Experimental Study On Microwave Radiation Features And LAI Invert Of Corn In Different Growth Season

The passive microwave sensor can provide significant information compared with optical and infrared sensors due to its penetrating property. It plays an important role in the detection of growth vigour of corps.Previous passive microwave detection experiments contributed greatly to the development of microwave remote sensing. However, those observations concentrated mainly on the observation of corps in one growth season; consecutive detection is less. Moreover, the effect of measurement direction on microwave brightness temperature was less considered. Facing for such weakness, the passive microwave detection experiments were conducted to invert Leaf Area Index (LAI) of corn in Huailai county of Hebei province of China from August to September in2010. Two passive microwave radiometers, frequency respectively at6.7GHz and18.7GHz were used to measure the brightness temperature variation of corn both horizontal and vertical polarizations in different growth stage. The measurement angle varied from0°to60°at interval of5°and the measurement direction varied respectively in parallel, vertical to the row and cross45°with the row. The detection period included eight stages of corn growth. In addition, LAI-3000was used to obtain the corn’s LAI of every growth stage.From the experiment we found that:①With the increase of measurement angle and LAI, both polarization’s brightness temperatures change obviously;②There are visible rules for microwave vegetation indices with the increase of measurement angle and LAI;③When measurement direction is parallel to the row, the action of scattering is weaker as the row’s periodic function; Moreover, with the growth of corn, the effect of soil gets smaller.④LAI could be inverted by Normalized Microwave Polarization Difference Index (MPDI) of6.6GHz and60°measurement angle.The results of this study have offer new experimental basis for passive microwave remote sensing detect on the growth vigour of vegetation, and a microwave-based exponential molder for the invert of corn’s LAI and its parameters are presented, have actual significances on remote sensing detection and early-warning of land use, mining area environment and corp, have develop the context of study and technology of detection.