Modeling moulin distribution on Sermeq Avannarleq glacier using ASTER and WorldView imagery and fuzzy set theory

Abstract

A fuzzy set overlay model is used to analyze the distribution of moulins (vertical meltwater conduits) on Sermeq Avannarleq (“Dead Glacier”) in West Greenland in 1985 and 2008–09. Input data is derived from a historical topographic map based on airborne visible imagery and more recent WorldView-1 panchromatic imagery, as well as an Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) digital elevation model (DEM). A non-parametric best-fit model approach using a Monte Carlo simulation is used to derive the membership functions for moulin location based on three independent variables – elevation, slope and aspect – and to test for the robustness of the model. We determine that there is a topographic setting independent of time that favors the development of moulins in this region. Using the membership functions, and an optimal alpha cut derived for 1985, we could correctly predict the locations of ~ 88% of the moulins in 2008–09. The model accounts for increased surface melt in 2008–09 in comparison to 1985. Our results demonstrate the potential of a fuzzy set based approach to improve models of ice sheet hydrology in Western Greenland, by providing more reliable spatial distributions of entry points of meltwater into the ice based on remotely sensed datasets of the ice surface, which are readily available.