The Arctic Oscillation in Coupled Climate Models

• Published in: Chinese Journal of Geophysics
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2008
• Subjects: Arctic; Pacific
• Online Access: http://dx.doi.org/10.1002/cjg2.1214; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fcjg2.1214; https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/cjg2.1214

Abstract This study investigates winter (JFM) Arctic Oscillation (AO) simulated by 23 global coupled climate models participating in the project “Twentieth‐Century Climate in Coupled Models” organized by IPCC AR4. Results show that almost all of the models capture the AO as the leading mode of the interannual variability for the extratropical atmosphere in the Northern Hemisphere. In most models, the North Pacific center of the AO mode is more pronounced in comparison with the observation. Such bias can be reduced with higher horizontal resolution of the AGCM, deriving from the intercomparison between two pairs of coupled models. None of the models can reproduce the upward trend of the AO index as strong as that observed in recent decades. Significant correlation of the AO index between the simulated and the observed only appears in two models (ECHO‐G and UKMO‐HadGEM1). Anomalies of the zonal mean zonal wind associated with the positive phase of the AO exhibit a dipole in the latitude, with westerly in the middle‐high latitudes and easterly in the subtropical area. Such features can be generated in most of the models (20/21), although the ability of some models in simulating the AO feature in the stratosphere needs to be improved. The models with good performances in reproducing the vertical structure of the AO, for example, CCSM3, MRI‐CGCM2.3.2, and UKMO‐HadGEM1, can reasonably simulate the cooling stratosphere in the North Polar and the warming troposphere in the midlatitude at the positive phase of the AO. The majority of the models reproduce the significant influence of the AO on the temperature and the precipitation over the Eurasian continent. Several models can simulate the relationship between the AO and the East Asian climate to a certain extent. Overall, the model UKMO‐HadGEM1 performs best among all the models in simulating the basic features of the AO. The above results provide a certain reference basis for the further improvement of the coupled models' capability in reproducing the AO. They are also ...