Imaging Spectroscopy in Hydrology and Agriculture - Determination of Model Parameters

Abstract

In the framework of hydrologic research a better knowledge of the characterisation of the land surface is essential for improved modelling of the global hydrological cycle. The upcoming Imaging Spectroscopy space missions will provide a more exact view of the land surface. To prepare this, the potential of airborne Imaging Spectroscopy data of the GER-IS-scanner and the CASI-sensor for the assessment of agricultural and hydrological parameters is analysed. The data of the aircraft campaigns are combined with a set of agricultural ground truth and field spectrometry to give an insight into methods of integrated data analysis.

After atmospheric correction and calibration, the resulting reflectance values of the wavelength region, which contains the most characteristic spectral features of vegetation, the red edge, are parameterised. Two methods (inverted Gaussian fit, second derivative) are used and their advantages and limitations are demonstrated. A strong correlation between the vegetation height of corn and the inflection wavelength of the red edge is found. This correlation exists independent of sensors, different methods for extracting the inflection wavelength, different times and different soil backgrounds. The possibility to use data of the future MERIS-sensor for quantitative red edge analysis is tested.