Integration of space-borne and air-borne data in monitoring river ice processes in the Slave River, Canada

River ice plays an important role in the physical, biological, and human systems in northern regions. Due to the large extent and poor accessibility of many river systems, remote sensing techniques are a potential tool for collecting information and analyzing characteristics of river ice covers. Optical data with high temporal resolution (e.g. MODIS products) are suitable for monitoring river ice phenology and mapping river ice cover extent, while radar data (e.g. RADARSAT-2 imagery) offer an optimal approach to characterizing river ice thickness, ice types and seasonal changes of ice-cover characteristics. An integrated automated approach, utilizing remotely sensed data from both active and passive sensors, was developed and applied to characterize river ice processes along the Slave River, Northwest Territories, Canada. The results show that the analysis of MODIS band 2 (841-876 nm) time series can detect the date of river ice freeze onset (FO) and water clear of ice (WCI) with a deviation of up to 12 days and 3 days, respectively. The rate of river ice breakup is much faster than the rate of river freezeup. The profiles of MODIS band 2 reflectance data along the river, however, showed insignificant differences between different breakup stages and ice types, making it challenging to map breakup ice types. In this case, RADARSAT-2 imagery can be used successfully to characterize and map four classes of water and ice covers during the breakup period, including intact ice, smooth rubble ice, rough rubble ice and open water. In association with hydrometeorological parameters, the thermal deterioration of the ice cover during breakup appears to be the primary breakup event in the Slave River. The results obtained from the analysis of MODIS and RADARSAT-2 data were compared with ground measurements of weather, flow and ice conditions (2000-2015), time-lapse photos and aerial surveys (2013-2015) along the Slave River, and show strong agreement. Crown Copyright (C) 2016 Published by Elsevier Inc. All rights reserved.