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东北多年冻土(除非指明是季节冻土,以下将多年冻土简称冻土)是中国第二大冻土分布区,主要发育“兴安-贝加尔型”冻土.由于处在欧亚大陆冻土区南缘,冻土的热稳定性差,寒区生态的敏感性强.在气候变暖条件下,冻土已经和正在发生着“三向”退化.为预测冻土南界和地温变化,根据47个气象站资料并在SHAW模型对植被影响地表温度修正的基础上,建立了冻土地表温度分布的等效纬度模型.结合非稳态热传导模型的有限元数值计算,以多模型结合的方法,进一步计算和分析了目前、50年和100年后冻土地温分区变化.结果表明,在目前地表温度为1.5℃范围,仍可残留冻土.以0.048℃a-1气温递增速率,在目前地表温度为0.5℃和-0.5℃的区域,50年和100年后各自仍有可能存在冻土;冻土面积将由现在的2.57×105 km2各自减至1.84×105和1.29×105 km2,分别减少28.4%和49.8%,且东部退化幅度大于西部.同时,区域地温升高,冻土厚度减薄;稳定型(年平均地温Tcp≤-1.0℃)冻土面积逐渐减小,将由现在的1.07×105 km2分别减少至8.8×104 km2(50年后)和5.6×104 km2(100年后).相应地,不稳定型(Tcp>-1.0℃)多年冻土和季节冻土的面积增加,冻土南界将显著北移.冻土环境的变化,将给东北寒区工程设施和生态环境带来重要影响.减少或避免人为地改变冻土赋存条件,是保护冻土环境较可行的途径.
Northeast permafrost (except for the specified permafrost, the permafrost hereinafter referred to as frozen soil) is China’s second largest frozen soil distribution area, mainly the development of “Xing An-Baikal type” permafrost. As in the Eurasian continent In the southern margin of the permafrost region, the thermal stability of the frozen soil is poor, and the ecological sensitivity in the cold area is strong. Under the conditions of climate warming, permafrost has been and is undergoing “three-way” degradation. Based on the data of 47 weather stations and the correction of the surface temperature affected by the SHAW model, an equivalent latitude model of the surface temperature distribution in the frozen soil was established. Combined with the finite element numerical calculation of the unsteady heat conduction model, Model are combined to further analyze and calculate the change of the geotemperature zone in the frozen soil after 50 years and 100 years.The results show that the permafrost can still remain at the current surface temperature of 1.5 ℃ and the temperature is increased by 0.048 ℃ a-1 At current temperatures of 0.5 ℃ and -0.5 ℃, the permafrost may still exist in each of 50 years and 100 years. The permafrost area will be reduced from the current 2.57 × 105 km2 to 1.84 × 105 and 1.29 × 105, respectively km2, a decrease of 28.4% and 49.8% respectively, with a greater magnitude of degradation in the east than in the west At the same time, the regional geothermal temperature increases and the permafrost thickness decreases. The area of stable type (annual mean ground temperature Tcp≤-1.0 ℃) decreases gradually from 1.07 × 105 km2 to 8.8 × 104 km2 Year) and 5.6 × 104 km2 (after 100 years), correspondingly, the area of the unstable (Tcp> -1.0 ℃) permafrost and seasonal permafrost increases and the southern boundary of the frozen soil will significantly move northward. Will have a significant impact on the engineering facilities and ecological environment in the cold area of Northeast China.It is feasible to reduce or avoid artificially changing the conditions of permafrost so as to protect the environment of permafrost.