Department of Geological Sciences, University of Colorado, Boulder, CO 80305, USA.
Sci Total Environ. 2011 Apr 15;409(10):1836-42. doi: 10.1016/j.scitotenv.2011.02.009. Epub 2011 Feb 26.
Soil water content strongly affects permafrost dynamics by changing the soil thermal properties. However, the movement of liquid water, which plays an important role in the heat transport of temperate soils, has been under-represented in boreal studies. Two different heat transport models with and without convective heat transport were compared to measurements of soil temperatures in four boreal sites with different stand ages and drainage classes. Overall, soil temperatures during the growing season tended to be over-estimated by 2-4°C when movement of liquid water and water vapor was not represented in the model. The role of heat transport in water has broad implications for site responses to warming and suggests reduced vulnerability of permafrost to thaw at drier sites. This result is consistent with field observations of faster thaw in response to warming in wet sites compared to drier sites over the past 30 years in Canadian boreal forests. These results highlight that representation of water flow in heat transport models is important to simulate future soil thermal or permafrost dynamics under a changing climate.
土壤含水量通过改变土壤热特性强烈影响多年冻土动态。然而，在北方地区的研究中，对液态水的迁移（液态水在中纬度土壤的热量传输中起着重要作用）重视不够。对具有和不具有对流传热的两种不同热传输模型与四个具有不同林龄和排水等级的北方站点的土壤温度测量值进行了比较。总体而言，当模型中没有代表液态水和水蒸气的迁移时，在生长季节土壤温度往往会高估 2-4°C。水的热传输作用对站点对变暖的响应具有广泛的影响，这表明在干燥的地方，多年冻土对融化的脆弱性降低。这一结果与过去 30 年来加拿大北方森林中较湿润地区比干燥地区变暖时更快融化的实地观测结果一致。这些结果强调，在变化的气候下，为了模拟未来土壤热或多年冻土动态，在热传输模型中代表水流是很重要的。
