Detection of slush on the Greenland Ice Sheet using Moderate Resolution Imaging Spectroradiometer (MODIS) satellite imagery

Abstract: Sea Level Rise (SLR) is a growing global concern that is heavily influenced by a warming climate. Because of a potentially large added mass to the ocean through ice melt, the Greenland Ice Sheet (GrIS) plays an important role in the contribution to SLR. The presence of slush on Greenland is the result of melting processes and it can work as an indicator of surface mass balance (SMB) patterns on the ice sheet. This paper presents a detection of slush on the GrIS and the spatiotemporal evolution of slush during the study period 2000-2019. An upper limit of slush, known as the slush-line is also presented. A method is used which looks at spatial variability of albedo to detect slush on Moderate Resolution Imaging Spectroradiometer (MODIS) satellite imagery. Classification of daily satellite imagery during the study period showed a presence of slush mainly during the melting season mid-May to September each year. During the study period, slush-extents and the elevation of the slush-line were fluctuating over the years. An exceptionally large presence of slush was detected during the summer of 2012. Greater areas of slush were found on the western areas of the ice sheet; particularly large areas of slush were detected in the southwest. Slush-extent and the elevation of the slush-line showed a generally positive correlation, where an increased slush-extent results in a higher slush-line elevation. This relationship was particularly strong in the western and southern areas, while a weaker relationship was found in the eastern and northern parts of the ice sheet. This pattern is potentially related to variations in complexity of the physical environment. General developments of slush-extents over the study period show an agreement with previous studies on mass balance and particularly agree with measured cumulative melt-day extents for each year.