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Author Zi-Yin Zhang |
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Has the Drake Passage Played an Essential Role in the Cenozoic Cooling?
Atmospheric and Oceanic Science Letters, Volume 3 Number 5. Zhang Zi-Yin; Gong Zhong-Shi; Yan Qing; et al. - Science Press, 2010The Drake Passage is the seaway between South America and Antarctica. It is widely believed that the thermal isolation effects caused by the opening of the Drake Passage played an important role in the abrupt cooling that occurred at the Eocene-Oligocene boundary in the Cenozoic. These effects are also thought to be independent of the geometry of the passage. Here, the authors demonstrate that the climate impacts of the Drake Passage depend on the passage geometry by comparing the climate’s sensitivity to the opening of the Drake Passage under the present and the Early Eocene land-sea configur ...
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Available online: http://www.iapjournals.ac.cn/aosl/ch/reader/view_abstract.aspx?file_no=AOSL10054
in Atmospheric and Oceanic Science Letters > Volume 3 Number 5 (16 September 2010) . - p.288-292The Drake Passage is the seaway between South America and Antarctica. It is widely believed that the thermal isolation effects caused by the opening of the Drake Passage played an important role in the abrupt cooling that occurred at the Eocene-Oligocene boundary in the Cenozoic. These effects are also thought to be independent of the geometry of the passage. Here, the authors demonstrate that the climate impacts of the Drake Passage depend on the passage geometry by comparing the climate’s sensitivity to the opening of the Drake Passage under the present and the Early Eocene land-sea configurations. These experiments show that the thermal isolation effects caused by the passage are much stronger under the present land-sea configuration. In comparison, under the Early Eocene land-sea configuration, the weak anomalies in heat transport caused by the opening of the narrow and shallow Drake Passage are not strong enough to thermally insulate Antarctica. The climate effects of the Drake Passage on the Cenozoic cooling have been overestimated in previous sensitivity studies carried out using the present land-sea configuration. Thus, it is unlikely that the opening of the Drake Passage played an essential role in the abrupt Cenozoic cooling, especially in the abrupt cooling at the Eocene-Oligocene boundary.
Language(s): English
Format: Digital (Free), Hard copyTags: Antarctica ; Melting Ice ; Paleoclimatology ; Research
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Statistical Reconstruction of the Antarctic Oscillation Index Based on Multiple Proxies
Atmospheric and Oceanic Science Letters, Volume 3 Number 5. Zhang Zi-Yin; Gong Dao-Yi; He Xue-Zhao; et al. - Science Press, 2010Based 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-va ...
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Available online: http://www.iapjournals.ac.cn/aosl/ch/reader/view_abstract.aspx?file_no=AOSL10053
Zi-Yin Zhang ; Dao-Yi Gong ; Xue-Zhao He ; Yang-Na Lei ; Sheng-Hui Feng
in Atmospheric and Oceanic Science Letters > Volume 3 Number 5 (16 September 2010) . - p.283-287Based 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.
Language(s): English
Format: Digital (Free), Hard copyTags: Meteorology ; Antarctic Oscillation (AAO) ; Research ; Numerical simulation
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