地形校正对叶面积指数遥感估算的影响

Effect of Topographic Correction on the Estimation of Leaf Area Index Based on Landsat TM

利用经过6S模型大气校正的地面反射率图像、数字地面高程数据以及改进的CIVCO地形校正模型,分别计算了褒河流域不同植被类型(阔叶林、针叶林和灌木林)的3类光谱植被指数(NDVI、SR和SAVI),并建立了各个植被类型叶面积指数与同时相的各个植被指数的相关关系。结果表明,地形校正能有效地消除大部分的地形影响,显著地提高各植被指数与叶面积指数的相关关系;对于阴坡和阳坡来讲,阴坡较阳坡提高显著;对于不同的植被类型,针叶林和灌木较阔叶林提高较为显著;对于同一植被指数如SAVI,灌木提高较针叶林和阔叶林显著,说明地形校正对叶面积指数的遥感估算结果有很大的影响。因此在利用遥感数据定量估算叶面积指数时,尤其对于山区,不仅要进行地形校正,而且要针对不同的植被类型选择合适的植被指数进行估算。

To analyze the effect of topographic correction on the relationship between vegetation indices（VI） and leaf area index（LAI）,the atmosphere corrected reflectance image obtained through 6S model,the digital elevation model（DEM） and topographic correction model of CIVCO were used.The normalizes difference vegetation index（NDVI）,simple ratio（SR） and soil adjusted vegetation index（SAVI） of different land cover including broad-leaved forests,coniferous forests and shrubs in Baohe basin were estimated,and the relationships between the VI（without topographic correction and with topographic correction） and the ground-based measurement of LAI were calculated.The results showed that the topographic correction significantly increased the correlation coefficients between LAI and VI.Compared with sunny slope,the correlation coefficients between LAI and VI on shade slope were significantly increased.The correlation coefficients between LAI and VI of coniferous forests and shrubs were increased than that of broadleaved forests.To the same VI such as SAVI,the correlation coefficient between LAI and VI of shrubs was increased than those of broadleaved forests and coniferous forest.It was suggested that more attention should be paid to the topographic correction and choose appropriate VI when the remote sensing data were applied to the quantitative analyzing and information collecting in field,especially in the mountainous area.