Using normalized multi-band drought index for high spatial resolution soil moisture mapping

Soil moisture is an important factor as it has tremendous effects on agriculture production, the environment and climate. For the soil moisture estimation, traditionally, direct soil sampling has been done, but this is labor intensive, very slow, and may be very expensive, hence for large regions Remote Sensing technology is a feasible alternative. The Advanced Microwave Scanning Radiometer (AMSR-E) provides global soil moisture product which has a spatial resolution of 25km but the spatial resolution is not good enough to satisfy the demand for agricultural planning or drought monitoring hence it is necessary to find a method to retrieve Soil Moisture (SM) with higher spatial resolution. In this study, AMSR-E soil moisture in combination with Normalized Multi-Band Drought Index (NMDI) derived from Moderate Resolution Imaging Spectroradiometer (MODIS) satellite imagery is used to generate higher spatial resolution SM in the Central American region for the 2010 dry season. The combination of the advantages of both, high spatial resolution provided by NMDI and physical units of AMSR-E soil moisture products are used to derive a model which can estimate the SM with higher spatial resolution. The model for SM estimation is validated using checkpoints and the validation results reveal satisfactory results. The estimations can serve as a tool for drought monitoring, prevention and mitigation actions especially in regions, such as Pacific region, which are highly vulnerable to drought.