A disaggregation approach for estimating high spatial resolution broadband emissivity for bare soils from Landsat surface reflectance

High spatial resolution land surface broadband emissivity (BBE) is not only useful for surface energy balance studies at local scales, but also can bridge the gap between existing coarser resolution BBE products and point-based field measurements. This study proposes a disaggregation approach that utilizes the established BBE-reflectance relationship for estimating high spatial resolution BBE for bare soils from Landsat surface reflectance data. The disaggregated BBE is compared to the BBE calculated from spatial-temporal matched Advanced Spaceborne Thermal Emission and Reflectance Radiometer emissivity product. Comparison results show that better agreement is achieved over relative homogeneous areas, but deteriorated over heterogeneous and cloud-contaminated areas. In addition, field-measured emissivity data over large homogeneous desert were also used to validate the disaggregated BBE, and the bias is 0.005. The comparison and validation results indicated that the disaggregation approach can obtain high spatial resolution BBE with better accuracy for homogeneous area.