FraRI: an algorithm to account for the discontinuity at 60° N in MODIS temperature products
Abstract:The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra and Aqua satellites conducts continuous monitoring of the Earth's land surface and oceans. Recently, a sharp discontinuity (averaging 1.9°C) has been noticed at 60° N in both MODIS daytime and night-time land surface temperature (LST) products. This linear artefact arises because the CO2 high cloud test in the operational code for the generation of the MODIS cloud mask product is used only in the non-polar region (between 60° N and 60° S). The resulting discontinuity clearly has negative implications for any statistical applications of these temperature data. In this technical note we present a new algorithm, which minimizes this discontinuity. The method uses edge detection and elimination based on a mixture of Sobel and non-linear Laplacian filters (edge detection and quantification), cubic splines (edge modelling), and a controllable power function for image restoration. The implementation of this algorithm is demonstrated on an image of average minimum night-time LST between 2001 and 2008.
Document Type: Research Article
Affiliations: 1: Spatial Ecology and Epidemiology Group, Zoology Department,University of Oxford, Oxford, UK 2: Environmental Research Group Oxford (ERGO), Zoology Department,University of Oxford, Oxford, UK 3: Earth Research Institute,University of California, Santa Barbara,CA, USA
Publication date: 2013-02-20