Sensitivity to Glacial Forcing in the CCSM4
Sensitivity to Glacial Forcing in the CCSM4
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DOI：
10.1175/jcli-d-11-00416.1
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发表时间：
2013-03-01
影响因子：
4.9
通讯作者：
Rosenbloom, Nan
中科院分区：
文献类型：
--
作者：
Brady, Esther C.;Otto-Bliesner, Bette L.;Rosenbloom, Nan
结果来自社区气候系统模式第4版（CCSM 4），模拟末次冰期最大值（LGM），来自耦合模式相互比较项目（CMIP 5）第5阶段，分辨率为标准18，与CCSM 4 CMIP 5对历史和未来预测情景的大多数长期模拟相同。该模拟的强迫和边界条件遵循古气候建模相互比较项目第3版（PMIP 3）的协议。还分析了另外两个CCSM4 CO2敏感性模拟，其中浓度在模拟开始时突然改变为低185 ppm LGM浓度（LGMCO（2））和工业化前浓度的四倍（4xCO（2））。对于完整的LGM模拟，全球年平均地表温度的估计平衡冷却为5.5摄氏度，估计辐射强迫为-6.2 W m（-2）。辐射强迫包括末次冰期温室气体减少、冰盖、海平面比现在下降约120 m的大陆分布以及轨道参数的影响，但不包括大气气溶胶或植被生物地理学的变化。LGM模拟的平衡气候敏感性（ECS）为3.1（+/-0.3）摄氏度，与CCSM4 4xCO（2）结果相当。LGMCO（2）模拟显示更大的ECS为4.2 ℃。在CCSM 4中LGM发现的其他响应包括全球降水率以类似于2%摄氏度的速度下降，类似于政府间气候变化专门委员会第四次评估报告中的气候变化模拟（IPCC AR4）;大西洋纬向翻转环流（AMOC）的加强北大西洋深水变浅，南极底层水填充深盆地到窗台深度;以及增强的季节性循环，伴随着东太平洋SST的ENSO变率降低。
Results are presented from the Community Climate System Model, version 4 (CCSM4), simulation of the Last Glacial Maximum (LGM) from phase 5 of the Coupled Model Intercomparison Project (CMIP5) at the standard 18 resolution, the same resolution as the majority of the CCSM4 CMIP5 long-term simulations for the historical and future projection scenarios. The forcings and boundary conditions for this simulation follow the protocols of the Paleoclimate Modeling Intercomparison Project, version 3 (PMIP3). Two additional CCSM4 CO2 sensitivity simulations, in which the concentrations are abruptly changed at the start of the simulation to the low 185 ppm LGM concentrations (LGMCO(2)) and to a quadrupling of the preindustrial concentration (4xCO(2)), are also analyzed. For the full LGM simulation, the estimated equilibrium cooling of the global mean annual surface temperature is 5.5 degrees C with an estimated radiative forcing of -6.2 W m(-2). The radiative forcing includes the effects of the reduced LGM greenhouse gases, ice sheets, continental distribution with sea level lowered by approximately 120 m from the present, and orbital parameters, but not changes to atmospheric aerosols or vegetation biogeography. The LGM simulation has an equilibrium climate sensitivity (ECS) of 3.1(+/-0.3)degrees C, comparable to the CCSM4 4xCO(2) result. The LGMCO(2) simulation shows a greater ECS of 4.2 degrees C. Other responses found at the LGM in CCSM4 include a global precipitation rate decrease at a rate of similar to 2% degrees C-1, similar to climate change simulations in the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4); a strengthening of the Atlantic meridional overturning circulation (AMOC) with a shoaling of North Atlantic Deep Water and a filling of the deep basin up to sill depth with Antarctic Bottom Water; and an enhanced seasonal cycle accompanied by reduced ENSO variability in the eastern Pacific Ocean's SSTs.