doi:  10.3878/j.issn.1006-9895.1810.17181
黄河源区高寒湿地冻结过程中土壤热通量变化特征分析

Analysis on the characteristics of soil heat flux in the freezing process of alpine wetland in source area of the Yellow River
摘要点击 155  全文点击 61  投稿时间:2017-06-20  修订日期:2018-10-15
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基金:  国家自然科学基金项目
中文关键词:  高寒湿地  冻融过程  土壤热通量  冻结潜热
英文关键词:  alpine wetland  freezing process  l heat flux  freezing latent heat
                 
作者中文名作者英文名单位
李光伟Li Guangwei中国科学院西北生态环境与资源研究院
文军Wen Jun中国科学院西北生态环境与资源研究院
王欣中国科学院西北生态环境与资源研究院
王作亮中国科学院西北生态环境与资源研究院
贾东于中国科学院西北生态环境与资源研究院
陈金雷中国科学院西北生态环境与资源研究院
引用:李光伟,文军,王欣,王作亮,贾东于,陈金雷.2019.黄河源区高寒湿地冻结过程中土壤热通量变化特征分析[J].大气科学
Citation:Li Guangwei,Wen Jun.2019.Analysis on the characteristics of soil heat flux in the freezing process of alpine wetland in source area of the Yellow River[J].Chinese Journal of Atmospheric Sciences (in Chinese)
中文摘要:
      准确量化高寒湿地下垫面冻结过程中土壤热通量的变化特征,对认识高寒湿地-大气间水热交换过程有重要的科学意义。本文利用中国科学院麻多气候与环境综合观测站2014年5月至2015年5月的观测资料,分析了下垫面冻结过程中土壤热通量变化特征,探讨了冻结潜热对土壤热通量的贡献。基于温度积分计算土壤热通量的算法,指出在计算冻结过程中的土壤热通量时,需要同时考虑土壤热通量板以上的土壤热贮存及热通量板以上的冻结潜热。研究表明:(1)冻结锋面形成后,锋面所在深度土壤体积含水量迅速降低,锋面以下土壤热通量接近于零,土壤液态水开始冻结,冻结潜热向上穿过热通量板所在土壤层;降水下渗土壤后冻结所释放的潜热能使次日凌晨5cm深度土壤热通量接近于零。(2)季节性冻结期,凌晨气温较高时穿过5cm土壤层的向上土壤热通量很小,可能是由表层土壤发生了日冻融循环所致。土壤水释放的冻结潜热使土壤温度波动减弱并维持在冰点附近。高寒湿地下垫面仅在很浅的表层发生日冻融循环,无法通过5cm土壤温度资料判断下垫面循环出现日期。(3)加入冻结潜热项,土壤热通量的计算值与实测值之间的均方根误差将会从11.5 W?m-2下降到6.2 W?m-2。以上研究结果对认识寒区陆面过程有重要的贡献。
Abstract:
      The accurate quantification of soil heat flux in the freezing process of alpine wetland in source area of the Yellow River has an important scientific significance for understanding the water and heat exchanges between alpine wetlands and the atmosphere. By using the field observed data collected at the Maduo Climate and Environment Comprehensive observatory of Chinese Academy of Sciences from 2014 to 2015, the characteristics of soil heat flux when the alpine wetlands are freezing were analyzed, and the effect of latent heat of fusion on soil heat flux was discussed. When calculate the soil heat flux at alpine wetland by using the simple measurement approach algorithm, both heat storage and latent heat of fusion loss from above the plate must be taken into account. Large errors can be found if latent heat of fusion is ignored. The main results are as follows: (1) After the freezing front appeared, soil heat flux which at a depth below the freezing front will decrease and near to zero, the liquid water content of soil at the depth of the freezing front will decrease rapidly, the soil below the freezing front begins to freeze, and the freezing released latent heat travels upward through the soil layer where the soil heat flux plate is located and be observed. Precipitation infiltrate into the soil and released the freezing latent heat, and the freezing latent heat caused the observed soil heat flux near to zero at 5cm depth. (2) During the seasonally freezing processes, upward soil heat flux at depth of 5cm is near to zero if there is high temperature in the morning and in the yesterday noon, this phenomenon indicated that there are diurnal freezing-thawing cycle exist. Latent heat released by soil water can reduce the amplitude of soil temperature and keep the soil temperature near at freezing point. The diurnal freezing-thawing processes solely occur in a very shallow soil layer, makes it difficult to ascertain whether diurnal freezing-thawing cycle is happened or not just by using soil temperature data at 5cm depth. (3) Ignoring latent heat of fusion process will increase the root mean square errors of soil heat flux between the observed and calculated values from 6.2W/m2 to 11.5 W/m2. All these findings have contributions of comprehension land surface processes in cold regions.
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