Evolution of the seasonal temperature cycle in a transient Holocene simulation: orbital forcing and sea-ice
Evolution of the seasonal temperature cycle in a transient Holocene simulation: orbital forcing and sea-ice
复制标题
DOI：
10.5194/cp-7-1139-2011
复制
发表时间：
2011-01-01
影响因子：
4.3
通讯作者：
Jungclaus, J. H.
中科院分区：
文献类型：
--
作者：
Fischer, N.;Jungclaus, J. H.
地球轨道的变化导致太阳辐射的季节性和季节性分布的变化。我们量化的影响，轨道引起的变化对季节性温度循环在过去6000年的瞬态模拟-从全新世中期到今天-使用耦合的大气-海洋环流模式（ECHAM 5/MPI-OM），包括陆面模式（JSBACH）。季节性温度循环直接响应几乎无处不在的日照变化。在北方半球，其振幅随着冬季日照的增加和夏季日照的减少而减小。在南半球，情况正好相反，在北冰洋，夏季日照减少导致海冰覆盖增加。海洋和大气之间的海冰的绝缘作用导致热通量减少，并在冬季有利于北冰洋的“大陆”条件，导致温度大幅下降。因此，有两种相互竞争的效应：对日照变化的直接反应和海冰隔热效应。海冰的隔热效果更强，因此北冰洋上空季节性温度循环的幅度增加。这种增加是最强的巴伦支大陆架和影响的温度响应在北方Europe.We比较我们模拟的季节性温度在欧洲的古重建。我们发现更好的协议，在冬季温度比夏季温度和更好的协议，在北方欧洲比在南欧，因为该模型不再现欧洲南部全新世夏季冷却推断从古重建。北方欧洲的温度重建支持海冰绝缘效应对季节温度循环演变的影响的概念。
Changes in the Earth's orbit lead to changes in the seasonal and meridional distribution of insolation. We quantify the influence of orbitally induced changes on the seasonal temperature cycle in a transient simulation of the last 6000 years - from the mid-Holocene to today - using a coupled atmosphere-ocean general circulation model (ECHAM5/MPI-OM) including a land surface model (JSBACH).The seasonal temperature cycle responds directly to the insolation changes almost everywhere. In the Northern Hemisphere, its amplitude decreases according to an increase in winter insolation and a decrease in summer insolation. In the Southern Hemisphere, the opposite is true.Over the Arctic Ocean, decreasing summer insolation leads to an increase in sea-ice cover. The insulating effect of sea ice between the ocean and the atmosphere leads to decreasing heat flux and favors more "continental" conditions over the Arctic Ocean in winter, resulting in strongly decreasing temperatures. Consequently, there are two competing effects: the direct response to insolation changes and a sea-ice insulation effect. The sea-ice insulation effect is stronger, and thus an increase in the amplitude of the seasonal temperature cycle over the Arctic Ocean occurs. This increase is strongest over the Barents Shelf and influences the temperature response over northern Europe.We compare our modeled seasonal temperatures over Europe to paleo reconstructions. We find better agreements in winter temperatures than in summer temperatures and better agreements in northern Europe than in southern Europe, since the model does not reproduce the southern European Holocene summer cooling inferred from the paleo reconstructions. The temperature reconstructions for northern Europe support the notion of the influence of the sea-ice insulation effect on the evolution of the seasonal temperature cycle.