The leaf area index(LAI)is an important parameter to quantitatively describe the structure of vegetation and crops.Uncertainty in the relationship between the LAI and polarimetric parameters is the key problem for LAI estimation from polarimetric synthetic aperture radar(POLSAR)data.However,the existing POLSAR data have difficulties meeting the demand of the aforementioned research.This paper analyses the correlations between the LAI and the polarimetric parameters derived from Cloude and Freeman decompositions using simulated POLSAR data based on a coherent scattering model for maize and wheat.The results show:(1)The POLSAR data at C-band with a large incidence angle(40 degrees)are very suitable for finding the LAI for maize and wheat.(2)For maize there is a strong correlation between the scattering type angle and the LAI at C-band with a large incidence angle,and the coherency entropy,anisotropy,and the power of the double-bounce scattering power component also have significant correlations with the LAI.(3)For wheat at Cband with a high incidence angle,although the correlation coefficient is low,there is still a correlation between the entropy,anisotropy and LAI.Besides,the volume scattering is suitable for extracting the LAI for wheat at X-band.
