Wheat Microwave Scattering Characteristics

The wheat crop occupy an important position in food crops of China, the output of wheat only less than the output of rice , is the second. Production and consumption in our country are about 15%- 20% of total wheat in the world, Therefore, wheat of our country are pivotal status in the domestic market or in the world markets. Dynamic monitoring and prediction, for the wheat growing,planting area and the output, are important for people`s lives. Microwave remote sensing has some outstanding features, such as all time, all weather, penetrability, abundant information and so on, which can perfectly complete the dynamic monitoring for the wheat. This paper is based on a broad prospect of application of microwave remote sensing, to research and analysis the microwave scattering characteristics of wheat.This paper introduced the most widely used theory of vector radiation transmission: VRT is reseach intensity of the electromagnetic radiation changes after multiple scattering,absorption,propagation in uneven random medium. It is very important and meaningful in the research interaction between wave and material subject and field. Now the IEM model and the MIMICS model widly used are built based on this theory. Considered the canopy and surface two respects of wheat, this paper established double scattering model to research the factors affecting wheat growth.Using L,S,C and X land-based microwave Scatterometer to measure scattering backscattering of wheat, analyzed the variation of backscattering coefficient with the parameters change of incidence angle, polarization and earth surface, all of the study can directly supply theoretical basis to monitor wheat growing. The paper compared the simulation curve of waterclouds model and double scattering model with mesured data, the two model agreed well and had good application foreground.By inversion mesured data, to get related parameters is practical value of microwave remote sensing, which is this paper research emphasis. using polarization difference to establish inversion model, based on this model to inverse the biomass, LAI and soil moisture, total error is less than 15%.The inversion of biomass considered two period: biomass in pre-and-post heading period,and used backscattering coefficients of two angle range to inverse biomass, the result is high precision; Using the relation between PDR and LAI established inversion model,and considered the data in HH, VV polarization, the inversion had better effect; at the same time, the inversion of soil moisture used the concept of vegetation coverage, then combined with mesured LAI to inverse soil moisture,its inversion was high precision and strong practicality.