Estimation of soil moisture from space-acquired remote sensing data

Soil moisture is a critical variable in prediction models for the fields of agriculture and hydrology. A precise measurement of soil moisture, over large areas and repetitively, can lead to accurate estimates of crop yields, water runoff, and soil erosion.

Space-acquired remote sensing data, because of its synoptic view and repetitive coverage, has the potential for being used in estimation of soil moisture conditions over large areas. The interaction of electromagnetic radiation with soils forms the basis of soil moisture measurement from remote sensing data. Due to extreme thermal and dielectric properties of water, the corresponding properties in the soil are dependent on the amount of water present in the soil. The change in soils' thermal and dielectric properties causes reflection and emission of radiation from the soil surface to be modified.

Remote sensing techniques for soil moisture estimation based on reflected solar radiation, emitted thermal infrared radiation (IR), and microwave radiation are presented. The thermal IR techniques of soil moisture measurement seem to be most promising presently. These techniques are based on the principle that a modulating effect of soil water on the soil surface temperature is due to latent heat and thermal inertia. The construction of thermal inertia images is achieved by remote sensing inputs to a thermal inertia model.

Based on thermal inertia modeling, an experiment for testing the utility of space-acquired thermal IR remote sensing data for soil moisture estimation is proposed.