蒸散发遥感反演产品应用关键问题浅议  

Critical Problems When Applying Remotely Sensed Evapotranspiration Products

作　　者：熊育久 冯房观 方奕舟 邱国玉 赵少华 姚云军 Xiong Yujiu;Feng Fangguan;Fang Yizhou;Qiu Guoyu;Zhao Shaohua;Yao Yunjun(School of Civil Engineering,Sun Yat-Sen University,Guangzhou 510275,China;Guangdong Engineering Technology Research Center of Water Security Regulation and Control for Southern China,Guangzhou 510275,China;Satellite Environment Center,Ministry of Ecology and Environment/State Environmental Protection Key Laboratory of Satellite Remote Sensing,Beijing 100094,China;Faculty of Geographical Science,Beijing Normal University,Beijing 100875,China;不详)

机构地区：[1]中山大学土木工程学院,广东广州510275 [2]广东省华南地区水安全调控工程技术研究中心,广东广州510275 [3]北京大学深圳研究生院环境与能源学院,广东深圳518055 [4]生态环境保护部卫星环境应用中心/国家环境保护卫星遥感重点实验室,北京100094 [5]北京师范大学地理科学学部,北京100875

出　　处：《遥感技术与应用》2021年第1期121-131,共11页Remote Sensing Technology and Application

基　　金：国家自然科学基金面上项目“黄土高原蒸散发组分时空格局及其对植被恢复的响应研究”(42071395);“干旱区绿洲与荒漠植被蒸散发及其组分定量遥感反演研究”(41671416)。

摘　　要：陆地蒸散发精确测算是地球系统和全球变化研究的薄弱环节与难点。遥感提供的蒸散发产品极大地推动了相关领域的研究,但蒸散发遥感产品种类多、反演理论涉及水文学与遥感科学,不仅影响初涉该领域的用户选择产品,且无视数据物理含义、简单拿来主义式的应用可能导致不合理的分析结果,影响科学问题深入研究。基于MODIS、GLEAM等6种长时间序列(1980~2018年)蒸散发遥感产品,以黄土高原蒸散发多年变化趋势为应用案例,从产品特征、反演算法与精度等角度,探讨在应用蒸散发遥感产品时需要注意的关键问题。结果表明:(1)各种蒸散发产品与观测值在年尺度上差异显著(方差分析/ANOVA,P<0.01)、相对误差在17%~30%之间(R~2<0.4);(2)蒸散发多年平均值的空间分布整体趋势相似、但局部差异明显(同一区域可高达400 mm/y);(3)产品差异使得统计的黄土高原蒸散发变化趋势不一致,甚至出现相反的变化趋势。可见,应用蒸散发遥感产品前,需查明产品算法、输入数据特征、产品反演精度(如误差大小及来源),掌握产品的优点与局限性;有可供利用的观测数据时,务必深入检验产品在拟开展研究区域的精度,方能根据产品提供的数据展开客观分析。研究结果可为干旱、半干旱地区蒸散发产品选择与应用提供参考。Accurate estimation of terrestrial evapotranspiration(ET)is challenged substantially in studies on the Earth system and global change.Remotely sensed ET products have greatly fostered researches on related areas.However,there are various ET products retrieved based on different theories involving hydrology and quantitative Remote Sensing(RS).These theories are probably too esoteric to understand for students and young scientists(new users)alike.As such,ignoring the physical meaning of the products may hinder their proper application,lead to unreasonable analysis and affect an in-depth study of scientific problems.Therefore,we compared and analyzed six RS-based ET products,including MODIS and GLEAM(1980~2018),over the Loess Plateau,northwest China,aiming to discuss critical problems when applying these products.The results show that:(1)there is a low correlation between RS-based ET and water balance ET(R~2<0.4)because significant differences exist at yearly scale(ANOVA,P<0.01),with mean absolute percent errors ranging from 17%to30%;(2)spatially,although ET values show a similar distribution in general,substantial difference exists at certain regions,with a value up to 400 mm/y;(3)when analyzing change trends of ET over the Loess Plateau based on these ET products,inconsistent trend or even opposite change trends will be observed.It concluded that before applying RS products,one should perform validations and master their advantages and limitations before application,including algorithm,model input and possible error propagation.This study can provide guidelines for selecting proper ET products for related researches in arid and semi-arid regions.

关 键 词：蒸散发 遥感反演 全球产品 黄土高原 

分 类 号：P237[天文地球—摄影测量与遥感] TP75[天文地球—测绘科学与技术]