基于野外观测和TM数据的锡林浩特典型草原MODIS/LAI产品验证

草业学报 ›› 2011, Vol. 20 ›› Issue (4): 252-260.

基于野外观测和TM数据的锡林浩特典型草原MODIS/LAI产品验证

王圆圆¹,王猛^2,3,李贵才^1*,王军邦²,杨忠东¹,戎志国¹

1.中国气象局中国遥感卫星辐射测量和定标重点开放实验室国家卫星气象中心,北京 100081;
2.中国科学院地理科学与资源研究所,北京100101;
3.中国科学院研究生院,北京 100049

收稿日期:2010-06-11 出版日期:2011-04-25 发布日期:2011-08-20
通讯作者: E-mail:ligc@cma.gov.cn
作者简介:王圆圆(1981-),女,安徽六安人,助研,博士。E-mail:wangyuany@cma.gov.cn
基金资助:
公益性行业科研专项[GYHY(QX)2007-6-9,GYHY200906036]和国家自然科学基金(40501048)资助。

Research on validating MODIS/LAI product in a typical semi-arid steppe of Xilinhot in Northern China

WANG Yuan-yuan¹, WANG Meng^2,3, LI Gui-cai¹, WANG Jun-bang², YANG Zhong-dong¹, RONG Zhi-guo¹

1.Key Lab of Radiometric Calibration and Validation for Environmental Satellites, China Meteorological Administration (LRCVES/CMA), National Satellite Meteorological Center, Beijing 100081, China;
2.Institute of Geographic Sciences and Natural Resources, CAS, Beijing 100101, China;
3.Graduate School of Chinese Academy of Sciences, Beijing 100049, China

Received:2010-06-11 Online:2011-04-25 Published:2011-08-20

摘要/Abstract

摘要： 通过2008年夏季生长季的3期LAI野外观测和TM图像的处理分析,对锡林浩特国家观象台附近24 km²典型草原区的MODIS/LAI产品精度从时空2种维度进行了评估。结果显示,在时间维度上,MODIS/LAI产品可以较为准确的体现草地植被生长轨迹;在空间维度上,MODIS/LAI产品与TM/LAI反演结果有相似的变化趋势。以TM/LAI结果为参考真值,MODIS/LAI产品的相对均方根误差约为24%,并存在10.8%的正偏差,表明有一定程度的高估。误差分析结果显示,MODIS/LAI产品精度主要受到土壤背景光谱以及地表均匀程度的影响,在LAI较小的区域,以及在草地空间异质性因受人类活动而增强的7月初和8月末,MODIS/LAI产品误差更大。

Abstract: MODIS/LAI product in a typical semi-arid steppe of Xilinhot in Northern China was validated based on three comprehensive field surveys which were carried out during July-August 2008 in the study area. LAI was measured in 25 m×25 m plots by a destructive harvest method of 80 intensive plots and 20 scattered plots. Three TM/ETM+ images acquired during the field survey periods were collected and processed. The validation work covered two parts: Time series analysis and spatial pattern analysis. In time series analysis, MODIS/LAI track in the intensive sampling region extracted from DOY169 to DOY241 were compared with ground measured values. In spatial pattern analysis, LAI map with 30 m spatial resolution were first derived by building a regression line between LAI and TM band 5 (1.6 μm), and then aggregated to 1 km spatial resolution based on MODIS grids. Results indicated that in the temporal domain MODIS/LAI product can correctly reflect grass growth trends; In the spatial domain it showed a similar pattern with TM/LAI (1 km). Using the TM/LAI as reference, the relative RMSE of MODIS/LAI was about 24% and a positive bias (10.8%) existed, suggesting slight over-estimation. Error distribution analysis revealed that the MODIS/LAI product was less accurate in regions with lower LAI values, probably due to soil contamination. Moreover, the relative RMSE of the MODIS/LAI product was higher at the beginning of July and the end of August when the heterogeneity of grass cover increased as a result of human activities.

中图分类号:

S812.3

王圆圆,王猛,李贵才,王军邦,杨忠东,戎志国. 基于野外观测和TM数据的锡林浩特典型草原MODIS/LAI产品验证[J]. 草业学报, 2011, 20(4): 252-260.

WANG Yuan-yuan, WANG Meng, LI Gui-cai, WANG Jun-bang, YANG Zhong-dong, RONG Zhi-guo. Research on validating MODIS/LAI product in a typical semi-arid steppe of Xilinhot in Northern China[J]. Acta Prataculturae Sinica, 2011, 20(4): 252-260.

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