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微波具有穿透性,相对于可见光与红外探测器而言,微波探测器不仅能反映叶片层植被信息,还能反映较深层木质生物信息。笔者利用6.6 GHz与18.7 GHz被动微波辐射计对夏季玉米进行了不同角度(0°~60°每5°一个间隔)、不同极化(V与H极化)及不同方位(顺垄、垂直垄、垄向45°)的微波辐射特性观测试验。试验中玉米从幼苗到抽穗共分8期进行了测量,每期都利用LAI-3000实地获得了LAI数据,以此代表植被的生长状态。研究结果表明,随着观测角度和LAI的增大,V和H极化的亮温都有明显变化;微波植被指数随观测角度和LAI的变化都有明显规律;测量方位对玉米的微波辐射特性有明显的影响;土壤对植被的微波辐射影响随植被的长高而减弱。
Microwave penetration, relative to the visible and infrared detectors, microwave detectors not only reflect the leaf layer vegetation information, but also reflect the deeper wood biological information. The author uses 6.6 GHz and 18.7 GHz passive microwave radiometers to study summer maize at different angles (0 ° ~ 60 ° per 5 ° interval), different polarizations (V and H polarizations) and different azimuths , Ridge 45 °) of the microwave radiation characteristics of the test. During the experiment, the maize plants were divided into 8 phases and the seedlings were sampled. LAI data was obtained by using LAI-3000 in each period to represent the growth state of vegetation. The results show that with the increase of observation angle and LAI, the bright temperature of V and H polarization changes obviously. The change of microwave vegetation index with observation angle and LAI has obvious rules. The measurement azimuth has significant effect on the microwave radiation characteristics The influence of soil on microwave radiation of vegetation is weakened with the growth of vegetation.