Author(s): Jiahui Qiu; Kari Luojus; Harri Kaartinen; Yubao Qiu; Jari Silander; Epari Ritesh Patro; Bjorn Klove; Ali Torabi Haghighi
Linked Author(s): Björn Klöve
Keywords: MODIS; River ice; Arctic region; Google Earth Engine; Climate change
Abstract: River ice profoundly influences Arctic hydrology, navigation, and ecosystem processes, yet consistent daily observations at the pan-Arctic scale remain limited. This study presents a multi-decadal dataset of daily river ice concentration (RIC) and annual ice phenology (freeze-up, breakup, and duration) for the six largest Arctic rivers—Yukon, Mackenzie, Ob, Yenisey, Lena, and Kolyma—during 2001–2024. Using over 590,000 MODIS Terra/Aqua scenes, we developed a scalable workflow on Google Earth Engine that integrates dual-satellite daily synthesis, temporal-window cloud reclassification, and high-latitude dark-period correction. Validation with high-resolution Harmonized Landsat and Sentinel-2 (HLS) data yields a mean RIC accuracy of 0.83 across basins. MODIS-derived phenological metrics show strong agreement with in situ observations (mean absolute errors: 10.8 days for freeze-up and 11.4 days for breakup) and Landsat-based reference datasets (10.5 and 16.0 days, respectively). RIC is strongly correlated with surface air temperature (mean r = −0.91) and increases with latitude. Spatially coherent trend analyses indicate delayed freeze-up in over 66 % of river segments, earlier breakup in more than 65 %, and shortened ice seasons in over 65 %. On average, freeze-up is delayed by 9.0 days, breakup occurs 7.8 days earlier, and ice duration shortens by 14.1 days.
Year: 2026