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    基于GF-2卫星数据的孕穗期小麦叶面积指数反演——以河北省廊坊市为例

    Estimating leaf area index of wheat at the booting stage using GF-2 data:A case study of Langfang City,Hebei Province

    • 摘要: 叶面积指数(leaf area index,LAI)是评价植被长势和预测产量的重要农业生理生态参数.高分2号(GF-2)卫星数据具有高空间分辨率特点,能反映更多细节信息,针对该数据特点的LAI反演方法具有较高的研究价值.以河北省廊坊市万庄镇为研究区,对孕穗期小麦采用了回归模型和神经网络算法反演LAI;采用4种植被指数与实测LAI值构建回归模型,同时重点探讨了PROSAIL模型结合神经网络方法进行LAI反演.研究结果表明,在回归模型中,归一化植被指数(normalized difference vegetation index,NDVI)的二项式模型估算LAI可以获得最高精度,采用实测数据验证的决定系数(R2)和均方根误差(root mean square error,RMSE)分别为0.7193和0.3936;与回归模型相比,神经网络反演LAI方法更显著提高了精度,R2和RMSE分别达到0.9008和0.2732.基于GF-2卫星数据,在研究区小麦孕穗期,神经网络反演LAI具有较强可行性和适用性,可为高空间分辨率卫星影像的LAI反演提供参考.

       

      Abstract: Leaf area index(LAI) is an important agricultural parameter to assess crop growing status for production estimation. Due to its very high spatial resolution,GF-2 can be used as a new source of remote sensing data for crop monitoring. It is particularly valuable to develop approaches for LAI estimation using GF -2 data. In this paper, the study of LAI estimation for wheat at the booting stage in Wanzhuang Town, Langfang City of Hebei Province in North China Plain is presented. Canopy LAI of wheat at the booting stage was measured over an experimental field in the town. Regression analysis method was performed with LAI and four different vegetation indexes,and the neural network method combined with the PROSAIL model was also considered. The results show that the best LAI retrieval regression model is the binomial model of normalized difference vegetation index (NDVI). The correlation coefficient (R2) and root mean square error (RMSE) are 0. 719 3 and 0. 393 6 respectively. Compared with the regression analysis method, the accuracy is greatly improved by using neural network method,and the R2and RMSE reached 0.900 8 and 0.273 2 respectively. Neural network method has feasibility and applicability based GF-2 data at wheat booting stage,which would provide a reference scheme for LAI inversion from high spatial resolution satellite image.

       

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