Rodrigo Caballero 
Professor and Head, Department of Meteorology
Stockholm University, Sweden

Atmospheric superrotation at Earth's surface

Atmospheric superrotation refers to a state with prograde (i.e. westerly) zonal-mean winds at or near the equator. It is an observed feature of several planetary atmospheres, but does not occur on present-day Earth. The question of whether Earth could superrotate under altered climates has attracted attention in recent years and remains unresolved. Though an intriguing problem in geophysical fluid dynamics, superrotation is arguably of limited consequence for the broader climate system unless it is felt at the surface, where it can alter the ocean circulation and surface temperature patterns. In this talk, I will give a general discussion of superrotation and the mechanisms sustaining it. I will also explore whether superrotation can occur at the surface. I show that surface superrotation can occur both in theory and in practice across a hierarchy of Earth-like atmospheric models, albeit in a rather extreme parameter regime.

Caballero, R. and Carlson, H. (2018). Surface superrotation. J. Atmos. Sci., 75:3671–3689.
Tziperman, E. and Farrell, B. (2009). Pliocene equatorial temperature: Lessons from atmospheric superrotation. Paleoceanography, 24:PA1101.
Held, I. M. (1999). Equatorial superrotation in Earth-like atmospheric models. Bernhard Haurwitz Memorial Lecture, 23 pp. (Available online at www.gfdl.gov).