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| Statistical Reconstruction of the Antarctic Oscillation Index Based on Multiple Proxies |
| ZHANG Zi-Yin,GONG Dao-Yi,HE Xue-Zhao,LEI Yang-Na,FENG Sheng-Hui |
| 1. State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China;2. Beijing Climate Center, Beijing 100089, China,1. State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China,1. State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China,3. Shaanxi Provincial Climate Center, Xi an 710014, China,1. State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China |
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Abstract Based on multiple proxies from the Southern Hemisphere, an austral summer (December-January-February: DJF) Antarctic Oscillation Index (AAO) since 1500 A.D. was reconstructed with a focus on interannual to interdecadal variability (< 50 a). By applying a multivariate regression method, the observational AAO-proxy relations were calibrated and cross-validated for the period of 1957-89. The regressions were employed to compute the DJF-AAO index for 1500-1956. To verify the results, the authors checked the explained variance (r2), the reduction of error (RE), and the standard error (SE). Cross-validation was performed by applying a leave-one-out validation method. Over the entire reconstruction period, the mean values of r2, RE, and SE are 59.9%, 0.47, and 0.67, respectively. These statistics indicate that the DJF-AAO reconstruction is relatively skillful and reliable for the last ~460 years. The reconstructed AAO variations on the interannual and interdecadal timescales compare favorably with those of several shorter sea level pressure (SLP)-based AAO indices. The leading periods of the DJF-AAO index over the last 500 years are ~2.4, ~2.6, ~6.3, ~24.1, and ~37.6 years, all of which are significant at the 95% level as estimated by power spectral analysis.
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Received: 28 August 2010
Revised: 08 September 2010
Accepted: 08 September 2010
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