文章基本信息

标题：ESTIMATING VEGETATION PARAMETERS OF CEREALS USING AN ASTER 1A IMAGE
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作者：N. Sánchez ; R. González ; J. Prado 等
期刊名称：ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences
印刷版ISSN：2194-9042
电子版ISSN：2194-9050
出版年度：2007
卷号：XXXVI-7/C50
出版社：Copernicus Publications
摘要：The purpose of the present study is the validation of the ASTER images through the indirect estimation of several parameters of dry crops cover. Since 1999 the Department of Geography of the University of Salamanca (Spain) has established a network named REMEDHUS in this area consisting of twenty three stations for the measurement of soil moisture over a large area of 1,300 km 2 characterized by different soil and land use types. The objective of this project is to develop an efficient monitoring system of climatic, edaphologic and biophysical parameters. Moreover, the climatic monitoring is carried out by a meteorological station that provides a daily dataset. In 2005, this database was completed with a field campaign to estimate biophysical parameters such as plant biomass, water content and height. The direct field measurement was done around the REMEDHUS stations in two campaigns in April 2005, the same date of the acquisition of an ASTER 1A image in the same area. The vegetation cover present in these plots is a dry crops shape (cereals), in the growing stage of its phenologic cycle. The image was orthorectified by a rigorous model. The radiometric treatment consisted of two level calibrations based on: 1) the ERSDAC (Earth Remote Sensing Data Analysis Center, provider of ASTER) algorithm implemented by a specific application with the coefficients, gain and offset, provided in the image file, and 2) conversion of these at satellite radiance values in at surface reflectance by means of a method developed by Pons and Solé Sugra.és (1994) for VNIR Landsat TM images, here adapted for ASTER. RVI (Ratio Vegetation Index) and NDVI (Normalized Difference Vegetation Index) were tested with the obtained reflectance values. Good correlations were obtained with both indices and the biophysical on the ground parameters (aerial biomass, water content and plant heights), in all cases correlation coefficient higher than 0.7. The results show that it is possible to infer a direct relationship between the plant parameters and the indices, taking into consideration two prior constrictions: the radiometric performance of the images into physical values and the use of the vegetation indices at the growing stage of the crops cycle, related to vegetative activity
关键词：ASTER; radiometric correction; vegetation indices; radiance; reflectance; biomass