Study on representative area of leaf area index retrieval

In the field measurement of leaf area index (LAI) which is necessary as a validation of LAI retrieval from remote sensing image, measuring the whole pixel-sized sample plot has always been a difficulty. In this research, the concept of Representative Area,which is smaller than the pixel size yet large enough for measuring LAI of the pixel,is proposed as a solution and is estimated in an experiment. Focused on intercrops, the measured LAI of sample plots using LAI-2000, each contains several gradually increasing scale of area, and the retrieved LAI of the corresponding pixels from 30-resolution TM image are obtained. By analyzing the correlation coefficient (CC) in term of every scale of area,between the group of measured LAI values and the group of retrieved LAI values, an area-CC curve is formed. The area corresponding to the very point where this increasing curve begins to turn stable is the estimated representative area.