L-Band Radar Experiment and Modeling of a Corn Canopy Over a Full Growing Season

Modeling L-band backscatter from a corn canopy continues to be a challenge due to the complex dynamics in both plant phenology and the underlying soil. An experiment has been conducted to better understand the relationship between L-band backscatter and canopy parameters such as soil moisture, vegetation water content, dew, and periodic rows. The experiment consists of field measurements that take into account plant phenology and are concurrent with L-band backscatter returns from a corn canopy over a full growing season. The field measurements of the corn plants’ constituents highlight modeling complexities, such as an inhomogeneity in the dielectric constant of the stalk and cobs. A simple method to replace the stalk and cob with a homogeneous dielectric constant is validated. Using the field measurements in a scattering model developed at George Washington University (GW), both coherent and incoherent backscatter are computed. The results show coherent effects contributing to enhanced backscatter by up to 2.7 dB for both HH-pol and VV-pol. The coherent model and the detailed measurements, especially, the dielectric constant of the stalks, resulted in good agreement with the measurements. These measurements have an average root mean square difference (RMSD) with the results from the coherent model of around 1 dB for both HH-pol and VV-pol over the entire growing season. The incoherent mode does not perform as well.

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