集成热红外和微波遥感的农田蒸散估算方法研究

Considering the difficulty of highly efficient,all-weather and all-time farmland evapotranspiration (ET) estimation using single visible, near infrared, thermal infrared or microwave remote sensing data, this proposal has been put forward based on the theory of the soil -crop energy budget, the mechanism of electromagnetic radiation transmission and microwave scattering, to analyze the quantitative relationship of the soil resistance, crop canopy resistance and electromagnetic waves, using Penman-Monteith ET model, thermal infrared and microwave remote sensing. This project will illustrate the mechanism between farmland ET and electromagnetic waves, and further to develop all-weather farmland ET estimation method using remotely sensed data. Meantime, a series of validation for this model has been carried out using farmland flux observation data (Guantao, Daxing, etc.) over northern China, and further amended to improve ET algorithm to improve the simulation accuracy to provide technical support for water resources management and surface drought monitoring.

针对单独采用可见光、近红外、热红外或微波波段很难实现对农田蒸散高时效、全天候和全天时综合估算这一科学问题。本课题从土壤-作物能量平衡理论角度入手，以电磁波辐射传输机制以及地物微波散射机制研究为主线，利用Penman-Monteith蒸散模型，从热红外和微波遥感两个层面分别探索土壤阻抗以及作物冠层阻抗与电磁波的定量关系，阐明农田蒸散与电磁波作用机理，集成热红外和微波遥感信息，构建全天候的农田蒸散综合遥感估算方法。同时，利用中国北方农田通量观测站点（馆陶、大兴等）数据，开展一系列遥感蒸散模型的验证工作，并进一步修正与改进蒸散算法，提高模拟效果，为国家水资源管理和地表干旱监测提供技术支持。

根据项目研究目标，利用MODIS遥感数据、AMSR-E微波遥感土壤水分产品以及再分析气象资料，提出了混合型蒸散遥感估算方法（Hybrid-PT）、基于表观热惯量和植被指数的Priestley-Taylor算法（MS-PT）以及基于贝叶斯模型平均值方法的陆表蒸散估算方法（BMA），经过国内Chinaflux以及全球Fluxnet地面涡度相关观测数据验证表明：Hybrid-PT算法考虑了微波土壤水分具有较高的模拟精度，MS-PT具有较高的可操行性和物理基础，而BMA精度最高，可用于全球产品生产。最后，这些方法在中国北方陆表水循环参量估算中得到较好的示范应用。