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A Chinese Academy of Sciences El Niño-Southern Oscillation Model

Paper Reviewed
Su, T., Xue, F., Sun, H. and Zhou, G. 2015. The El Niño-Southern Oscillation cycle simulated by the climate system model of the Chinese Academy of Sciences. Acta Oceanologica Sinica 34: 55-65.

Working with a more than 200-year simulation of the climate system model of the Chinese Academy of Sciences (CAS-ESM-C), Su et al. (2015) write that they "evaluated the model performance in simulating the ENSO cycle, with a focus on the developing and decaying processes." And what did they thereby learn?

In the words of the four Chinese researchers, they say, compared with observations, that (1,2) "the simulated ENSO exhibits a much stronger amplitude and shorter period of 2-3 years," that (3) "the model overestimates the westerly anomaly in the equatorial western Pacific," that (4) "the El Niño tends to develop faster," along with (5) "a faster eastward propagation of the subsurface warm anomaly," that (6,7) "a cold water anomaly and an easterly anomaly are found in the western Pacific," that (8) "this mechanism is only effective for a strong El Niño event," that (9) "the response in the model occurs more frequently," due to (10) "an overestimated intensity of the El Niño," that (11) the "more frequent occurrence of the ENSO in the model is closely related to a shallower thermocline," which (12) "speeds up the zonal redistribution of the heat content in the upper Pacific Ocean," and that (13) "the shallower thermocline can be attributed to the weaker wind stress in the equator."

In light of this set of unfortunate findings, Su et al. thus -- and quite unsurprisingly -- conclude that "it is necessary to improve the wind bias in the model." And so it is.

Posted 5 May 2015