Blog Archive

Friday, August 13, 2010

Spontaneous transition to superrotation in warm climates simulated by CAM3

Geophysical Research Letters, 37 (2010) L11701; doi: 10.1029/2010GL043468.

Spontaneous transition to superrotation in warm climates simulated by CAM3

Rodrigo Caballero (Meteorology and Climate Centre, School of Mathematical Sciences, University College Dublin, Dublin, Ireland) and  Matthew Huber (Earth and Atmospheric Sciences, Purdue University, West Lafayette, IN, USA)


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.

Citation: Caballero, R. & M. Huber (2010), Spontaneous transition to superrotation in warm climates simulated by CAM3, Geophys. Res. Lett., 37, L11701; doi: 10.1029/2010GL043468. 


jyyh said...

Again one of these articles of general interest, that is for registered members only. Thank you for finding & keeping references.

Tenney Naumer said...

Thanks, it looked kinda cool, sorry there is no way to look at the whole article.

Anonymous said...

If I remember correctly CAM3 has been one of the more reliable models on tropical areas. So this result (whatever it is, on the whole article) is of particular relevance & interest for local climate prediction in tropics. In combination of the observed enlargement and slight northward shift of the Hadley cell, this result might end up as being much cited in the future journals of tropical climatology regarding predictions, imho.

Regards, jyyh