Influence of Surface Soil Moisture on Spectral Reflectance of Bare Soil in the 0.4 – 15 Μm Domain

The purpose of this paper is to analyse the impact of surface soil moisture on spectral reflectance in the optical domain [0.4 – 15 μm]. This work is based on lab spectral reflectance measurements of many bare soils at different moisture contents. Firstly, a classification of bare soil samples is performed according to their spectral signatures: five classes are then defined. Secondly, the soil moisture content impact on spectral signatures is analysed. In the [0.4 – 15 μm] domain, measurements exhibit, for all the samples, a decreasing of the reflectance level with an increasing of moisture content. These measurements give information on absorption peaks related to soil mineral components like hydroxyl, carbonate, and quartz. Thus, analysis of our lab measurements indicates that soil moisture impact on spectral reflectance depends of studied spectral domain. These measurements may improve existing data bases, and will be used in a processing chain to estimate the soil moisture content (cases of bare soil and/or sparse vegetation) in the optical domain [0.4 – 12 μm] by using airborne hyperspectral imaging.