Tropical Rain Forest-based Space-borne Polarimetric Sar Calibration Program

Polarimetric synthetic aperture radar (POLSAR) is an important microwave remote sensor. POLSAR data have been applied extensively in the world wide. With the researches and applications moving forward, calibration of POLSAR developed rapidly. Especially in recent years, based on the tropical rainforest, POLSAR calibration has been emphasized. This thesis is aimed to do some research working on POLSAR calibration by using the tropical rainforest, by referencing the comprehensive results of the major study on SAR calibration world wide. Specifically include the followings:Radiometric calibration1. Antenna Pattern in-orbit testing program. The existent calibration approaches are introduced, and the influence on the calibration performance of different calibration bodies is analyzed thoroughly. The tropical rain forest is chosen as the calibration field after careful considerations. In this thesis the principles and methods on antenna Pattern in-orbit testing are described, the flow chart of the test procedure is illustrated and the test accuracies are evaluated.2. System noise and signal-to-noise ratio measurement program. There are many large water bodies in the rain forest regions, whose backscatter coefficient is small enough to detect the thermal noise level of the system.3. Roll angle error measurement program. Provided that the backscatter coefficient of the rain forest is known and independent of the incident angle, the roll angle error is retrieved by the calibration results.4. Image uniformity test. The image uniformity is validated thanks to the constant scattering feature of the rain forest.Polarimetric calibration. The principles of the polarimetric calibration are interpreted and two different ways in solving the calibration equation are presented: the method based on three-component scattering model and maximal likelihood estimator (MLE). After thoroughly analysis, the latter method is chosen.Finally thesis analyzes the feasibility of the program,through discussions of the application examples on SAR calibration by using tropical rainforest in the world wide.