Methane emissions monitoring of rice fields using RADARSAT-2 data

A monitoring method of methane emission from rice paddies is developed by using quad-polarization radar datasets of ground-based scatterometer and space-borne RADARSAT-2. The backscattering coefficients in eight different rice growth periods are measured by using a ground-based scatterometer system, and the rice biomass, leaf-area index (LAI), water depth and CH₄ flux are collected by randomly sampling. Meanwhile, four scenes of RADARSAT-2 quad-polarization synthetic aperture radar (SAR) images covering the same study area are acquired. An experience rice parameter inversion model and a methane emissions model are established according to the measured data. The Models are applied to RADARSAT-2 image after pretreatment and classification to retrieve the rice biomass and the CH₄ flux at four dates, and come to the total methane emission, eventually. The methane emission per hectare is about 418.88 kg; it shows that methane emissions remain at a low level in the Chengdu Plain.