Incorporating organic soil into a global climate model
Incorporating organic soil into a global climate model
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DOI：
10.1007/s00382-007-0278-1
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发表时间：
2008-02
期刊：
影响因子：
4.6
通讯作者：
D. Lawrence;A. Slater
中科院分区：
文献类型：
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作者：
D. Lawrence;A. Slater
有机物显著改变土壤的热和水力性质，但通常不包括在全球气候模型中使用的陆地表面方案中。这一遗漏对地面热量和湿度状况产生了影响，特别是在土壤碳含量普遍较高的高纬度地区。全球土壤碳数据被用来建立一个地理分布，剖面土壤碳密度数据集的社区土地模型（CLM）。CLM参数化土壤的热和水力特性进行修改，以适应矿物和有机土壤物质。包括有机土壤在内的离线模拟的特点是年平均土壤温度较低（土壤碳含量高的地区最高可达2.5°C）。夏季由于土壤热通量的调制，夏季降温强烈。冬季气温略高，因为有机土壤在秋季和冬季不能有效地冷却。有机土壤的高孔隙度和导水率导致土壤柱较湿润，但表层饱和度相对较低，土壤蒸发相应较低。当CLM耦合到社区大气模型，减少潜热通量驱动更深的边界层，相关的减少低云部分，和温暖的夏季气温在北极。最后，有机土壤的隔热性能降低土壤温度的年际变化，但只是轻微的。这一结果表明，虽然平均土壤温度的冷却将推迟模拟的日期，冻土开始解冻，有机质可能只提供有限的绝缘表面变暖。
Organic matter significantly alters a soil’s thermal and hydraulic properties but is not typically included in land-surface schemes used in global climate models. This omission has consequences for ground thermal and moisture regimes, particularly in the high-latitudes where soil carbon content is generally high. Global soil carbon data is used to build a geographically distributed, profiled soil carbon density dataset for the Community Land Model (CLM). CLM parameterizations for soil thermal and hydraulic properties are modified to accommodate both mineral and organic soil matter. Offline simulations including organic soil are characterized by cooler annual mean soil temperatures (up to ∼2.5°C cooler for regions of high soil carbon content). Cooling is strong in summer due to modulation of early and mid-summer soil heat flux. Winter temperatures are slightly warmer as organic soils do not cool as efficiently during fall and winter. High porosity and hydraulic conductivity of organic soil leads to a wetter soil column but with comparatively low surface layer saturation levels and correspondingly low soil evaporation. When CLM is coupled to the Community Atmosphere Model, the reduced latent heat flux drives deeper boundary layers, associated reductions in low cloud fraction, and warmer summer air temperatures in the Arctic. Lastly, the insulative properties of organic soil reduce interannual soil temperature variability, but only marginally. This result suggests that, although the mean soil temperature cooling will delay the simulated date at which frozen soil begins to thaw, organic matter may provide only limited insulation from surface warming.