Abstract

Recent paleoclimate proxy reconstructions show that tropical surface temperatures may have been as high as 35°–40°C in the Early Cenozoic. Here, we study the tropical atmospheric circulation's response to temperatures in this range using a full-complexity atmospheric general circulation model (AGCM). We find that when equatorial surface temperatures exceed ∼33°C, the model undergoes a transition to equatorial superrotation, a state with strong annual- and zonal-mean westerlies on the equator. The transition is driven by zonal momentum convergence due to large-amplitude transient eddies on the equator. These eddies have a structure similar to the observed Madden-Julian Oscillation (MJO). The model's MJO variability is weaker than observed when simulating the modern climate but increases sharply with temperature, coming to dominate the tropical variability and mean state of the warmest climates.

Comments

An edited version of this paper was published by AGU. Copyright (2010) American Geophysical Union.

Rodrigo Caballero, Matthew Huber, (2010), Spontaneous transition to superrotation in warm climates simulated by CAM3, Geophysical Research Letters, Vol 37, 10.1029/2010GL043468. To view the published open abstract, go to http://dx.doi.org and enter the DOI.

Keywords

superrotation, MJO

Date of this Version

2010

DOI

10.1029/2010GL043468

Volume

37

Issue

11

Pages

L11701

Link Out to Full Text

http://www.agu.org/pubs/crossref/2010/2010GL043468.shtml

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