Mid‐Holocene frozen ground in China from PMIP3 simulations
Mid‐Holocene frozen ground in China from PMIP3 simulations
复制标题
PMIP3模拟的中国全新世中期冻土
作者：
Yeyi Liu;D. Jiang
基于稀疏的代用资料，人们普遍认为中全新世冻土发生了大面积退化。本文采用古气候模拟对比项目第3期的模拟土壤温度来解决中国的这一问题。这种变化与轨道引起的日晒变化密切相关。在数量上，中国东北的多年冻土区面积减少了0.02×106 km2，以响应轨道引起的北方夏季日晒增加，但增加了0。不同位置的活动层厚度变化值差异很大。中国季节性冻土总体未见退化。从区域上看，在长江中下游附近，其覆盖面积增加了0.21×106 km2。此外，由于冬季普遍降温，季节性霜冻的最大穿透深度平均比工业化前深8.5 cm。冻土层的变化在各模型中是一致的。然而，模型不仅在冻土变化方面与代理数据不一致，而且在气候变化方面也与代理数据不一致。进一步的建模改进和充分的代理数据都需要填补模型和我们对中全新世冻土知识的数据之间的空白。
Extensive degradation of frozen ground in the mid‐Holocene is widely assumed on the basis of sparse proxy data. Here, the simulated soil temperature from the Paleoclimate Modelling Intercomparison Project Phase 3 is used to address this issue over China. By comparing with the results of a preindustrial (0 ka, baseline) simulation, we show that frozen ground in the mid‐Holocene (6 ka) simulation is degraded mainly in northeast China and on the northern Tibetan Plateau. The change follows closely orbitally induced variations in insolation. Quantitatively, permafrost area reduces by 0.02×106 km2 in northeast China in response to an orbitally induced increase in boreal summer insolation but increases by 0.08×106 km2 on the southern Tibetan Plateau due to local summer cooling. Changing values of active layer thickness vary greatly amongst different locations. On average, they are 3 and 4 cm thicker than the preindustrial values in northeast China and on the Tibetan Plateau, respectively. No degradation in seasonally frozen ground is detected over China as a whole. Regionally, its coverage increases by 0.21×106 km2 near the middle and lower reaches of the Yangtze River valley. In addition, the maximum depth of seasonal frost penetration is on average 8.5 cm deeper than preindustrial values due to widespread winter cooling. The changes in frozen ground are consistent amongst models. However, the models disagree with proxy data in terms of not only the changes in frozen ground but also climate. Further modelling improvements and adequate proxy data are both needed to fill in the gaps between models and the data in our knowledge of the mid‐Holocene frozen ground.
影响因子：
14.6
作者：
Martijn Gough
通讯作者：
Martijn Gough