三温模型和基于阻抗蒸散发模型的整合与模拟分析

Integration and simulation analysis of temperature gradient based 3T and resistance-based evapotranspiration model

【目的】整合消除阻抗的三温模型和基于阻抗的双源模型,开展蒸散发(ET)和蒸腾(T)的模拟及对比分析,实现不同模型的融合与蒸散发的动态模拟。【方法】本研究基于已有的双源阻抗模型框架、干土壤和干叶片能量平衡,结合数值模拟技术模拟了参考温度的季节动态,并将其与三温模型整合开展蒸腾和土壤蒸发的模拟。【结果】与涡动实测值相比,三温模型和双源模型对大满站日尺度ET模拟,R^(2)分别为0.85和0.72,对温带草地站小时尺度ET模拟,R^(2)均为0.89。在小时尺度模拟效果更好。并且,三温模型和双源模型对植被蒸腾的估算结果较为一致(R^(2)分别为0.67、0.68)。以上研究表明该研究框架对三温模型中参考温度的估算,提供了理论方法支撑,较好地量化了参考温度的时空动态。(2)模型情景试验分析表明:两个模型对2个站点的ET和T的预测结果相似,前提是冠层可利用能量(如净辐射)和地面土壤可利用能量(如净辐射和地热通量)受到能量平衡的限制。相反,由于输入驱动因子(温度和辐射)在干湿情景下的系统不匹配,三温模型对T和ET的模拟精度显著下降。因此,在能量平衡的框架内,干湿土地条件下输入的温度和辐射系统匹配时,三温模型的效果更好。(3)参考温度具有一定的日变化与季节变动。【结论】在白天,叶片和土壤参考温度普遍高于实际温度,而在夜晚低于实际温度,呈现出较大的日变幅。就日均值而言,参考温度普遍高于实际模拟温度。本研究的结果提供了一种新的温度梯度计算方法,可用来监测冠层水分胁迫及动态。

[Objective]This paper integrates the three temperature model that eliminates impedance and impedance based dual source model to simulate and compare evapotranspiration(ET)and transpiration(T),achieving the fusion of different models and dynamic simulation of evapotranspiration.[Method]Based on the existing two-source impedance model framework and the energy balance of dry soil and dry leaves,combined with numerical simulation technology,this study simulated the seasonal dynamics of reference temperature,and integrated it with the three-temperature model to simulate transpiration and soil evaporation.[Result](1)Compared with the eddy measured ET,the R^(2)of ET estimated by the threetemperature model and the two-source model for the observations at Daman Station at the daily scale were 0.85 and 0.72,respectively,and R^(2)of the simulated temperate grassland station at the hourly scale was 0.89,and the simulation effect was better at the hourly scale.The above research showed that the research framework provided theoretical support for the estimation of reference temperature in the three-temperature model,and better quantified the spatio-temporal dynamics of reference temperature.(2)Model scenario test analysis showed that the prediction results of T and ET of the two models were similar,provided that canopy available energy(such as net radiation)and ground soil available energy(such as net radiation and surface heat flux)were limited within the framework of energy balance.On the contrary,due to the mismatch of the input driving factors(temperature and radiation)in the dry and wet scenarios,the simulation accuracy of T and ET by the“three-temperature”model decreased significantly.Therefore,in the framework of energy balance,the effect of three-temperature model was better when the input temperature and radiation system match under dry and wet land conditions.(3)The reference temperature had certain diurnal and seasonal variations.[Conclusion]In the daytime,the leaf or soil reference temperature is generally higher than the actual temperature,but lower than the actual temperature at night,showing a large daily variation.In terms of daily mean,the reference temperature is generally higher than the actual simulated temperature.The results of this study provide a promising new temperature gradient method and can be used to monitor canopy water stress and dynamics.