黄土高原农田种植结构的改变对陆面能量和水分交换、 区域蒸散发等产生影响， 不同作物下垫面复杂的水热耦合机制在黄土高原陆-气相互作用中起着重要作用。本文利用陇东黄土高原2019 -2021年共计34个月的观测数据， 结合耦合了作物模块的通用陆面模式（Community Land Model with BGC Biogeochemistry and prognostic crop， CLM5.0-BGCCROP）对黄土高原不同作物下垫面（冬小麦、 玉米、 苹果林地）的陆面特征进行离线单点模拟， 以验证CLM5.0陆面过程模式在黄土高原农田地区的模拟能力， 对比分析不同作物下垫面土壤温湿度和地表能量通量的差异。结果表明： （1）CLM5.0对土壤温湿度特征的模拟效果较好， 平均均方根误差分别小于2.5 ℃和0.1 m³·m^-3， 小麦地土壤温度模拟值偏高， 玉米地和苹果林地土壤温度模拟存在冷偏差。生长期在旱期的冬小麦造成土壤干燥的程度大于玉米， 苹果林地因根系丰富， 吸收了更多的土壤水， 使土壤整体更加干燥。（2）模拟偏差一部分是由于在模式中将作物下垫面设置为单一作物类型（冬小麦、 玉米和苹果林地）时， 高估（低估）了（非）生长期作物的叶面积指数， 低估（高估）了地表反照率， 高估（低估）了净辐射通量， 更多（少）的能量转化为感热潜热。（3）另一部分偏差来自于农田不同的作物管理方式， 如实际上作物收割后并不完全翻耕为裸土， 模式高估了小麦地和玉米地收割后的土壤温度和土壤液态水含量； 模式中没有地膜覆盖选项， 导致玉米地土壤温度、 土壤液态水含量模拟偏低， 模拟平均偏差约-1.84 ℃和-0.058 m³·m^-3。（4）冬小麦-玉米混合下垫面模拟试验能较好地模拟地表能量通量， 净辐射、 感热通量、 潜热通量的模拟平均偏差分别为-6.13 W·m^-2、 11.46 W·m^-2、 -1.97 W·m^-2。在生长期内， 冠层蒸腾作用占主导， 随着作物叶面积指数的增加， 感热通量减少， 土壤温度降低， 潜热通量增加， 土壤液态水含量减少。

Changes in the planting structure of farmland on the Loess Plateau impact land surface energy and water exchange， regional evapotranspiration， etc.The complex hydrothermal coupling mechanism of different crop underlying surfaces plays an essential role in the land-atmosphere interaction on the Loess Plateau.In this paper， based on the observation data of 34 months from 2019 to 2021 in the east of Gansu province， combined with CLM5.0-BGCCROP coupled with the crop module， the land surface characteristics of different typical crops （winter wheat， corn， and apple forest） on the Loess Plateau were offline single-point simulated.To verify the simulation ability of CLM5.0 on the land surface processes of agricultural fields on the Loess Plateau and compare the differences in soil temperature， soil liquid water content， and surface energy fluxes of different crops.The results showed that： （1） CLM5.0 has a better simulation effect on soil temperature and liquid water content characteristics， average RMSE is less than 2.5 \text{?} ℃ and 0.1 m³·m^-3， respectively.The simulated soil temperature values in the wheat field are high， and there is a cold bias in the corn and apple fields.Winter wheat， which has a dry growth period， caused more soil drying than corn.Apple forest， which has a rich root system， absorbed more soil water， making the soil drier overall.（2） Part of the simulation bias is due to setting crop underlying surfaces to a single crop functional type in the model， overestimating the leaf area index of crops during the growth period， underestimating the surface albedo， overestimating the net radiation flux， and converting more energy flux into sensible and latent heat flux.（3） Another part of the simulation bias comes from the diverse crop management methods in the farmland.For example， crop fields are not completely tilled to bare soil after harvest， and the model overestimates soil temperature and soil liquid water content in wheat and corn fields.The model does not have the mulching option， which leads to the low simulated soil temperature and soil liquid water content in corn fields， about 1.84 \text{?} ℃ and 0.058 m³·m^-3， respectively.（4） The winter wheat and corn mixed crop underlying surface simulation experiment could better simulate the surface energy fluxes， and the simulated average deviations of net radiation， sensible heat flux， and latent heat flux were -6.13 W·m^-2， 11.46 W·m^-2， -1.97 W·m^-2， respectively.During the growth period， canopy transpiration dominates， and with the increase of crop leaf area index， sensible heat flux decreases， soil temperature decreases， latent heat flux increases， and soil liquid water content decreases.