Last glacial maximum constraints on the Earth System model HadGEM2-ES
Last glacial maximum constraints on the Earth System model HadGEM2-ES
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DOI：
10.1007/s00382-014-2421-0
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发表时间：
2015-09-01
期刊：
影响因子：
4.6
通讯作者：
Valdes, Paul J.
中科院分区：
文献类型：
--
作者：
Hopcroft, Peter O.;Valdes, Paul J.
我们调查的大气和陆地表面组件的CMIP 5/AR 5地球系统模型HadGEM 2-ES工业化前（PI：AD 1860）和末次冰期最大（LGM：21 kyr）边界条件的响应。HadGEM 2-ES包括大气、海洋和海冰组成部分，这些组成部分与碳循环、气溶胶（包括矿物尘埃）和对流层化学的表现形式相互耦合。在这项研究中，我们专注于大气模式HadGEM 2-A耦合到陆地碳循环和气溶胶模式。这种配置是被迫与每月的海面温度和海冰场等效耦合模拟与旧版本的哈德利中心模型，HadCM 3。HadGEM 2-A模拟了北方大陆的极端冷却和亚洲植被的几乎完全消亡，与重建的表面温度和生物群落分布相比，LGM环境的代表性较差。与其前身AR 4模型HadCM 3 M2相比，该模型在LGM中的表现也明显较差。详细的分析表明，在HadGEM 2-A植被死亡背后的主要因素是一个微妙的变化，在HadGEM 2的物候模型的叶片死亡率的温度依赖性。这影响了雪植被覆盖和植被动态。一组新的参数进行了测试，工业化前和末次冰期，在这两个时间段的植被覆盖率大大提高，包括工业化前西伯利亚针叶林覆盖率的改进表示。新的参数和由此产生的全球植被分布的变化强烈影响模拟加载的矿物粉尘，一个重要的气溶胶末次冰期。还分析了突然的4倍工业化前CO2模拟的气候响应，并显示出对整个寒带地表温度的适度区域影响。
We investigate the response of the atmospheric and land surface components of the CMIP5/AR5 Earth System model HadGEM2-ES to pre-industrial (PI: AD 1860) and last glacial maximum (LGM: 21 kyr) boundary conditions. HadGEM2-ES comprises atmosphere, ocean and sea-ice components which are interactively coupled to representations of the carbon cycle, aerosols including mineral dust and tropospheric chemistry. In this study, we focus on the atmosphere-only model HadGEM2-A coupled to terrestrial carbon cycle and aerosol models. This configuration is forced with monthly sea surface temperature and sea-ice fields from equivalent coupled simulations with an older version of the Hadley Centre model, HadCM3. HadGEM2-A simulates extreme cooling over northern continents and nearly complete die back of vegetation in Asia, giving a poor representation of the LGM environment compared with reconstructions of surface temperatures and biome distributions. The model also performs significantly worse for the LGM in comparison with its precursor AR4 model HadCM3M2. Detailed analysis shows that the major factor behind the vegetation die off in HadGEM2-A is a subtle change to the temperature dependence of leaf mortality within the phenology model of HadGEM2. This impacts on both snow-vegetation albedo and vegetation dynamics. A new set of parameters is tested for both the pre-industrial and LGM, showing much improved coverage of vegetation in both time periods, including an improved representation of the needle-leaf forest coverage in Siberia for the pre-industrial. The new parameters and the resulting changes in global vegetation distribution strongly impact the simulated loading of mineral dust, an important aerosol for the LGM. The climate response in an abrupt 4x pre-industrial CO2 simulation is also analysed and shows modest regional impacts on surface temperatures across the Boreal zone.