考虑碳氮水过程的动态根系方案在陆面模式SSiB4中的应用及效果评估  

Applications and Evaluations of Dynamic Root Scheme with Carbon-Water-Nitrogen Interactions in Land Surface Model SSiB4

作　　者：张一帆 缪昕 郭维栋[1] ZHANG Yifan;MIAO Xin;GUO Weidong(School of Atmospheric Science,Nanjing University,Nanjing 210023,Jiangsu,China)

机构地区：[1]南京大学大气科学学院,江苏南京210023

出　　处：《高原气象》2020年第3期511-522,共12页Plateau Meteorology

基　　金：国家重点研发计划项目(2017YFA0603803);国家自然科学基金项目(41775075)。

摘　　要：根系是植被重要组成部分,根系的动态变化可以通过调节根系吸水量改变土壤湿度,进而影响土壤蒸发等物理过程及植被蒸腾、光合作用等生化过程,最终改变生态系统物质循环和水热循环。本研究考虑土壤水分胁迫及土壤养分(氮)胁迫,模拟根系碳量在不同土壤层中的动态分配过程,用根系碳量比例表征根系的动态变化。基于SSiB4模式在亚马逊地区BRSa3站点、中国江西千烟洲CN-Qia站点进行单点模拟试验,研究动态根系方案对土壤湿度及陆气通量模拟结果的影响。结果表明:根系动态分布使更多深层土壤水分被吸收利用,改善了浅层土壤湿度的模拟效果,进而提高二氧化碳通量、感热及潜热通量的模拟精度。其中,BRSa3站点和CN-Qia站点浅层土壤湿度日平均的观测值与模拟值的相关系数分别提高了0.02和0.04,二氧化碳通量的相关系数分别提高了0.76和0.13,均通过99%显著性水平检验;改进了BRSa3站点干旱季和CN-Qia站点夏季碳吸收能力,二氧化碳通量的绝对偏差的改进幅度分别为33%和106%,二氧化碳通量日平均的观测值与模拟值的相关系数,分别提高了0.17和0.26,均通过99%显著性水平检验。总体而言,模拟时间段内各变量都更接近观测值,土壤湿度和二氧化碳通量的改进效果比感热通量和潜热通量的改进效果更加显著,土壤湿度通过土壤物理作用对感热通量和潜热通量的间接影响方式可能是造成差别的原因。各变量在BRSa3站点的改善更明显一些,不同植被覆盖类型的根系深度与结构可能是造成结果差别的主要原因。Root system is an important part of vegetation.The dynamic changes of root system can change soil moisture by adjusting the amount of water absorbed from root system,and then affect the biophysical processes such as soil evaporation and the biochemical processes such as transpiration and photosynthesis of vegetation.Eventually,the material cycle and the hydrothermal cycle of the ecosystem are changed by the dynamic changes of root system accordingly.In this study,soil water stress and soil nutrient(nitrogen)stress were considered to simulate the dynamic distribution of root carbon in different soil layers,and the dynamic change of root system was characterized by the ratio of carbon content in root system.Based on SSiB4 model,the single-point simula‐tion experiment was carried out at BRSa3 site in Amazon region and CN-Qia site in Qianyanzhou,China to study the effects of dynamic root system scheme on the simulation of soil moisture and land-atmosphere flux.The results showed that the dynamic distribution of root enables more soil water to be absorbed,which improved the simulation effect of shallow soil moisture,and then improved the simulation accuracy of carbon dioxide flux,sensible heat flux and latent heat flux.At the BRSa3 and CN-Qia sites,the correlation coefficients be‐tween the observed and simulated daily mean values of soil moisture were increased by 0.02 and 0.04,respec‐tively,and the correlation coefficients of carbon dioxide were increased by 0.76 and 0.13,respectively,which all passed the 99%significance test.The simulation of carbon absorption capacity of BRSa3 site in dry season and CN-Qia site in summer has been improved,and the absolute deviation was improved by 33%,106%,re‐spectively.The correlation coefficients between observed and simulated daily mean carbon dioxide flux were in‐creased by 0.17 and 0.26,which passed the 99%significance test.In general,all the variables were closer to the observed values after considering the dynamic root system scheme during the simulated time,and th

关 键 词：动态根系方案 陆面模式 土壤湿度 地表水热通量 二氧化碳通量 

分 类 号：P461[天文地球—大气科学及气象学]