The misrepresentation of Tropical SSTs in climate models
We provide important new evidence that a primary source of this error lies in the way an SST change in one tropical region affects and is affected by a change in another region in the models. Specifically, we estimated SST feedbacks among 8 geographically localized regions in the tropical Pacific, Indian, and Atlantic oceans from 3 observational datasets and 76 IPCC model simulations of the 20th century. The 8-dimensional SST feedback matrix in each case was obtained from a linear inverse model (LIM) constructed using observed or simulated monthly SST variations over the 100-yr period. The simulated feedback matrices were found to differ in several key respects from the observed matrices, and also from one another. For instance, the influence of the eastern Pacific ENSO region on other regions, and of the other regions on the ENSO region, was found to vary considerably from model to model. The varied representations of interactions with the Indo-Pacific Warm Pool region were also striking. Because the relatively short-term SST interactions investigated here occur primarily through the atmosphere, these results highlight the need to improve the representation of not only the local radiative-thermodynamic but also the remote atmospheric teleconnective feedbacks on tropical SSTs in climate models.