Observations of an Emerging Ice-Free Zone in the Sea of Okhotsk during the Spring Sea-Ice Melting Period amid the 2023 Global SST Warming

Starting from May 2023, a global anomaly event led to the highest recorded sea surface temperature (SST) in history, underscoring the urgency of understanding how warming oceans impact polar and subpolar regions. Against this backdrop, our study focuses on the Sea of Okhotsk, where data from the U.S. National Snow and Ice Data Center and sea surface height measurements revealed an unprecedented, ice-free zone—measuring 50 to 80 kilometers in radius—near the Gulf of Patience (たらいかわん), east of Sakhalin Island, during Feb. – Mar. 2023. This phenomenon stands in stark contrast to observations in previous years and appears closely linked to sea surface height anomalies (SSHA). The role of such localized oceanic features, including eddies, in shaping late-spring sea ice melting patterns is of interest.

During the SOYA cruise in February 2023, National Central University (Taiwan) and Hokkaido University deployed eleven Taiwan-made drifting wave buoys. These buoys captured high-resolution data on waves, ocean currents, and sea temperatures, revealing robust mesoscale ocean eddy activity within the region. This study integrates buoy-based observations, satellite remote sensing, and numerical model outputs to explore the dynamic relationship between mesoscale eddies and the rapid formation of the ice-free zone. It is the aim to investigate how eddies influence springtime sea ice melting and distribution in the Okhotsk Sea. The preliminary findings may have implications for climate modeling, marine ecosystems, and regional socioeconomic activities, and will be shown in detail in the poster.