Simulation of CO_2 and Sensible/Latent Heat Fluxes Exchange between Land Surface and Atmosphere over Cropland and Grassland in Semi-Arid Region
Simulation of CO_2 and Sensible/Latent Heat Fluxes Exchange between Land Surface and Atmosphere over Cropland and Grassland in Semi-Arid Region
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发表时间：
2006
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通讯作者：
J. Ji;Yan Xiao;H. Yao;Guo Wei;Liu Hui;Wang Shu;S. Regional
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作者：
J. Ji;Yan Xiao;H. Yao;Guo Wei;Liu Hui;Wang Shu;S. Regional
综合生物圈模拟器（IBIS）是基于动态植被方案模拟陆地生物圈过程的最成熟的模型之一。为了验证IBIS在半干旱地区的有效性，最终提高模型对我国特定土地覆盖类型的能力，在吉林省通榆野外观测站（44°25′N，122°52′E）对2003年全年耕地和退化草地进行了模拟。中国是国际协调增强观测周期(CEOP)的参考站点之一。模型输入包括站点生态系统特征和主要气象变量。模拟地表通量与涡度协方差(EC)观测结果的比较表明,该模型能够再现CO_(2)、感热通量和潜热通量,相关系数超过0.05的显着性水平。总体而言,CO_(2)通量和感热通量具有明显的相关性。草地和农田均存在日变化和季节变化,而与蒸散相关的潜热通量仅在生长季有日变化。同时,农田的通量均大于退化草地,特别是在生长季,其可能的原因之一是作物生长状况比退化草地好。该模型普遍估算年CO_(2)较低(低估了草地9.29%)耕地的模拟值比EC测量值高出3.73%），潜热通量（对应百分比为4.63%和3.48%）和年感热通量（分别高估了9.90%和11.98%）均高于EC实测值，且对耕地的模拟效果优于对草地的模拟，模型与实测的一致性更为合理。
The Integrated Biosphere Simulator(IBIS) is one of the most sophisticated models in simulating terrestrial biosphere processes based on dynamic vegetation schemes.For the purpose of validating IBIS in semi-arid region and eventually improving the model's capability for specific land cover types in China,a simulation for the whole 2003 year was conducted over cropland and degraded grassland in Tongyu field observation station(44°25′N,122°52′E) in Jilin Province of China,which is one of the reference sites of international Coordinated Enhanced Observing Period(CEOP).Model inputs include the site ecosystem characteristics and main meteorological variables.Comparisons between simulated land surface fluxes and observed eddy covariance(EC) measurements show that the model is capable of reproducing CO_(2),sensible and latent heat fluxes indicated by correlation coefficients exceeding the significant level of 0.05.In general,CO_(2) flux and sensible heat flux have obvious diurnal and seasonal variation both at the grassland and the cropland,while the latent heat flux,which is related to evapotranspiration,only has diurnal variation during the growing season.Meanwhile,all fluxes at the cropland are larger than those at the degraded grassland,especially in the growing season,and one of possible reasons for these is that crops grow much better than degraded grass.The model generally estimates lower annual CO_(2)(underestimating 9.29% in the grassland and 3.73% in the cropland) and latent heat flux(with corresponding percents 4.63% and 3.48%),and greater annual sensible heat flux(overestimating 9.90% and 11.98%,respectively) than measured by EC.And the simulations for the cropland are better than those for the grassland,with more reasonable model-measurement agreements.