze shortwave absorption from 0.25x to 4x raises this fraction from 32% to 60%, with circulation changes accounting for most of the response. On Venus, 87% of poleward transport occurs within and above the clouds. During two Martian global dust storms, the middle-atmospheric share of northward transport rises from 10% to 15% and from 16% to 23% relative to matched quiet seasons. These results show how stellar light absorbed aloft with strong latitudinal gradients can sustain substantial heat transport in a small fraction of atmospheric mass, separating atmospheric heat redistribution on terrestrial planets from surface-driven circulation.

Biography:
Dr. Fan received a liberal education at Yuanpei College and earned a B.S. in Physics from Peking University, Ph.D. in Geophysical Sciences at the University of Chicago. In 2025, he joined Yale as a Skinner postdoc. He is broadly interested in planetary science and climate science. The intersection of these fields offers rich opportunities to explore physical problems including fluid dynamics, radiative transfer, and phase transitions. His Ph.D. research focuses on the thermal structure and hydrological cycles of arid planets (e.g., early Mars, Titan) and hot planets (e.g., early Venus, early Earth). Beyond his thesis work, he has contributed to studies on snowball Earth, lava exoplanets, and future Mars.