基于GPS-IR的归一化植被指数反演

Iversion of normalized difference vegetation index based on GPS-IR

针对利用GPS接收机在接收L波段信号时对周围植被水分含量较为敏感的特性,使用GPS反射信号的变化,进行测站归一化植被指数(NDVI)反演.利用2个GPS参考站近5年的连续观测数据计算的归一化微波反射指数(NMRI),构建了反演NDVI的一元线性模型.NMRI整体变化趋势与同时间段内中分辨率成像光谱仪(MODIS)NDVI趋势表现一致,其反演结果相关系数R分别为0.62653、0.62573,均方根误差(RMSE)分别为0.05129和0.05508,进而使用BP神经网络模型反演相关系数分别提高了2%、6%.表明GPS干涉反射测量(GPS-IR)反演区域NDVI结果具有较高可靠性.该研究为获取精确位置、实时连续、高分辨率的NDVI提供了一定的理论支撑.

In view of the fact that GPS receiver is sensitive to the water content of surrounding vegetation when receiving L-band signal,the normalized difference vegetation index(NDVI)of the station is retrieved by using the change of GPS reflected signal.In this paper,the normalized microwave reflection index(NMRI)calculated from the continuous observation data of two GPS reference stations in recent five years is used to construct a univariate linear model for NDVI inversion.The correlation coefficients R of the inversion results are 0.62653 and 0.62573 respectively,and the root mean square error root mean square error(RMSE)are 0.05129 and 0.05508 respectively.The correlation coefficients of the inversion results are increased by 2%and 6%respectively by using BP neural network model,which indicates that the regional NDVI inversion results of GPS-interferometric reflectometry(GPS-IR)have high reliability.This study provides a theoretical support for obtaining accurate position,real-time continuous and high-resolution NDVI.