Spatial and temporal patterns in Arctic river ice breakup revealed by automated ice detection from MODIS imagery

• Main Authors: Cooley, S.W., Pavelsky, T.M.
• Other Authors: College of Arts and Sciences, Department of Geological Sciences
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier Inc. 2016
• Subjects: Arctic hydrology; MODIS; River ice breakup; Climate change; Arctic; Mackenzie Delta; Yenisey; Siberia
• Online Access: https://doi.org/10.17615/18pz-n706; https://cdr.lib.unc.edu/downloads/c821gv677?file=thumbnail; https://cdr.lib.unc.edu/downloads/c821gv677

The annual spring breakup of river ice has important consequences for northern ecosystems and significant economic implications for Arctic industry and transportation. River ice breakup research is restricted by the sparse distribution of hydrological stations in the Arctic, where limited available data suggests a trend towards earlier ice breakup. The specific climatic mechanisms driving this trend, however, are complex and can vary both regionally and within river systems. Consequently, understanding the response of river ice processes to a warming Arctic requires simultaneous examination of spatial and temporal patterns in breakup timing. In this paper, we describe an automated algorithm for river ice breakup detection using MODIS satellite imagery that enables identification of spatial and temporal breakup patterns at large scales. We examine breakup timing on the Mackenzie, Lena, Ob' and Yenisey rivers for the period 2000-2014. By dividing the rivers into 10 km segments and classifying each river pixel in each segment as snow/ice, mixed ice/water or open water based on MODIS reflectance, we determine breakup dates with a mean uncertainty of ±. 1.3 days. All statistically significant temporal trends are negative, indicating an overall shift towards earlier breakup. Considerable variability in the statistical significance and magnitude of trends along each river suggests that different climatic and physiographic drivers are impacting spatial patterns in breakup. Trends detected on the lower Mackenzie corroborate recent studies indicating weakening ice resistance and earlier breakup timing near the Mackenzie Delta. In Siberia, the increased magnitude of trends upstream and strong correlation between breakup initiation and whole-river breakup patterns suggest that earlier onset of upstream discharge may play the dominant role in determining breakup timing. Exploratory analysis demonstrates that MODIS imagery may also be used to differentiate thermal and mechanical breakup events.