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随着全球气候变暖,青藏高原冻土活动层正在逐渐加深,为了理解积雪和表层有机质土壤对冻土活动层的影响机理,一维水热耦合模型CoupModel被用于模拟气象驱动下土壤冻融的动态过程.基于祁连山冰沟和青藏高原唐古拉站长期监测数据,CoupModel模型被成功的率定和验证.在冰沟站验证的模型被用于研究积雪对冻土活动层的影响,结果显示:目前较浅积雪情景(雪深<20cm)比完全忽略积雪的情景模拟的冬季土壤冻结深度深,说明青藏高原现状下较浅的积雪有利于冻土发育.原因是雪面较高的反照率造成地表吸收的太阳辐射减少,导致雪面温度较低,加之浅雪的阻热性能又较小,综合导致浅雪覆盖时表层土壤向大气释放的能量增加.但随着积雪深度逐渐增加,模拟的冬季土壤冻结深度反而越来越浅,说明较厚的积雪(>20cm的雪深)并不利于冻土的发育,主要是雪相对于空气低的热传导隔绝了表层土壤向大气的热损失.在唐古拉站验证的模型被用于研究有机质土对冻土活动层的影响,结果显示:随着有机质土壤深度增加,模拟的活动层夏季融化深度逐渐较小.有机质土壤较矿物质土壤低的热传导和高的热容性质减少了下伏土壤热状况对太阳辐射和气温波动的响应,说明有机质土有利于冻土的保护.
With global warming, the active layer of permafrost in the Qinghai-Tibet Plateau is gradually deepening. In order to understand the mechanism of the influence of snow and surface organic matter on the active layer of frozen soil, a one-dimensional water-heat coupling model, CoupModel, is used to simulate the weather- Based on the long-term monitoring data of the ice trough in Qilian and Tanggula station of Qinghai-Tibet Plateau, the CoupModel model was successfully calibrated and validated.The model verified in Binggou Station was used to study the influence of snow on the active layer of frozen soil. The result It shows that the current shallow snow cover (snow depth <20 cm) is deeper than the winter frozen cover depth, which completely ignores the snow cover scenario, indicating that the shallow snow cover in the Tibetan Plateau is favorable for the development of the frozen ground due to the snow surface more The high albedo decreases the solar radiation absorbed by the surface, resulting in a lower temperature of the snow surface and less heat resistance of the shallow snow, resulting in an increase in the energy released by the surface soil to the atmosphere when covered with shallow snow. However, Depth gradually increased, but the simulated winter soil freezing depth was more and more shallow, indicating that thick snow (> 20cm snow depth) is not conducive to the development of frozen soil, mainly snow relative to low heat transfer The heat loss to the atmosphere from the topsoil was insulted.The model verified in Tangula Station was used to study the effect of organic matter on the active layer of the frozen soil.The results showed that the depth of summer thawing of the simulated active layer gradually increased as the soil depth increased The lower heat transfer and higher heat capacity of organic soils than mineral soils reduced the response of underlying soils to solar radiation and temperature fluctuations, indicating that organic soils are good for the protection of frozen soils.