Inversion of Vegetation Biochemicals by Remote Sensing
植被生化组分的遥感反演方法研究

The knowledge of foliar biochemical concentration provides us a deep understanding of many esosystem functions, such as photosynthesis, nutrient cycling, and so on. Generally speaking, two ways of biochemical concentration estimation by remote sensing, namely statistical regression and physical model inversion, have been studied in parallel. There are many limitations in statistical regression method. So, direct inversion of physical model is desired. From the view of inverting physical models to retrieve biochemical concentration, inversion methods were analyzed at leaf and canopy level respectively. At leaf level, using laboratory measured spectra and PROSPECT model, water and chlorophyll concentration were inverted quite accurately. Through comparing true spectra with reconstructed spectra using true inputs, results were got as that accurate inversion of some parametes are based on the model which should describe the effect of this parameter accurately. At simulated canopy level, preliminary inversion of biochemical content directly from canopy spectra showed poor accuracy especially for chlorophyll. Based on the idea of multi stage inversion, following inversion was decomposed into 2 parts: first from canopy spectra to leaf spectra, then from leaf spectra to biochemical content. By this step by step inversion strategy, biochemical concentration was inverted accurately ultimately.It should be noted that in this paper the canopy spectra was simulated by model, further testifying with real spectra is needed which we will take into consideation in near future. Also other inversion algorithms than iterative optimization will be tested.