Holocene climate evolution in the high-latitude Southern Hemisphere simulated by a coupled atmosphere-sea ice-ocean-vegetation model
Holocene climate evolution in the high-latitude Southern Hemisphere simulated by a coupled atmosphere-sea ice-ocean-vegetation model
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大气-海冰-海洋-植被耦合模型模拟南半球高纬度全新世气候演化
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发表时间：
2005
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影响因子：
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通讯作者：
N. Koç
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作者：
H. Renssen;H. Goosse;T. Fichefet;V. Masson‐Delmotte;N. Koç
全新世气候模拟9000年长的瞬态实验与ECBilt-CLIO-VECODE耦合大气-海冰-海洋-植被模式。这个实验是被迫与每年变化的轨道参数和大气中的CO2和CH 4浓度。目的是研究这些长期强迫对南半球高纬地区不同季节地表温度演变的影响。我们发现夏季的热最佳时期是全新世中期（6-3 ka BP），局部温度比工业化前平均温度高3°C。在秋季，气温经历了长期的上升，特别是在最初的几千年。冬季和春季的模拟趋势相反，冬季南大洋在9 ka BP时相对温暖（比工业化前平均值高出3.5°C），春季大陆温暖（+3 ° C），随后逐渐冷却到现在。这些长期的温度趋势可以用以下两个因素的组合来解释：（1）对轨道强迫的延迟反应，由于系统的热惯性，温度滞后于日照1至2个月，以及（2）南大洋的长期记忆。这种长记忆与温暖的晚冬-春异常储存在夏季较浅的混合层以下，直到下一个冬天。海冰作为一个放大因子，通过冰-水反馈和冰-绝缘反馈起着重要的作用。我们的实验可以帮助我们提高对代理全新世信号的理解。例如，结果表明，与最近的主张相反，与北方半球的遥相关似乎不一定能解释全新世南半球温度变化的历史。
The Holocene climate is simulated in a 9000-yr-long transient experiment performed with the ECBilt-CLIO-VECODE coupled atmosphere-sea ice-ocean-vegetation model. This experiment is forced with annually varying orbital parameters and atmospheric concentrations of CO2 and CH4. The objective is to study the impact of these long-term forcings on the surface temperature evolution during different seasons in the high-latitude Southern Hemisphere. We find in summer a thermal optimum in the midHolocene (6-3 ka BP), with temperatures locally 3°C above the preindustrial mean. In autumn the temperatures experienced a long-term increase, particularly during the first few thousand years. The opposite trend was simulated for winter and spring, with a relatively warm Southern Ocean at 9 ka BP in winter (up to 3.5°C above the preindustrial mean) and a warm continent in spring (+3°C), followed by a gradual cooling towards the present. These long-term temperature trends can be explained by a combination of (1) a delayed response to orbital forcing, with temperatures lagging insolation by 1 to 2 months owing to the thermal inertia of the system, and (2) the long memory of the Southern Ocean. This long memory is related to the storage of the warm late winter-spring anomaly below the shallower summer mixed layer until next winter. Sea ice plays an important role as an amplifying factor through the ice-albedo and ice-insulation feedbacks. Our experiments can help to improve our understanding of the Holocene signal in proxies. For instance, the results suggest that, in contrast to recent propositions, teleconnections to the Northern Hemisphere appear not necessarily to explain the history of Southern Hemisphere temperature changes during the Holocene.