参考作物蒸散模型的参数化研究及误差来源的定量化解析

Parameter optimization is one of the key issues to accurately estimate the reference crop evapotranspiration. Current researches primarily focus on the evaluation and optimization of the solar radiation model, with little attention to other factors. The error analysis of the reference crop evapotranspiration model is almost blank. Based on the Penman-Monteith equation recommended by the FAO, the applicability of the different solar radiation and net long wave radiation models in each climate zone of China was systematically assessed and the accuracy of pressure and vapor pressure estimation models recommended in the Penman-Monteith equation was verified. On this basis, the optimal parameterization schemes of reference evapotranspiration model for different climatic zones of China wereestablished. The mathematical relationship of estimated error between the reference evapotranspiration and the solar radiation, net long wave radiation, pressure and vapor pressure was theoretically established by sensitivity coefficients to quantify the error contribution of the different elements and define the error source. The effect of parameter optimization on the spatial and temporal distribution of the reference crop evapotranspiration over China was also analyzed. Based on the optimal parameterization scheme, the applicability of several simple reference crop evapotranspiration models in each climate zone was assessed. The achievements are expected to improve the reference crop evapotranspiration estimated accuracy of China and help to accurately estimate the crop water requirements and wet index and provide a scientific basis for theevaluation of dry and wet conditions and irrigation area rational decision-making.

参数优化是准确估算参考作物蒸散的关键问题之一。现有研究主要关注于太阳辐射模型的评估优化，对其他要素模型的关注甚少，误差来源的解析几乎空白。本项目基于FAO推荐的Penman-Monteith公式，系统评估太阳辐射和净长波辐射模型不同参数化方案在中国各气候区的适用性，并验证FAO推荐的气压和水汽压模型的准确性，在此基础上建立适用于不同气候区参考作物蒸散模型的最优参数化方案；借助敏感系数，从理论上建立参考作物蒸散估算误差与太阳辐射、净长波辐射、气压和水汽压估算误差的数学关系，定量解析不同要素估算误差对于参考作物蒸散估算误差的贡献，明确参考作物蒸散模型的误差来源；揭示参数优化对参考作物蒸散时空分布的影响；基于最优参数化方案，评估简化参考作物蒸散模型在各气候区的适用性。预期成果将改善中国参考作物蒸散的估算精度，有助于准确估算作物需水量和干湿指数，为区域干湿状况评价和灌溉决策合理制定提供科学依据。

参数优化是准确估算参考作物蒸散的关键问题之一。现有研究主要关注于太阳辐射模型的评估优化，对其他要素模型的关注甚少，误差来源的解析几乎空白。. 本项目基于FAO56推荐的Penman-Monteith公式，利用观测资料，分区建立了太阳辐射和净长波辐射估算模型新的参数化方案，并系统评估了不同参数化方案在中国的适用性，发现新方案的估算精度较国内外常用辐射估算参数化方案有明显提高；同时，验证了FAO56推荐的气压和水汽压模型的准确性，认为在中国基本适用，但资料能够获取时优先使用实测值；在以上工作基础上，建立了适用于中国11个气候区的参考作物蒸散模型的新参数化方案及相应的数据集，新参数化方案对参考作物蒸散的估算精度在国内外常用参数化方案中最优，较FAO56推荐的参数化方案提高了40%以上。借助敏感系数法，从理论上建立了参考作物蒸散估算误差与太阳辐射、净长波辐射、气压和水汽压4个关键要素估算误差的数学关系，定量评估了不同要素估算误差对于参考作物蒸散估算误差的贡献，明确了参考作物蒸散估算误差的主要来源是太阳辐射和净长波辐射估算误差，两者对参考作物蒸散估算误差的贡献较大，水汽压的贡献较小，气压的贡献可以忽略不计。分析了新参数化方案和 FAO56 推荐参数化方案下中国参考作物蒸散的时空分布特征，揭示了参数优化对参考作物蒸散时空分布的影响主要体现在：FAO56推荐参数化方案计算的参考作物蒸散估算值系统性偏大和时间变化趋势明显偏小。以新参数化方案为标准，评估了5种简化参考作物蒸散估算模型在中国不同气候区的适用性，给出了气象要素观测资料不完备时，11个气候分区参考作物蒸散估算的最优简化替代公式。. 项目已产出论文共8篇，包括2篇SCIE收录论文，2篇EI收录论文，3篇核心期刊论文和1篇全国会议论文。. 项目研究成果将改善中国参考作物蒸散的估算精度，有助于准确估算作物需水量和干湿指数，为区域干湿状况评价和灌溉决策合理制定提供科学依据。