ETWatch中的参数标定方法

ETWatch:calibration methods

ETWatch是用于流域蒸散遥感监测、针对遥感应用而设计的集成框架。方法集成了具有不同应用优势的遥感蒸散模型,并以Penman-Monteith方法为基础建立时间扩展方法,利用气象数据与晴好日的通量遥感估算结果,获得逐日连续的蒸散分布图。所生成的从流域级到地块级的数据产品能动态反映区域蒸散发的时空变化规律。为深入了解遥感蒸散量估算中的不确定因素,本文将其通量计算过程分为地表温度、地气温差、短波与长波辐射、水体热通量、显热通量等环节与地面数据进行对比和逐项的标定。利用站点地面观测资料对模型输入的蒸发比的比较表明参数标定可有效提高遥感与地面蒸散观测的吻合程度。

Satellite imagery provides an unprecedented spatial distribution of critical land surface parameters.Numerous physical and empirical remote sensing-based models,in conjunction with ancillary surface and atmospheric data,have been developed to estimate evapotranspiration（ET） in the quantitative thermal remote sensing field.ETWatch is an operational scheme for watershed ET monitoring,which is designed to integrate with various types of remote-sensed ET models to obtain continuous ET maps.To reduce the errors from modeling,we improved ETWatch to carry out calibration on key variables such as surface temperature,ground temperature difference,short-wave and long-wave radiation,water heat flux,and sensible heat flux,using ground measurement data.The validation results show that the calibration greatly improved the accuracy of ET products,and the importance of calibration cannot be overemphasized in applications used in watershed water management.