Soil Surface Moisture: Marmit Model and Soil Line in the Vnir Domain

A large amount of remote sensing images is now available and can be used to derive precious information about the earth. Among the information, the soil moisture is an important one. Besides microwaves, on the optics side, this has motivated research on relationship between soil reflectance and surface moisture leading to models, indices and spectral properties such as soil line. Indeed, drawing the reflectance in a near-infrared spectral band as a function of a visible spectral band reflectance, usually close to the red, for various moisture states of a soil leads to a line, called the soil line. Such a line has been observed and qualitatively explained but the theoretical physically-based explanation remains uncomplete. Thanks to the MARMIT optical model, such a line is linked to physical parameters and its slope and offset are expressed. This is a first step towards the exploitation of the soil line for surface moisture assessment.