Can reducing the incoming energy flux over the Southern Ocean in a CGCM improve its simulation of tropical climate?

• Published in: Geophysical Research Letters
• Main Authors: Mechoso, Carlos R., Losada, Teresa, Koseki, S., Mohino, Elsa, Keenlyside, N., Castaño-Tierno, Antonio, Myers, T. A., Rodríguez-Fonseca, Belén, Toniazzo, T.
• Format: Article in Journal/Newspaper
• Language: English
• Published: John Wiley & Sons 2016
• Subjects: GCMs; ITCZ; Low clouds; Southern Ocean
• Online Access: http://hdl.handle.net/10261/141534; https://doi.org/10.1002/2016GL071150

Atmosphere-ocean general circulation models (CGCMs) show important systematic errors. Simulated precipitation in the tropics is generally overestimated over the oceans south of the equator, and stratocumulus (SCu) clouds are underestimated above too warm sea surface temperatures (SSTs). In the extratropics, SSTs are also too warm over the Southern Ocean. We argue that ameliorating these extratropical errors in a CGCM can result in an improved model's performance in the tropics depending upon the success in simulating the sensitivity of SCu to underlying SST. Our arguments are supported by the very different response obtained with two CGCMs to an idealized reduction of solar radiation flux incident at the top of the atmosphere over the Southern Ocean. It is shown that local perturbation impacts are very similar in the two models but that SST reductions in the SCu regions of the southern subtropics are stronger in the model with the stronger SCu-SST feedbacks. NOAA's Climate Program Office, Climate Variability and Predictability Program Award. Grant Number: NA14OAR4310278. European Union Seventh Framework Programme. Grant Numbers: FP7/2007–2013, 60352 Peer reviewed