应用Penman-Monteith模型估算稻田蒸散的误差分析

Error Analysis on Evapotranspiration Estimation of Paddy Rice Field by Penman Monteith Model

通过对Penman-Monteith模型（PM模型）进行微分处理,从理论上分析了土壤热通量、储热项、表面层阻力和空气动力学阻力对PM模型模拟稻田蒸散的误差贡献;在此基础上提出储热项修正和稳定度修正建议,并对水稻4个生育期修正后的PM模拟结果与原始模型模拟结果进行比较.分析表明：按照一般量级关系,净辐射、土壤热通量、储热项、表面层阻力、空气动力学阻力误差分别为5％、10％、100％、20％和20％时,对蒸散误差的贡献率分别为26.8％、5.36％、53.6％、11.11％、3.17％.在水稻移栽-拔节、拔节-抽穗、抽穗-灌浆、成熟4个生育期,10cm土层的储热量均大于田间水层的储热量,且土层和水层储热量均随生育期推进而降低.水层储热在前两个生育期对蒸散的影响比后两个生育期大,与原始模拟值相比,前两个生育期仅考虑土壤储热修正后7：00-14：00蒸散降低幅度为0.04～ 0.073、0.02 ～0.11mm ·h-1,仅考虑水层储热修正后蒸散降低幅度为0.006～0.038、0.003～0.015mm·h-1;仅考虑空气动力学阻力修正后4个生育期的蒸散值平均降低了0.00064、0.0134、0.0055、0.0024mm·h-1.

Based on the features of the paddy rice field environment and Penman-Monteith model, the error contribution of soil heat flux, storage heat term, surface resistance and aerodynamic resistance to the estimation of evapotranspiration were analyzed theoretically by differential error method. Then the modified Penman-Monteith model was obtained with considering soil and water heat storage, atmospheric stability correction, and its simulated values were compared with those of the original model. The results showed that in accuracy of 5% net radiation, 10% soil heat flux, 100% heat storage,20% surface resistance and 20% aerodynamic resistance led to 26.8% ,5.36% ,53.6 %, 11.11% and 3.17% the error of evapotranspiration estimation according to normal ordering relationships, respectively. Heat storage of 10cm depth soil layer and water layer of paddy rice field decreased with the development of 4 growing stages including transplanting-jointing stage, jointing-tasseling stage, tasseling-filling stage and maturing stage. The effects of heat storage of water layer on the estimation of evapotrhnspiratin in the former 2 stages were greater than that of latter 2 stages. Compared with the values simulated by original model, the evapotranspiration simulated values improved 0. 04 - 0. 073,0.02 -0. llmm .h-I only with soil heat storage correction and 0. 006 - 0. 038,0. 003 - 0. 015mm·h -1 only with water heat storage correction during 7：00 -14：00. Only through aerodynamic resistance correction ,the simulating error decreased 0. 00064,0. 0134,0. 0055,0. 0024mm· h -1 on average during 4 growing stages. The results couldprovide scientific reference so as to improve the accuracy of simulating paddy field evapotranspiration.