Spatial-temporal variation of river ice coverage in the Yenisei river from 2002 to 2021

Abstract

River ice is an essential component of the terrestrial cryosphere, which is sensitive to global and regional climate change. The Yenisei River provides the largest river inflow to the Arctic Ocean, heavily affected by the cold climate. Data on the ice cover in the Arctic great rivers are insufficient due to the absence of a river ice database with high spatiotemporal resolution. In this study, the daily river ice coverage (RIC, defined as the fraction of river ice pixels to river pixels in a grid cell) in the Yenisei River was estimated from 2002 to 2021 in a 12.5 × 12.5 km grid, by utilizing a cloud removal method for Moderate Resolution Imaging Spectroradiometer (MODIS) data. Based on Landsat imagery reference, the RIC correlations (Pearson’s R) were 0.77, 0.84, and 0.97 for three separate validation regions. Over the past 20 years, 82.8 % of the grid cells experienced a decreasing ice cover, with 21.9 % significant at the 0.05 level. The mean winter air temperature was the key predictor (R2 = 0.48, P < 0.01), better than the accumulated negative air temperature (R2 = 0.42, P < 0.01). The spatial distribution of winter RIC exhibited a latitudinal gradient (R2 = 0.64, P < 0.01). River ice responded to temperature variation in a non-linear way, depending on latitude, with high sensitivity in the southern part of the watershed. In Lake Baikal in the river basin, the distribution of ice cover was also affected by stream inflows. The results provide a comprehensive insight into the spatial–temporal variations of the Yenisei River and explore the key factor of changes in river ice, enhancing our ability to understand the response of Arctic great rivers to climate change.